رامین عبدلی

One of the goals of new programs for silkworm breeding is to investigate the ability to withstand environmental fluctuations. Silkworms are cold-blooded organisms, meaning that their body temperature and metabolic processes are affected by the temperature of the environment. Silkworms are sensitive to temperature changes, and exposure to cold temperatures can affect their growth, development, and overall health. So far, no special attention has been paid to improving compatibility traits in Iranian silkworms. The requirement of this goal is to improve the traits related to resistance to stresses and adaptation to new conditions. Achieving this regard requires expanding the country's silkworm gene bank, especially in the field of commercial lines. New genetic resources should also be made available while identifying the genetic capabilities of the existing lines. In the meantime, producing eggs that are resistant to cold stress is one of the proposed solutions to deal with this stress. For this purpose, it is necessary to determine the level of resistance or susceptibility to cold stress in commercial lines used in the production of commercial eggs, and the desired lines should be rated from this aspect. With this rating, recommendations can be made to create crosses between the mentioned lines aiming at producing commercial eggs resistant or sensitive to cold stress and distributing each batch of these eggs in different geographical areas with different climates. In the present study, the performance of commercial lines of Iranian silkworms including 31, 32, 103, 104, 151, 153, and 154, under cold stress was investigated in control and challenge treatments.

After the steps of preparation for breeding, silkworm eggs were kept in a hatching room under standard temperature and humidity conditions for 12 days. The standard conditions for breeding were temperature (25 ± 2 °C), relative humidity (75 ± 5%), and photoperiod (16 hours light/ 8 hours dark). Mulberry leaves of modified varieties were used to feed the larvae. To induce cold stress, 300 larvae on the third day of the fifth instar (in the form of three replicates of 100 larvae) were incubated at 0 °C for 12 hours and then returned to the standard rearing conditions at 25 °C. The production traits the characteristics of cocoon weight, cocoon shell weight, cocoon shell percentage, number of cocoons per liter, cocoon weight per liter, the average weight of a cocoon, the average weight of the best cocoon, the average weight of a middle cocoon, the  average weight of a weak cocoon, and the average weight of a double cocoon, as well as some traits related to longevity, including the percentage of live larvae, the percentage of dead larvae, the percentage of pupal losses, and the percentage of produced butterflies, were investigated in each cold stress and control treatments. For statistical analysis, the generalized linear model (GLM) procedure was used in SAS software, and means were compared with Tukey's statistical test at a significant level of 0.05.

In general, the highest and lowest values of traits were not the same among the genotypes and under applied stress conditions, but some genotypes showed higher performance for a larger number of traits. Among the studied traits, those related to cocoon weight, cocoon shell weight, and cocoon shell percentage are the most important traits for breeding purposes, which have high economic values and are used to improve cocoon performance. Meanwhile, the live and dead larvae percentage traits, along with death pupae percentage and productive moth percentage, are important indicators related to viability, which showed significant differences between the studied lines. The results of mean comparisons showed that the larvae of the control group generally had better performance in all the examined traits than the larvae under cold stress, with a significant difference (P < 0.001). However, two lines 153 and 154 from the cold stress group had higher performance in many production and longevity traits than the other lines under cold stress and even some lines of the control group.

The temperature of the breeding environment is one of the factors that, in the case of fluctuation, leads to the deviation of breeding conditions from the optimal state and damage. In general, cold stress and low temperatures have different effects on insects, considering the intensity and duration of the insect's exposure. In addition, the stage of life, the evolution degree of adaptation mechanisms, and adaptation to the environment greatly affect the insect's response to cold stress. The results of the present research show that the performance of commercial lines of Iranian silkworms is affected under cold stress conditions, and lines 153 and 154 have higher resistance than the other lines. Hence, they can be prioritized in the production of commercial hybrids in terms of resistance to cold stress and production and survival records. Further studies are suggested to measure the molecular and biochemical characteristics of some proteins related to temperature stress in different treatments.

