Iranian Journal of Biotechnology
Volume:5 Issue: 1, Winter 2007

Worldwide popularity of probiotic- microorganisms and their products on the one hand, and their general weak viability in food products (especially fermented types) as well as gastrointestinal conditions on the other hand, has encouraged researchers to innovate different methods of probiotics viability improvement. Microencapsulation of the probiotic cells is one of the newest and highly efficient methods, which is now under the especial attention and is being developed by various researchers. This article reviews the principles and methods of probiotic cell microencapsulation.

Biomimetic method was used to apply hydroxyapatite (HA) coating onto Ti6Al4V cylinders. This process is a physicochemical method in which a substrate is soaked in a solution simulating the physiological conditions, for a period of time enough to form a desirable layer of the calcium phosphate on the substrate. In the present study, specimens were soaked in 5, 10 M solutions of NaOH at temperatures of 60 or 80C for 24 and 72 h. Surface of samples were characterized using scanning electron microscopy (SEM) and thin film X-ray diffraction (TF-XRD). The optimum condition was found to be 72 h of soaking in 5 M NaOH at 80C. Specimens treated under these optimum conditions were subsequently heat-treated at 500, 600, and 700C for 1h in order to consolidate the sodium titanate hydrogel layer. Under the heat treatment condition of 600C for 1h and subsequent soaking in simulated body fluid (SBF), apatite formed within 3 days. It was observed that, apatite formation increased significantly, which is an indication of the materials ability for use as a load bearing implant.

Three Iranian native strains and three Japanese commercial lines of the silkworm Bombyx mori were analyzed using amplified fragment length polymorphism (AFLP) markers. A set of ten PstI/TaqI primer combinations amplified a total of 322 bands out of which 251 (%78) were polymorphic. Estimates of Neis gene diversity for all loci in individual strains and commercial lines indicated a higher degree of genetic similarity within Japanese commercial lines than the Iranian native strains. The highest and the least degree of gene diversity were related to the Khorasan Orange strain (h=0.1812) and P107 commercial line (h=0.0804), respectively. The dendrogran constructed using the unweighted pair-group method with arithmitic average based on nais genetic distance revealed two distinct groups as Khorasan native and Japanese commercial lines. The distinct clustering of these two sets of strains and lines reflects differences of the geographical origin and morphological, qualitative and quantitative traits associated with them.

The objective of this study was to estimate genetic parameters and to investigate the type of gene action in controlling androgenesis in wheat. Two wheat cultivars of Grebe and Houtman were reciprocally crossed with two synthetic genotypes of Do1 and Pol and then a complete set of the parents, F1, reciprocal F1 (RF1), F2 and back-cross generations (BC1 and BC2) of each cross were used for anther culture. The ratio of responding anthers, the ratio of albino and green regenerants, and the number of embryoids per each responding anther were determined for different generations of each cross. The results showed a wide genetic variation for embryoid induction and plant regeneration among the parental lines and their progenies. The genetic model of additive-dominance effects could explain the variation among the generation means for the traits, indicating that their inheritance was relatively simple. The genetic analysis also showed predominance of additive genetic effects in genetic control of embryoid induction and green plant regeneration, implying possible improvement of these traits by selection in plant breeding programs. Maternal effects were also found for embryoid induction. The narrow-sense heritability for responding anthers, green plants, albino plants, green plants to total regenerants, and embryoids per responding anther in different crosses varied from 41% to 77%, 64% to 92%, 67% to 84%, 40% to 67% and 33% to 65%, respectively. In conclusion, it seems that the improvement of green plant regeneration in anther culture technique can be achieved by appropriate breeding and selection programs

Adenoviruses (AdVs) types 40 and 41 are the causative agents of diarrhea in children. Hence, rapid sensitive and specific detection of these viruses are of clinical importance. The customary methods such as propagation of virus in cell culture suffer from limitations. Detection of immobilized amplified products in a one phase system (DIAPOPS) method has the potential to overcome these problems. A DIAPOPS method for detection of AdV types 40 and 41 was designed. Forward primers were covalently linked to the Nucleolink surface. After amplification of a 745 bp sequence of DNA binding protein gene, the amplified product was hybridized with the biotinylated probe. The hybrids were detected by the antibody-peroxidase conjugate. After optimization of the DIAPOPS conditions, 80 stool samples from children with clinical manifestation of viral diarrhea were tested. Their DIAPOPS results were compared with those of the conventional polymerase chain reaction (PCR) assay. Positive results were obtained in 11 samples. The comparison between conventional PCR and DIAPOPS showed a significant increase in sensitivity of the DIAPOPS test, 6 samples shown to be negative by conventional PCR, were demonstrated positive by DIAPOPS (p=0.00). The DIAPOPS assay presented in this study can provide a rapid, sensitive, specific and economic method for detection of viral infections. The assay can be performed for numerous samples simultaneously in a day. This DIAPOPS method can provide a practical and reliable tool for diagnosis of enteric adenoviruses. In addition, the risk of contamination in this assay is low.

A rapid and sensitive reverse transcription polymerase chain reaction (RT-PCR) and nested-PCR were used to detect bovine viral diarrhea virus 1 (BVDV-1) in bull semen. Selected primers could amplify a part of the 5UTR of the BVDV genome. A 294 bp DNA fragment was amplified and specificity of the results was confirmed by direct sequencing of the PCR product. Prior to RNA extraction, the seminal inhibitors were eliminated using a simple dilution method. Therefore, a sensitivity of 3102 50% tissue culture infective dose (TCID50) was achieved when experimentally infected semen was used for RNA extraction. In nested-PCR a 160 bp fragment was amplified and sensitivity of the test was increased to 3 TCID50. This technique can be used as a rapid and sensitive method of BVDV-1 detection in bovine semen.

Bovine viral diarrhoea virus (BVDV) is an important pathogen of dairy cattle. In this study, bulk milk samples representing a total of 4105 milking cows, from 18 dairy cattle herds in the suburb of Mashhad- Iran, were tested for presence of BVDV by the use of a nested reverse transcription polymerase chain reaction (Nested RT- PCR) assay. Non of the cows in the herds had been vaccinated against BVDV. RNA was extracted from somatic cell pellets of bulk milk tank samples. Oligonucleotide primers were selected based on the 5 untranslated region of the BVD virus genome. BVD virus was detected in 2 (11.1%) out of 18 samples, representing 742 lactating cows. These results indicate that nested RT-PCR analysis of bulk milk samples may provide a rapid and sensitive screening method for the detection of BVDV infections in non-vaccinated dairy cattle herds.