مجله سلول و بافت
سال سوم شماره 1 (بهار 1391)

Previous studies have shown that thyroid hormones are necessary for normal development of many tissues in the human body. So In this investigation, the effect of maternal hypothyroidism on neonatal skin development was studied using immunohistochemistry technique. Rats were divided in 4 groups hypothyroid, hyperthyroid, hypothyroid treated with thyroxin and control, each group containing 10 rats. 14 days before mating, hypothyroid, hyperthyroid and hypothyroid treated with thyroxin groups, were respectively exposed to Propylthiouracil (PTU) (50 mg/lit), levothyroxin 1 mg/lit and both PTU (50 mg/lit) and levothyroxin (1 mg/lit) simultaneously. After 14 days, blood test was taken from mothers and in the case of desired changes in hormone levels, rats were allowed to mate. After pregnancy and delivery, the dorsal skins of the 10 days old newborns were used for immunohistochemical studies. in this study, in most area of skin, significant increase of laminin expression in hypothyroid groups (p=0.002) and significant decrease of laminin expression in hyperthyroid groups (p=0.007) were observed. Also in treated hypothyroid with thyroxin rather than control group no significant difference was observed. Maternal hypothyroidism causes considerable changes in the expression of laminin in different areas of skin. While maternal hyperthyroidism causes opposite results in laminin expression. In fact, thyroid hormone causes negative regulation of laminin expression. There fore, rising of thyroid hormone levels leads to a decrease in laminin expression and overhand. So,changes in thyroid hormones level can cause various changes in different areas of newborns skin.

“The bulge activation hypothesis” has recently provided significant interest in the hair follicle cycle. One facet of this hypothesis suggests that the epithelial cells located at the base of the follicle are ‘transient amplifying, that limit the duration of the follicle’s growth phase. In this study, we investigate the pattern of cell division and proliferation of these cells and compared with those from upper part of follicle. To fulfill this task, epidermal cells from lower and upper vibrissa follicles were cultured after isolation and growth characteristics of these two cell types were measured and recorded over a period of weeks. Data provided here demonstrated that epidermal cells from lower region of follicle normally attached to the substrate and started dividing more slowly than their counterparts from the upper part of the follicle. In addition, although the majority of the basal cells failed to grow for extended periods and underwent terminal differentiation, a small subset of these cells grew as large single colonies for more than 10 weeks and they were able to be passaged several times. Contrary to the current dogma, we here showed that, at least in culture medium, some of basal hair follicle cells have a proliferative capacity which is much further than duration of the growth phase of follicle. Therefore, the termination of growth phase can not be related to the replicative potential of these cells.

The aim was to study the histology of somatic embryogenesis stages in Dorema ammoniacum D. using tissue cultures as an efficient method for propagation of the plants with restriction in cultivation.

Various explants were cultured on MS (Murashige and Skoog) medium containing 30 g l-1 sucrose and 7 g l-1 agar as well as supplemented with different concentrations of auxin and cytokinin. After eight weeks, different stages of development of somatic embryos in embryogenic callus were evaluated using histological method.

Out of different explants, only zygotic embryo was able to induce embryogenic callus. Presence of NAA (α-Naphthaleneacetic acid) increased callus induction and somatic embryogenesis. The highest callus formation was observed in MS medium supplemented with 1 mg/L NAA and 0.5 mg/L BA (N6-Benzyladenine). Different stages of somatic embryos including: globular, heart-shaped, torpedo and cotyledonus stages were observed in the prepared sections of callus.

Using zygotic embryo the in vitro somatic embryogenesis of Dorema ammoniacum D. was possible. In addition the histological examinations of embryogenic callus showed the existence of the different stages of embryonic development.

The aim of this research was the cloning and sequencing of gamma tocopherol methyl transferase gene (γ-tmt) from Memory 1 cv and transferring it into an oilseed plant such as canola, in the future studies for improving its nutritional value.

Total RNA was extracted from tomato fruit and cDNA constructed. By using specific primers the γ-tmt gene was amplified by PCR reaction and a 1089 bp fragment was produced. The amplified fragment and the pBluescript (SK-) vector were digested by XbaI. The ligation reaction was carried out by T4 ligase. E. coli competent cells were transformed by the resulting vector and recombinant colonies were identified using the white-blue screening assay.

The nucleotide sequence of the gene was determined and aligned with the available sequences recorded in the NCBI data bank. This sequence showed 98% similarity with the other recorded γ-tmts from Solanaceae family. Some changes in nucleotide sequence and the deduced amino acids were observed. The secondary and tertiary structures of the protein were predicted, using PSIpred software. A phylogenetic tree was also constructed for the protein product of the gene, using ClustalW.

