Blastocyst implantation in the chinese hamster (Cricetulus griseus)

Embryonic development of the Chinese hamster (Cricetulus griseus) was studied from the onset of implantation to the formation of the parietal yolk sac placenta. Implantation began on day 6 of pregnancy, when the embryo became fixed to the uterine luminal epithelium. At this time there was no zona pellucida, and microvilli of the trophoblast and uterine epithelium were closely apposed. Stromal cells immediately adjacent to the implantation chamber began to enlarge and accumulate glycogen. By day 7 the mural trophoblast penetrated the luminal epithelium in discrete areas. The trophoblast appeared to phagocytize uterine epithelial cells, although epithelium adjoining the points of penetration was normal. In other areas nascent apical protrusions from the uterine epithelium indented the surface of the trophoblast. The epiblast had enlarged and both visceral and parietal endoderm cells were present. The well-developed decidual cells were epithelioid and completely surrounded the implantation chamber. On day 8 the uterine epithelium had disappeared along the mural surface of the embryo. The embryonic cell mass was elongated and filled the yolk sac cavity. Reichert's membrane was well developed. The uterine epithelial basal lamina was largely disrupted, and the trophoblast was in direct contact with decidual cells. Primary and secondary giant trophoblast cells were present and in contact with extravasated maternal blood. The mural trophoblast formed channels in which blood cells were found in close proximity to Reichert's membrane. Decidual cells were in contact with capillary epithelium and in some cases formed part of the vessel wall. Structural changes occurring in the embryo and endometrium during implantation in the Chinese hamster are described for the first time in this report and are compared to those described for some other myomorph rodents.     

山医群体中国地鼠自发的遗传性糖尿病模型

经过五年的工作,我们在一般实验室条件下,对野生地鼠进行驯养和近亲交配,繁育成目前国内较大的中国地鼠山医群体,并建成自发的遗传性糖尿病模型。模型的特点是:动物为非肥胖型,血糖呈中、轻度增高,血清胰岛素浓度表现多样,胰岛病变程度不一,糖尿病发病率受饮食因素影响,且具有多基因遗传特点。相似于人类非胰岛素依赖型糖尿病(NIDDM)。     

Neurogenesis in the basal forebrain of the Chinese hamster (Cricetulus griseus). I. Time of neuron origin.

Summary The time of neuron origin has been determined in the basal ganglia and related basal forebrain structures of the Chinese hamster with the aid of ³H-thymidine autoradiography. Large-celled structures like the globus pallidus, nucleus of the horizontal limb of the diagonal band of Broca as well as large cells in the rostral part of the substantia innominata, in the caudate-putamen-complex and in the olfactory tubercle arise early (E₁₂–E₁₆), whereas medium-sized and small cells in the basal forebrain have a persistent origin over a much longer period. Neuron formation in the basal forebrain persists decrementally until P₄. A clear caudorostral spatiotemporal gradient as well as a distinct outside-in gradient have been observed in the caudate-putamen-complex. Medium-sized neurons in the neostriatum and in the nucleus accumbens, generated simultaneously, are usually arranged in scattered clusters. The present data on time of neuron origin strongly support other evidence which points to the conclusion that the nucleus accumbens can be considered as a ventromedial extension of the caudate-putamen-complex.     

Stable Expression in Chinese Hamster Ovary Cells of Mutated Tau Genes Causing Frontotemporal Dementia and Parkinsonism Linked to Chromosome 17 (FTDP-17)

