孕期应激对子代大鼠骨髓淋巴干细胞发育的影响

孕期应激对子代产生的影响是多方面的,这种影响是复杂的。研究表明,出生前的应激经历可导致出生后子代长期的免疫功能改变。这些改变追其根源与骨髓淋巴干细胞的改变有关。本文综述了大鼠孕期经历应激的子代骨髓淋巴干细胞所受的影响及免疫系统的相关改变,并根据现有的研究提出假说,为进一步研究孕期应激导致子代免疫系统改变的机理研究提供新的思路。     

Melanocyte stem cells: a melanocyte reservoir in hair follicles for hair and skin pigmentation

Most mammals are coated with pigmented hair. Melanocytes in each hair follicle produce melanin pigments for the hair during each hair cycle. The key to understanding the mechanism of cyclic melanin production is the melanocyte stem cell (MelSC) population, previously known as 'amelanotic melanocytes'. The MelSCs directly adhere to hair follicle stem cells, the niche cells for MelSCs and reside in the hair follicle bulge-subbulge area, the lower permanent portion of the hair follicle, to serve as a melanocyte reservoir for skin and hair pigmentation. MelSCs form a stem cell system within individual hair follicles and provide a 'hair pigmentary unit' for each cycle of hair pigmentation. This review focuses on the identification of MelSCs and their characteristics and explains the importance of the MelSC population in the mechanisms of hair pigmentation, hair greying, and skin repigmentation.     

Expression of GD2 and GD3 gangliosides in human embryonic neural stem cells

NSCs (neural stem cells) are undifferentiated neural cells endowed with a high potential for proliferation and a capacity for self-renewal with retention of multipotency to differentiate into neurons and glial cells. It has been recently reported that GD3, a b-series ganglioside, is a marker molecule for identifying and isolating mouse NSCs. However, the expression of gangliosides in human NSCs is largely unknown. In the present study, we analysed the expression of gangliosides, GD2 and GD3, in human NSCs that were isolated from human brains at gestational week 17 in the form of neurospheres, which are floating clonal aggregates formed by NSCs in vitro. Employing immunocytochemistry, we found that human NSCs were strongly reactive to anti-GD2 antibody and relatively weakly reactive to anti-GD3 antibody. Treatment of these cells with an organic solvent such as 100% methanol, which selectively removes glycolipids from plasma membrane, abolished the immunoreactivity with those antibodies, indicating that the reactivity was due to GD2 and GD3, but not to GD2-/GD3-like glycoproteins or proteoglycans. The immunoreactivity of human NSCs to antibody against SSEA-1 (stage-specific embryonic antigen-1), a well-known carbohydrate antigen of NSCs, was not decreased by the treatment with 100% methanol, indicating that SSEA-1 is mainly carried by glycoproteins and/or proteoglycans in human NSCs. Our study suggests that GD2 and GD3 can be marker gangliosides for identifying human NSCs.     

Seasonality and resource availability control bacterial and archaeal communities in soils of a temperate beech forest

It was hypothesized that seasonality and resource availability altered through tree girdling were major determinants of the phylogenetic composition of the archaeal and bacterial community in a temperate beech forest soil. During a 2-year field experiment, involving girdling of beech trees to intercept the transfer of easily available carbon (C) from the canopy to roots, members of the dominant phylogenetic microbial phyla residing in top soils under girdled versus untreated control trees were monitored at bimonthly intervals through 16S rRNA gene-based terminal restriction fragment length polymorphism profiling and quantitative PCR analysis. Effects on nitrifying and denitrifying groups were assessed by measuring the abundances of nirS and nosZ genes as well as bacterial and archaeal amoA genes. Seasonal dynamics displayed by key phylogenetic and nitrogen (N) cycling functional groups were found to be tightly coupled with seasonal alterations in labile C and N pools as well as with variation in soil temperature and soil moisture. In particular, archaea and acidobacteria were highly responsive to soil nutritional and soil climatic changes associated with seasonality, indicating their high metabolic versatility and capability to adapt to environmental changes. For these phyla, significant interrelations with soil chemical and microbial process data were found suggesting their potential, but poorly described contribution to nitrification or denitrification in temperate forest soils. In conclusion, our extensive approach allowed us to get novel insights into effects of seasonality and resource availability on the microbial community, in particular on hitherto poorly studied bacterial phyla and functional groups.     