Considering the importance of comparing the silkworm performances of Iranian and imported commercial hybrids from China production traits, viability index and cocoon dimensions index were investigated in eight Iranian (31×32, 32×31, 103×104, 104×103, 151×154, 154×151, 153×154 and 154×153), and nine imported Chinese commercial hybrids (Suju×Minghu (S×M), Minghu×Suju (M×S), Baiyue×Qiufeng (B×Q), Qiufeng×Baiyue (Q×B), BaiyueB×QiufengA (BB×QA), QiufengA×BaiyueB (QA×BB), 781×7532, Lianggang No2 and Guican No 5) in the present study.
After eggs hatched and according to the standard protocols, the studied hybrids were reared under the same conditions at Iran Silk Research Center (ISRC). Statistical analyses were done in three replications of 200 larvae (totally 600 records per each hybrid) based on completely randomized design. For comparing the means, Tukey's statistical test was used at a significance level of P<0.05. The GLM procedure was used in SAS software version 9.4. Data generated in respect of the studied traits were subjected for further analysis by a multiple trait evaluation index using the following formula: evaluation index (E.I.)= (A-B/C×10) + 50, where A is value of a particular breed for particular trait, B is mean value for a particular trait of all the hybrids, C is standard deviation of a particular trait for all the hybrids, 10 is standard unit and 50 is fixed value. Minimum / average Evaluation Index (E.I) value fixed for selection of a hybrid is >50. Based on the evaluation index (E.I) consisted of production traits and viability, best hybrids were identified.
The result of the research showed the close competition between Iranian and Chinese silkworm hybrids. In the situation that the performance of Iranian 32×31 and 31×32 hybrids for traits related to weight, shell weight and shell percentage of best cocoons was higher than the other hybrids but based on a composite index that was used in this research, 151×154, 154×151, 153×154 and 154×153 hybrids showed superiority. Based on this index, M×S and S×M as well as BB×QA and QA×BB had a higher average than the other hybrids. This result is based on the average of two-way crosses for the hybrids that both pairs were used in the experiment.
Generally, the results of mean comparisons and evaluation index showed that Iranian hybrids had better performance in all traits related to produce cocoons than the Chinese hybrids. Although, Chinese hybrids were significantly different from the Iranian for pupa viability percentage trait as Lianggang No2 hybrid showed the highest value.

Phylogeny as a science that study the evolutionary relationships between species and populations of organisms, as well as their evolutionary history, diversity and patterns of population changes, by integrating genomic data, has become a strong approach in the study of the systematic of species named phylogenomics. The aim of the present study were divergence study an percent genetic similarity along with phylogenetic analysis of the seven existence species of the Equidae family based on mitochondrial genome sequences.

In order to investigate genetic divergence and similarity, the most up-to-date complete sequences of the mitochondrial genome along with the separate sequences of 13 protein coding genes per each genome from seven main Equidae species including E. africanus, E. ferus, E. grevyi, E. hemionus, E. kiang, E. quagga and E. zebra were extracted from NCBI database site and compared to each other.

The results of sequence distance analysis based on the complete mitochondrial genome showed that the highest genetic similarity (99.9%) was observed between Asian wild donkey (E. hemionus) and Tibetan donkey (E. kiang) and the lowest genetic similarity (92.3%) was observed between Asian wild donkey (E. hemionus) and Przewalski's horse (E. przewalskii). In terms of phylogenetic analysis, E. przewalskii species was placed in a separate cluster, and E. africanus, E. grevyi, E. hemionus, E. kiang, E. quagga and E. zebra were placed in a another cluster. The analysis of the nucleotide sequences of 13 protein encoding genes per each genome showed that in all these genes E.kiang and E.hemionus species had the most genetic similarity to each other and also the least genetic similarity was observed between E.przewalskii and E.asinus species. In terms of phylogenetic analysis, E.przewalskii species had the highest distance from other species and was not included in the main cluster, which results were similar to the analysis of complete mitochondrial genome sequences. Also, the results of the analysis for the amino acid sequences of 13 protein-coding genes showed that unlike the nucleotide sequences, the highest and least genetic similarity may be different in the species. Although, E. kiang and E. hemionus species had the most genetic similarities, and the lowest genetic similarity of the species was related to E. przewalskii and E. zebra species, and in terms of phylogenetic analysis, E. przewalskii had the highest distance from other species and was not included in the main cluster.

This research showed that the examination of mitochondrial genomes and sequences of Equidae species can help to determine the evolution and biological processes in the past of these species, as well as to determine the distribution and relationship between different species of the Equus genus and the possibility of correct clustering of the species exists based on the mitochondrial genome.

