The role of maternal parathyroids and vitamin D3 metabolites in fetal growth and the deposition of glycogen reserves in the maternal and fetal liver in rats]

Thyro-parathyroidectomy of pregnant Rats at 12.5 days of gestation decreased maternal liver glycogen on 21.5 days of gestation and fetal weight as well as fetal liver glycogen stores. The graft of one parathyroid gland or the injection of 1 alpha-hydroxycholecalciferol in these thyro-parathyroidectomized mothers increased their liver glycogen stores at 21.5 days of gestation. These treatments also markedly increased both fetal weight and fetal liver glycogen stores. It was concluded that maternal 1,25-dihydorxycholecalciferol, which is synthesized under the control of parathyroid hormone secretion, controls fetal growth and liver glycogen stores. The mechanism of these effects (direct or indirect) requires further investigations.     

Molecular basis of base substitution hotspots in Escherichia coli.

In the lacI gene of Escherichia coli spontaneous base substituion hotspots occur at 5-methylcytosine residues. The hotspots disappear when the respective cytosines are not methylated. We suggest that the hotspots may result from the spontaneous deamination of 5-methylcytosine to thymine, which is not excised by the enzyme DNA-uracil glycosidase.     

干细胞修复与再生

近些年来，干细胞凭借其高度的发育可塑性，引起了医学与生物学界的极大兴趣。也许在不久的将来，我们人类体内所有受损或功能退化的组织都可以通过干细胞移植来进行修复与替换。从20世纪70年代初开始的骨髓造血干细胞移植已经让无数恶性血液病患者的生命得以延续，但最接近全能性的胚胎干细胞的研究尚存在着伦理学和成瘤性等问题，其它成体干细胞的研究也还处于起步阶段，在真正应用到f临床治疗前还需要进行大量的基础研究与临床前实验。     

Acetylsalicylic acid-induced morphological changes in the ductus arteriosus of the chick embryo

Summary The effect of acetylsalicyclic acid upon the ducti arteriosi of the embryonic chick was studied. A spectrum of gross malformations and histological findings associated with premature closure of the right ductus arteriosus is presented.This study was supported by grant No. HL18050, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland. The authors wish to extend their appreciation to John M. Opitz, University of Wisconsin Department of Genetics, for his generous support. This report was presented in part at the Fiftieth Scientific Sessions, American Heart Association Meetings, Miami, Florida, November 1977.     

The diversity of molecular motors: an overview

Rapid progress has recently been made in the identification and characterization of a large number of kinesin and myosin motor proteins. Recent work has uncovered roles for these motors in processes such as vesicle trafficking, cytoskeletal organization, and chromosome movements, to name a few. A series of reviews describing some of the significant advances in our understanding of the structure and function of myosins and kinesins is presented.     

Ganglioside-induced differentiation-associated protein-1 is mutant in Charcot-Marie-Tooth disease type 4A/8q21.

We previously localized and fine-mapped Charcot Marie Tooth 4A (CMT4A), the autosomal recessive, demyelinating peripheral neuropathy, to chromosome 8. Through additional positional cloning, we have identified a good candidate gene, encoding ganglioside-induced differentiation-associated protein-1 (GDAP1). We found three different mutations in four different Tunisian families-two nonsense and one missense mutation. How mutations in GDAP1 lead to CMT4A remains to be understood.