Extensive neuronal loss and aggregation of tau as cytoplasmic inclusions in neurons and glial cells in selected cortical and subcortical regions is the most striking characteristic of frontotemporal dementia and parkinsonism linked to chromosome 17, which is caused by exonic or intronic mutations in the tau gene. Here, we examined the effects of four exonic mutations in four-repeat tau using stably transfected Chinese hamster ovary cells. The proportion of polymerized tubulin was the largest in the P301L transfectant. G272V and P301L transfectants showed greater instability of microtubules in the presence of Colcemid than wild-type tau, V337M, or R406W transfectants. Thus no distinct phenotypes were shared by the mutant tau transfectants with regard to microtubule assembly and stability. Unexpectedly, R406W showed low and negligible levels of phosphorylation at Thr 231 and Ser 396, respectively, in the transfectant. This presents a sharp contrast to the observation that tau aggregates in R406W-affected brains are heavily phosphorylated at these two sites. This result suggests that hyperphosphorylation at these sites cannot occur in the tau R406W bound to microtubules, and thus that the hyperphosphorylated species of tau may be generated only after disruption of microtubules.     

Expression of Secreted Immunoglobulin Heavy Chain Genes and Immunoglobulin-Secreting Cells in Human Lymphocytes

The numbers of immunoglobulin-secreting cells in peripheral blood mononuclear cells and the expression of mRNA for secreted type of immunoglobulin heavy chains were investigated in healthy children, compared with the percentages of surface immunoglobulin-bearing cells and the expression of mRNA for membrane-bound type of immunoglobulin heavy chains, respectively. Although a difference between expression of μs mRNA and μm mRNA was unclear, μmRNA was well transcribed. The expression of γs mRNA or αs mRNA was markedly higher than that of γm mRNA or αm mRNA. However, although the detection methods could be of different sensitivities, the percentage of IgM-, IgG-, or IgA-secreting cells was markedly low, compared with the percentage of surface IgM-, IgG-, or IgA-bearing cells, respectively. Therefore, additional regulation of the pattern of the immunoglobulin gene expression may be exerted at the translational and post-translational stages.     

Effect of photoperiod on pineal gland volume and pinealocyte size in the chinese hamster,Cricetulus griseus

Male adult (200-day-old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod-induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of animals.     

Cloning and Characterization of Chinese Hamster CDC7 (ChCDC7)

The Cdc7 serine/threonine kinase is essential for entry into and to traverse through S phase. We have cloned the putative Chinese hamster CDC7 (ChCDC7) cDNA that is capable of encoding a protein of 572 amino acids with predicted molecular mass of 62.6 kDa. The ChCdc7 protein includes all 11 kinase domains that are conserved among the Cdc7-related protein kinases. In addition, the ChCdc7 protein kinase contains at least two kinase inserts that show substantial identity to those of huCdc7p. Overall, ChCdc7p shares 81, 56, 30, and 27% amino acid sequence identity with the Cdc7-related proteins of human, Xenopus, Saccharomyces cerevisiae, and Schizosaccharomyces pombe, respectively. Although the levels of ChCDC7 mRNA and protein are relatively constant throughout the cell cycle in the cycling cells, they are extremely low in the cells synchronized in the quiescent stage (i.e., G0). When cells in G0 are released into the cell cycle, the levels of ChCDC7 mRNA and protein increase slowly until the cells reach the G1/S border, at which time the increase is rapid. This suggests that a number of signal transduction pathways may have to be activated prior to CDC7 gene expression. Interestingly, the ChCdc7-GFP fusion protein formed discrete granules in the nuclei of cells arrested in early S phase by aphidicolin, raising the possibility that ChCdc7p is part of the replication factory.     

Expression of Four Genes of Bacteriophage MB78 from Contiguous Open Reading Frames: The Genomic Organization as Deduced by Sequence Analysis

Four proteins of bacteriophage MB78 having apparent molecular weights as 35, 14, 21 and 16 kDa are expressed from 3.9 kb SalI-HindIII fragment located almost in the middle of the phage genome. Analysis of the sequence supported by some experimental evidences suggest that these four proteins are expressed from polycistronic message without any intercistronic gap. Stop and start codons of consecutive ORFs overlap and rare initiation codons are used. Computer analysis of the sequence suggests the presence of two more open reading frames within the ORFs of 35 and 16 kDa proteins but in the opposite orientation, i.e. in the complementary strand.