So far, many researches have been conducted to compare the productivity of different silkworm hybrids in Iran, which were just based on the evaluation of cocoon traits, eg. cocoon weight, cocoon shell weight, cocoon shell percentage, pupation rate, etc. In the present study, with the aim of obtaining information on the quality characteristics of silk thread in Iranian silkworm hybrids, 80 Iranian silkworm hybrids were examined for silk thread characteristics. 72 of the new silkworm hybrids in addition to 8 current commercial hybrids were evaluated for the six silk thread characteristics including yarn size (YS), yarn length (YL), yarn tensile strength (YTS), elongation percentage (EP), yarn weight (YW) and raw silk percentage (RSP) based on dry weight. 200 good cocoons from each hybrid were sampled at the Iran Silk Research Center and sent to the Fiber Physics Laboratory of the University of Guilan. After re-evaluating the individual cocoons based on form and size of them, 3 repetitions of 21 cocoons (based on the capacity of the spinning machine) were spun and dried. According to reciprocal crosses in this research, the data were analyzed using a completely randomized design (CRD) with two sources of variation (40 hybrids and two types of crosses) by the GLM procedure of SAS software version 4.9. Mean comparison of the studied traits based on the combined reciprocal data (40 hybrids) showed that the highest average of the FS trait (73.3 deniers) was for the hybrid IRA3×IRA10 and the lowest average (58.2 deniers) for the commercial hybrid 153 ×154. The highest YL trait(771.4 m) was for hybrid IRA5×IRA8 and the lowest (441.18 m) for the commercial hybrid IRA2×IRA3. The highest average of the YTS (3.47 g/denier) was for commercial hybrid 104×103 and the lowest average (2.9 g/denier) was for hybrid IRA2×IRA3. The highest average for the EP trait (17.6%) was reported for the commercial hybrid 154×151 and the lowest average (12.83) was related to the hybrid IRA2×IRA3. The highest average for YW (5.59 grams) belonged to the IRA5×IRA8 hybrid and the lowest average (3.34 grams) belonged to the IRA2×IRA3 hybrid. Also, for the RSP trait (the most critical trait of silk characteristics), The IRA5×IRA8 hybrid had the highest average (41.4%) and the IRA2×IRA3 hybrid had the lowest average (25.86%). IRA5×IRA8 hybrid had superior performance than all commercial hybrids. The RSP of the IRA8×IRA9 hybrid was 39.47%, which was superior to the three commercial hybrids. The hybrids that were excellent in at least three of the six characteristics were: all commercial hybrids and three new hybrids including IRA5×IRA8, IRA11×IRA12 and IRA8×IRA9. Analysis of the variance of the traits showed that the reciprocal-cross effect was not significant for the YS and YTS traits (P>0.05). Despite the close competition of new hybrids with current commercial hybrids, many characteristics of commercial hybrids were significantly higher than new hybrids. However, the new hybrids including IRA2×IRA9, IRA2×IRA11, IRA3×IRA4, and IRA4×IRA11, which have shown superiority in terms of cocoon traits, also performed favorably in terms of all yarn characteristics. However, two hybrids were among the superior hybrids in terms of cocoon production and cocoon traits, but the results of the present research showed that they are not superior in terms of yarn characteristics and raw silk yield and productivity, including IRA2×IRA3 and IRA4×IRA7. The IRA2×IRA3 hybrid has an unfavorable performance in terms of weight, strength, and raw silk percentage and cannot provide the interests of silk spinners. In the final selection of new hybrids based on the performance of both cocoons and silk thread, it is necessary to pay attention to the strength and weakness of the silk yarn obtained from the cocoons of each hybrid. But it will not be the case that hybrids with better cocoon performance are necessarily among the best in terms of all silk yarn traits or even some of them. For example, hybrids IRA2×IRA9, IRA2×IRA11, IRA3×IRA4, and IRA4×IRA11 had better cocoon performance, but they had a middle performance for yarn characteristics. In other words, if they are not among the weaker group, they can be considered. Generally, it is necessary to decide about new hybrids after rearing them in rural conditions and evaluating the produced cocoons and yarns.