The cloned cDNA of γ-tmt showed 98 % similarity with the recorded sequence from tomato cv Cerasiforme. Upon transfer of this gene into an oil seed plant such as canola, one can increase both its nutritional value and resistance to environmental stresses.

Reduction in ozone layer diameter as a result of increasing amount of pollutant causes veduced absorbance of sun light UV rays by this layer. Consequently, living organisms, such as plants are damaged. Occurring photochemical changes in plants are some adaptation, defense and confronting reactions against these damages. So, studies of these changes are important in higher plants. Studing ten cultivation groups seed and field plants consist of control and UV-C treated (totally 1-20 hours) of Coronilla varia L. were prepared in equal soil and cultivation condition. All of ninety-day old plants were used for chlorophyll-metry and flavonoid studies using 2-dimentional paper and thin layer chromatography methods. Chlorophyllmetric results showed a decrease in chlorophyll content in UV-C treated plants in comparison with the control. Comparising the leaf flavonoids showed that the number and kind of leaf flavonoid changes in UV-C treated plants in comparison with the control. These changes include Loteulin and Vitexin in treated plants and absence of them in control, Kaempferol presence in the treated field plants and absence of them in the others, Chrysin in the control and absence of them in the treated plants and the disappearing of Apeginin, Isorhamnetin, Rhamnetin, Narengenin, Myricetin and Quercetin in treated field samples. It is believed that phytochemical changes consisting of flavonoids kind and number varieties are defensive reactions of plant against physiological stresses such as UV-C.

The main goal of this research was to prepare three-dimensional matrix of gingival palate tissues and compare the behavior of bone marrow mesenchymal stem cells and blastema on the scaffolds. The tissues obtained from gingival surgeries in periodontal clinic were decellularized using detergents including sodium dodecyl sulfate and Triton X-100 then after washing and sterilization, were used as scaffold for culturing the rat’s mesenchymal stem cells. The scaffolds were studied by light and electron microscopy before and after 1, 2, and 4 weeks of culture. In addition the prepared scaffolds were assembled within the rings of blastema tissues from rabbit,s pinna. Then the scaffolds were similarly studied by histological techniques after 1, 2, and 4 weeks of culture. Scanning electron microscopy showed that epithelial matrix and collagen fibers in connective tissue remained intact. In both samples epithelium-like structures were observed. Also in the blastema cells migrating to the scaffolds cell secretion was also observed. Human gingival matrix can be a suitable scaffold for studying the cell behaviors. More research should be carried out to determine the identity of differentiated cells, which finally can improve our knowledge regarding the cell-matrix interactions.

In the present study, the antioxidant effect of vitamin C on decreasing the induced chromosomal damages by low-frequency electromagnetic field on bone marrow erythrocytes of male Balb/C mouse has been investigated. In this experimental study, 48 adult male mouse (Balb/C) were randomly divided into four equal groups: control, test 1, test 2 and test 3. Control group were kept in normal conditions and the mice in test1 and test3 groups were intraperitoneally injected with 50 mg / kg of vitamin C for 8 consecutive days. Then the mice of test 3 and test 2 groups after the fifth day were exposed to electromagnetic waves with frequency of 50 Hz and intensity of 50 Gauss for 4 days and 4 hours per day. The mice in all different groups were sacrificed and micronucleus test were performed on the bone marrow polychromatic erythrocytes. The data were analyzed using spss software and ANOVA test at level p < 0.05. The frequency of micronucleus in bone marrow polychromatic erythrocytes of test3 group (3.107± 0.276) in comparison with test 2 group (9.29 ± 0.881) showed a significant reduction (p < 0.001). Vitamin C caused significant decrease in induced chromosomal damages by low-frequency electromagnetic waves in bone marrow polychromatic erythrocytes of adult male Balb/C mouse.

As there was no studies available regarding the morphological structure of skin of (Barbus grypus) therefore this research work was performed to help the other studies such as histopathology of the fish.

Skin of the different part of the head of 20 Barbus grypus with 5mm thickness were removed and fixed in bouin solution. The routine procedures for preparation of tissues were followed. For transmission electron microscopic study, the samples after primary and post-fixation were dehydrated and embedded in resin. Then, thin sections 50 µm were prepared and stained with uranyl acetate.

according to histomorphological examination, skin of head, lip and barbel was made of epidermis and dermis which were located on a loose connective tissue called hypoderm. In histometric study, skin of studied area, was divided into different regions in (Barbus grypus) based on cells distribution. In the micrograph of TEM, goblet cells containing many mucus granule, spinous and club cells with hyper chromatin nucleus were observed, which presence of hyper chromatin nucleus was more obvious in the club cells.

The light and TEM studies on the skin in studied region of (Barbus grypus), showed there was differences and some similarity with the other reported species.