Penaeidae shrimp species are the most important farmed aquatic animals from the crustacean group which have gained an important economic position in the world's aquaculture industry. In this study, complete mitochondrial genome sequences along with nucleotide and amino acid sequences of 13 PCGs per each genome from 10 important Penaeidae shrimp species were obtained from NCBI database and compared. According to the complete mitochondrial genome, the highest (88.5%) and lowest (76.4%) genetic similarity was found between Fenneropenaeus indicus and Fenneropenaeus merguiensis, and Metapenaeus ensis and Penaeus monodon, respectively. In phylogenetic analysis of the complete mitochondrial genome, two main clusters were established at the beginning of the phylogenetic tree. Metapenaeus ensis and Metapenaeus affinis were placed in one main cluster and other species in another main cluster. The results of the phylogenetic analysis of the nucleotide and amino acid sequences of the 13 PCGs showed that M. ensis and M. affinis, Litopenaeus stylirostris and Litopenaeus vannamei, and F. merguiensis and F. indicus species were grouped in different clusters, which confirms the results obtained from the comparison of the complete mitochondrial genome. Based on the results, mitochondrial genome sequences could be used for a wide range of detailed phylogenetic and genetic analyzes of different shrimp species.

Considering the production of new silkworm hybrids by prominent countries in the sericulture industry such as China and the import of these hybrids to the country in recent years, it is necessary to update these evaluations so that correct decisions can be made to choose the most suitable type of hybrid in terms of functional traits. Therefore, such comparisons are done annually and the results are sent to the Iran Sericultural Corporation- Silk Worm Research Center as an executive body for final decision. The present study aimed to investigate the performance of eight Chinese commercial silkworm hybrids, including Suju×Minghu (S×M), Minghu×Suju (M×S), Baiyue×Qiufeng (B×Q), Qiufeng×Baiyue (Q×B), BaiyueB×QiufengA (BB×QA), QiufengA×BaiyueB (QA×BB), 874×873, and 874×873. Hybrids 872×871 and 872×871 also were among the studied hybrids, but due to the decrease in the performance of cocoon-related traits compared to other hybrids that had a big difference in terms of the obtained values, they were removed and excluded from the final analysis. The desired hybrids for 14 traits including best cocoons weight produced per 26,000 larvae (BCW), total cocoons weight produced per 26,000 larvae (TCW), number of cocoons per liter (NCPL), weight of cocoons per liter (WCPL), percentage of pupa viability (PPV), mean weight of a cocoon (MWC), mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon (MWMC), mean weight of a male cocoon shell (MWMCS), mean of male cocoon shell percentage (MMCSP), mean weight of a female cocoon (MWFC), mean weight of a female cocoon shell (MWFCS), and mean of female cocoon shell percentage (MFCSP) were reared in the spring of 2022 after hatching and according to standard methods and under the same conditions in Iran Silk Research Center and their performance was recorded. Each silkworm hybrid was reared in three replications of 200 larvae (total number of observations including 600 records per hybrid for all traits) in a completely randomized design. The analysis of the obtained data was done by SAS software by using the procedure of generalized linear model (GLM), and the average performance of the traits was compared to each other using Tukey's range test at the probability level of P<0.05. The results of the analysis of variance for the studied traits showed that the effect of the hybrid type for most of the studied traits including best cocoons weight produced per 26,000 larvae (BCW), total cocoons weight produced per 26,000 larvae (TCW), number of cocoons per liter (NCPL), the weight of cocoons per liter (WCPL), mean weight of a cocoon (MWC), mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon (MWMC), mean weight of a male cocoon shell (MWMCS), mean of male cocoon shell percentage (MMCSP), mean weight of a female cocoon (MWFC), mean weight of a female cocoon shell (MWFCS) and mean of female cocoon shell percentage (MFCSP) was significant (P<0.05). In the meantime, only traits of the percentage of pupa viability (PPV) as the most important index related to survival and the mean of male cocoon shell percentage (MMCSP) were not affected by the hybrid type (P<0.05). The average performance of the hybrids showed a significant difference (P<0.05) for all the traits except for the percentage of pupa viability (PPV) and the mean of cocoon shell percentage (MCSP). The BB×QA hybrid showed a higher performance than other hybrids for six traits including the best cocoons weight produced per 26,000 larvae (BCW), the total cocoons weight produced per 26,000 larvae (TCW), the weight of cocoons per liter (WCPL), the mean weight of a cocoon (MWC), the mean weight of a male cocoon (MWMC), and the mean weight of a female cocoon (MWFC) (P<0.01). Also, the M×S hybrid showed a higher performance than other hybrids for the five traits of the mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon shell (MWMCS), mean weight of a female cocoon shell (MWFCS), and the mean of female cocoon shell percentage (MFCSP) (P<0.05). In addition, the M×S hybrid showed the lowest value compared to other hybrids for the number of cocoons per liter (NCPL), which the lower values of this trait are preferred (P<0.01).  Based on the results of the present research, the priority of importing and rearing silkworm eggs in 2023 is suggested for BB×QA and M×S hybrids. Although the performance of these two hybrids with other hybrids, except for the 874×873 and 874×873 hybrids, is not significant in most of the examined traits, they can still be considered as next-import priorities. The desired hybrids for 14 traits including: best cocoons weight produced per 26,000 larvae (BCW), total cocoons weight produced per 26,000 larvae (TCW), number of cocoons per liter (NCPL), weight of cocoons per liter (WCPL), percentage of pupa viability (PPV), mean weight of a cocoon (MWC), mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon (MWMC), mean weight of a male cocoon shell (MWMCS), mean of male cocoon shell percentage (MMCSP), mean weight of a female cocoon (MWFC), mean weight of a female cocoon shell (MWFCS) and mean of female cocoon shell percentage (MFCSP) were reared in the spring of 2022 after hatching and according to standard methods and under the same conditions in Iran Silk Research Center and their performance was recorded. Each silkworm hybrid was reared in 3 replications of 200 larvae (total number of observations including 600 records per hybrid for all traits) in a completely randomized design. The analysis of the obtained data was done by SAS software (version 9.4) by using the procedure of generalized linear models (GLM) and the average performance of the traits was compared to each other using Tukey's range test at the probability level of P<0.05. The results of the analysis of variance for the studied traits show that the effect of the hybrid type for most of the studied traits including best cocoons weight produced per 26,000 larvae (BCW), total cocoons weight produced per 26,000 larvae (TCW), number of cocoons per liter (NCPL), the weight of cocoons per liter (WCPL), mean weight of a cocoon (MWC), mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon (MWMC), mean weight of a male cocoon shell (MWMCS), mean of male cocoon shell percentage (MMCSP), mean weight of a female cocoon (MWFC), mean weight of a female cocoon shell (MWFCS) and mean of female cocoon shell percentage (MFCSP) is significant (P<0.05). In the meantime, only traits of the percentage of pupa viability (PPV) as the most important index related to survival and the mean of male cocoon shell percentage (MMCSP) were not affected by the hybrid type (P<0.05). The average performance of the hybrids showed a significant difference (P<0.05) for all the traits except for percentage of pupa viability (PPV) and the mean of cocoon shell percentage (MCSP). The hybrid BB*QA showed a higher performance than other hybrids for six traits including the best cocoons weight produced per 26,000 larvae (BCW), the total cocoons weight produced per 26,000 larvae (TCW), the weight of cocoons per liter (WCPL), the mean weight of a cocoon (MWC), the mean weight of a male cocoon (MWMC) and the mean weight of a female cocoon (MWFC) (P<0.01). Also, the M*S hybrid showed a higher performance than other hybrids for the five traits of mean weight of a cocoon shell (MWCS), mean of cocoon shell percentage (MCSP), mean weight of a male cocoon shell (MWMCS), mean weight of a female cocoon shell (MWFCS), and the mean of female cocoon shell percentage (MFCSP) (P< 0.05). Also, the M*S hybrid showed the lowest value compared to other hybrids for the number of cocoons per liter (NCPL); the lower values of which are preferred (P<0.01). Based on the results of the present research, the priority of importing and rearing silkworm eggs in 2023 is suggested for BB*QA and M*S hybrids. Although the performance of these two hybrids with other hybrids, except for the 874×873 and 874×873 hybrids, is not significant in most of the examined traits, and they can still be considered as next import priorities.

Mitochondrial genome is an ideal model to study evolution and phylogenetic relationships. In this study, complete mitochondrial genomes of six species of Caspian sea sturgeon including Persian sturgeon, Russian sturgeon, Ship sturgeon, Sterlet sturgeon, Starry sturgeon and Beluga sturgeon along with separate nucleotide and amino acid sequences of 13 PCGs per each genome including ND1, ND2, ND3, ND4, ND5, ND6, ATP6, ATP8, COX1, COX2, COX3, ND4L and CYTB were retrieved from NCBI database and compared. The results obtained from sequence distance analysis by DNAStar software based on complete mitochondrion genome showed high genetic similarity (99 %) between Persian and Russian sturgeon. Also, the lowest similarity (95 %) was observed between Sterlet and Starry sturgeon. In phylogenetic analysis by MEGA7 software, two main clusters with two sub-clusters for one of the main clusters were identified. Persian and Russian sturgeon species were grouped in first sub-cluster, Ship and Sterlet species fall in the other sub-cluster and Starry sturgeon with Beluga formed a different distinct cluster. The results obtained from the comparison of the 13 PCGs sequences were similar to the sequences of the complete mitochondrial genomes. The most difference in nucleotide sequences were observed in CYTB, ATP6, ND2, ND5 and ND6 genes and the lowest difference for ND4L gene. The results obtained from the comparison of the 13 genes amino acid sequences were different as the order of the species was changed and 100 % genetic similarity were observed for some genes such as COX3 and ND4L genes. Based on the results of the present study, mitochondrial genome sequences could be used for phylogenetic analysis and clustering of different species of sturgeons. However, the accuracy of investigations by complete mitochondrial genomes is higher than the nucleotide sequences of the genes, and using the amino acid sequences is not suggested due to their codon nature.

Mitochondrial DNA (mitogenome) is a small and extra-chromosomal DNA, located in the cytoplasm and presents an ideal model to study evolution and genetic similarity. Classical phylogenetics is based on the morphological characteristics of the organisms, while in modern approaches, the phylogenetic distance and its related comparative methods are estimated based on observed genetic diversity in the studied genetic sequences. The aim of the present study was to investigate the divergence and percentage of genetic similarity along with the phylogenetic analysis of the seven main known species of wild and domestic sheep based on the complete sequence of the mitochondrial genome and the separate sequences of 13 protein-coding genes for each genome.
In the present study, complete mitochondrial genome sequences along with separate sequences of 13 protein-coding genes (including NADH ubiquinone oxidoreductase (ND1, ND2, ND3, ND4, ND5, and ND6), cytochrome c oxidase (COX1, COX2, and COX3), ATP synthase (ATP6 and ATP8), NADH dehydrogenase 4 L (ND4L), and cytochrome b (CYTB))  per each genome from six wild species of sheep including Asian Mouflon (Ovis orientalis), Bighorn (Ovis canadensis), Argali (Ovis ammon), Urial (Ovis vignei), Snow (Ovis nivicola), Dall (Ovis dalli), and domesticated species of sheep (Ovis aries) were retrieved from NCBI database and compared to each other. Mitochondrial genomes and genes’ alignment were accomplished by the MegAlign module of DNASTAR software and compared by the Clustal W method. The Sequence Distances sub-section of the MegAlign module of DNASTAR also was used for the analysis of complete genome and gene sequences divergence and similarity percentage. For phylogenetic analysis, complete mitochondrial genomes and protein-coding genes’ sequences were aligned using MEGA7 software. Based on the alignment, phylogenetic tree was constructed using the maximum likelihood method. The percentage of replicate trees of 1000 replicates of bootstrap test was used to represent the evolutionary history for the studied sheep species.
The results obtained from sequence distance analysis showed high genetic similarity (99.8 %) between Ovis orientalis and Ovis aries. Also, the lowest similarity (95 %) was observed between Ovis aries and Ovis dalli. In phylogenetic analysis, two main clusters, each with different sub-clusters were identified. Domesticated species of sheep (Ovis aries) along with Ovis orientalis, Ovis vignei, and Ovis ammon wild species of sheep formed distinct cluster, and Ovis nivicola, Ovis dalli, and Ovis Canadensis fell in a same cluster. In terms of all 13 protein-coding genes (including NADH ubiquinone oxidoreductase (ND1, ND2, ND3, ND4, ND5, and ND6), cytochrome c oxidase (COX1, COX2, and COX3), ATP synthase (ATP6 and ATP8), NADH dehydrogenase 4 L (ND4L) and cytochrome b (CYTB)), the results obtained from sequence distance similarity analysis and phylogenetic trees were similar to the sequences of the complete mitochondrial genomes. More than 99% of the genetic similarity for ND1, ND2, ND5, ND6, COX1, COX2, COX3, and ATP6 genes and 100% of the genetic similarity for ND3, ND4, ND4L, ATP8, and CYTB genes between domestic sheep (Ovis aries) and Mouflon (Ovis orientalis) sheep species were found. Also, similar to the results obtained from the comparison of the complete mitochondrial genome, the domestic sheep species (Ovis aries) showed the least genetic similarity with the Dall (Ovis dalli) and Bighorn (Ovis canadensis) wild sheep species in all 13 protein-coding genes. Similar to the results of phylogenetic analysis of complete mitochondrial genomes, domestic sheep species (Ovis aries) together with Ovies orientalis wild sheep were placed in the same sub-cluster and Ovis vignei and Ovis ammon species were placed in other distinct sub-clusters. In addition, the Ovis nivicola, Ovis dalli, and Ovis canadensis wild species fell in another main cluster, and in this cluster, Ovis dalli and Ovis canadensis were placed in a similar sub-cluster and Ovis nivicola in another distinct sub-cluster.
In previous studies, small parts of the mitochondrial genome (such as a part of the control region or cytochrome b gene) have been considered to show the genetic differences and phylogenetic relationships between different species and breeds of sheep. In the present study, the complete sequences of the mitochondrial genome along with the complete sequences of 13 protein-encoding genes per each genome in seven main species of wild and domestic sheep have been considered for examining genetic similarity and divergence and phylogenetic analysis for the first time. Based on the results obtained from the present study, mitochondrial genome sequences could be used for accurate phylogenetic analysis and clustering of different species of sheep.

Generally, genetic markers, associated with metabolic pathways, might be used in marker-assisted selection to improve production and reproduction traits in farm animals. Especially, some traits with low heritabilities, such as reproduction and health traits could not be easily improved by classic selection strategies. However, the use of genetic markers and marker-assisted selection are considered powerful tools for the genetic improvement of low-heritable traits. Thus, detection of genetic markers associated with production and reproduction traits is an effective way to save endangered indigenous breeds, such as the Markhoz goat, a mohair-producing breed in Iran. The thyroid hormone-responsive (THRSP) gene is a candidate gene involved in thyroid hormone functions and the lipogenesis process. This gene is a protein-coding gene, with two exons, located on chromosome 29 in goats. There are some reports on the association of THRSP with production traits in farm animals. There are limited studies on metabolic pathways of THRSP and its associations with important economic traits in small ruminants and no study on the association of THRSP and reproduction traits was found in the literature. The aim of the present study was the investigation of the THRSP gene polymorphism and its association with body weight and litter size traits in Markhoz goats.

A total of 140 blood samples of Markhoz goats were randomly collected from the Research and Breeding Station in Kurdistan province in western Iran. Genomic DNA was extracted from whole blood samples. A pair of primers were designed using the Primer 3 online software to amplify a 486 bp fragment in THRSP gene exon 1. The designed primers were as follows:Forward: 5’-AGTCTGCGGGACTCCATATG-3’ Reverse: 5’-AAAATGGGACAGGCCATGT-3’ Polymorphism of the amplified fragment was investigated using the single-strand conformational polymorphism (SSCP) method and sequencing of three random samples for each SSCP pattern. The observed sequences were aligned to the GenBank reference sequence using the MegAlign module of DNAStar software and compared based on the Clustal W method. The sequences were translated by the Translate section of the ExPASy website (us.expasy.org/translatetool). Associations of body weight traits, including birth weight, three-month, six-month, nine-month, and 12-month body weights, with the observed genotypes were investigated using a general linear model, fitting genotype, birth year, birth type, and dam age as the fixed factors. The association of the observed genotypes with litter size was investigated using a two-way Chi-squared test. The SAS 9.4 program was employed for the association analyses.

In the studied samples, two different SSCP patterns and two single-nucleotide polymorphisms (SNPs) were detected in 148 and 173 bp locations of the studied fragment, as g.148G>A (resulting in Arginine to Glutamine amino acids exchange) and g.173A>G (a synonymous mutation), both as heterozygous loci. In the studied population, the frequency of the double-homozygous genotype, GG/AA (0.743), was noticeably higher than the double-heterozygous genotype, which is GA/AG (0.257). The alleles G and A had high frequencies, both equal to 0.871 in the 148 and 173 bp loci, respectively. Both loci had a significant deviation from Hardy-Weinburg equilibrium (P<0.0001). Polymorphism of the studied fragment did not have any significant effect on body weight traits. A significant association was observed between the detected genotypes and litter size. Whereby, litter size in double-heterozygous does (1.21) was significantly higher than the double-homozygous individuals (1.04), (P = 0.015). The present study is probably the first report on the association of the THRSP gene with litter size in goats. The THRSP is a protein which involves in thyroid hormone function and therefore might affect many metabolic pathways. However, a significant association of the observed genotypes with prolificacy is probably due to the role of THRSP in lipids metabolism and the association of lipids metabolism with reproduction performance.

The THRSP exon 1 is polymorphic in Markhoz goats. The studied fragment did not have any significant associations with body weight traits, but it had a significant effect on litter size. Based on the results of this study, the THRSP gene could be considered a candidate gene for litter size, and the detected SNPs at 148 and 173 bp of the studied fragment, could be used for marker-assisted selection in Markhoz goats. However, more studies on possible associations between THRSP polymorphism and production and reproduction traits are still needed in other goat breeds.

The aim of the present study was to investigate the performance of the hybrids obtained by crosses of the six Japanese silkworm lines named IRA1, IRA3, IRA5, IRA7, IRA9, and IRA11 and six Chinese silkworm lines named IRA2, IRA4, IRA6, IRA8, IRA10, and IRA12. The new hybrids derived from these lines along with available commercial hybrids (as control groups) for six traits including cocoon weight, cocoon shell weight, cocoon shell percentage, best cocoon weight, pupation rate and best cocoon pupation rate were measured and recorded in spring 2020. The IRA7×IRA6 and IRA7×IRA12 hybrids had more performance in comparison with commercial hybrids in terms of productive traits including cocoon weight and cocoon shell weight (P < 0.01), but, when productive and viability traits (pupation rate and best cocoon pupation rate) were considered together in an evaluation index, they were not among the selected hybrids. Commercial 31×32 hybrid in terms of cocoon shell weight and cocoon shell percentage had more performance in comparison with the other hybrids (new and commercial) (p<0.01). Hybrids had a significant difference for pupation rate and best cocoon pupation rate (P < 0.01), and the IRA5×RA12, IRA1×IRA10 and IRA11×IRA6 hybrids showed the lowest mean for both traits in comparison to other hybrids (P < 0.01). The results obtained from the present study indicated that seven hybrids including IRA9×IRA2, IRA11×IRA2, IRA3×IRA6, IRA3×IRA2, IRA7×IRA4, IRA7×IRA10 and IRA7×IRA8 were greater than the minimum set for every six traits. Therefore, they can be used to supply the country's required silkworm eggs.

This study was conducted to investigate the polymorphisms of the Prion protein gene (PRNP) exon 3 in Mehraban and Romanov sheep. Blood samples were collected from 124 sheep (85 Mahraban and 39 Romanov). After DNA extraction, polymerase chain reactions (PCR) were performed to amplify a 173 bp fragment of the PRNP gene exon 3 using a specific pair of primers. Polymorphisms of the studied fragments were explored using single strand conformational polymorphism (SSCP) and DNA sequencing analysis. In both Mehraban and Romanov breeds, three different banding patterns (AA, AG and GG genotypes) along with a single nucleotide polymorphism (g.625A>G) were identified, that deduced one amino acid substitution (p.171R>Q). Three haplotypes including ARR/ARR, ARR/ARQ and ARQ/ARQ were identified, which the most frequency (61.2 and 46.15% in Mehraban and Romanov breeds, respectively) was related to the ARR/ARR haplotype with high resistance to scrapie disease. The results of current study regarding the similarity of polymorphism in PRNP gene of domestic and foreign breeds could be used in sheep breeding programs.