Decreased 5-HT2C receptor binding in the cerebral cortex and brain stem during pancreatic regeneration in rats

The purpose of this study was to investigate the role of central 5-HT_2C receptor binding in rat model of pancreatic regeneration using 60–70% pancreatectomy. The 5-HT and 5-HT_2C receptor kinetics were studied in cerebral cortex and brain stem of sham operated, 72 h pancreatectomised and 7 days pancreatectomised rats. Scatchard analysis with [³H] mesulergine in cerebral cortex showed a significant decrease (p < 0.05) in maximal binding (B_max) without any change in K_d in 72 h pancreatectomised rats compared with sham. The decreased B_max reversed to sham level by 7 days after pancreatectomy. In brain stem, Scatchard analysis showed a significant decrease (p < 0.01) in B_max with a significant increase (p < 0.01) in K_d. Competition analysis in brain stem showed a shift in affinity towards a low affinity. These parameters were reversed to sham level by 7 days after pancreatectomy. Thus the results suggest that 5-HT through the 5-HT_2C receptor in the brain has a functional regulatory role in the pancreatic regeneration.     

Modulation of trophoblast stem cell and giant cell phenotypes: analyses using the Rcho-1 cell model

Trophoblast giant cells are located at the maternal-embryonic interface and have fundamental roles in the invasive and endocrine phenotypes of the rodent placenta. In this report, we describe the experimental modulation of trophoblast stem cell and trophoblast giant cell phenotypes using the Rcho-1 trophoblast cell model. Rcho-1 trophoblast cells can be manipulated to proliferate or differentiate into trophoblast giant cells. Differentiated Rcho-1 trophoblast cells are invasive and possess an endocrine phenotype, including the production of members of the prolactin (PRL) family. Dimethyl sulfoxide (DMSO), a known differentiation-inducing agent, was found to possess profound effects on the in vitro development of trophoblast cells. Exposure to DMSO, at non-toxic concentrations, inhibited trophoblast giant cell differentiation in a dose-dependent manner. These concentrations of DMSO did not significantly affect trophoblast cell proliferation or survival. Trophoblast cells exposed to DMSO exhibited an altered morphology; they were clustered in tightly packed colonies. Trophoblast giant cell formation was disrupted, as was the expression of members of the PRL gene family. The effects of DMSO were reversible. Removal of DMSO resulted in the formation of trophoblast giant cells and expression of the PRL gene family. The phenotype of the DMSO-treated cells was further determined by examining the expression of a battery of genes characteristic of trophoblast stem cells and differentiated trophoblast cell lineages. DMSO treatment had a striking stimulatory effect on eomesodermin expression and a reciprocal inhibitory effect on Hand1 expression. In summary, DMSO reversibly inhibits trophoblast differentiation and induces a quiescent state, which mimics some but not all aspects of the trophoblast stem cell phenotype.     

Stem/progenitor and intermediate cell types and the origin of human prostate cancer

Theories of cell lineage in human prostatic epithelium, based on protein expression, propose that basal and luminal cells: 1) are either independently capable of self-renewal or 2) arise from stem cells expressing a full spectrum of proteins (p63, cytokeratins CK5/14, CK8/18, and glutathione-S-transferase-pi [GST-pi]) similar to cells of the embryonic urogenital sinus (UGS). Such embryonic-like stem cells are thought to give rise to mature basal cells and secretory luminal cells. By single cell cloning of an immortalized, normal human prostate-derived, non-tumorigenic RWPE-1 cell line, we isolated and characterized two epithelial cell types, WPE-stem and WPE-int. WPE-stem cells show: i) strong, sixfold greater nuclear expression of p63; ii) nearly twofold greater expression of CK14; iii) threefold less CK18, and iv) low androgen receptor (AR) expression as compared with WPE-int cells. WPE-stem cells are androgen-independent for growth and survival. WPE-int cells express very low p63 and CK5/14, and high CK18. WPE-int cells are androgen-independent for growth and survival but are highly responsive as shown by androgen induction of AR and prostate specific antigen (PSA). Compared with WPE-int cells, WPE-stem cells are smaller and show more rapid growth. WPE-stem cells can grow in an anchorage-independent manner in agar with 4.5-fold greater cloning efficiency and as free floating "prostaspheres" in liquid medium; and express over 40-fold higher matrix metalloproteinase-2 activity. These results indicate that WPE-stem cells express several features characteristic of stem/progenitor cells present in the UGS and in adult prostatic epithelium. In contrast, WPE-int cells have an intermediate, committed phenotype on the pathway to luminal cell differentiation. We propose that in normal prostatic epithelium, cells exist at many stages in a continuum of differentiation progressing from stem cells to definitive basal and luminal cells. Establishment and characterization of clones of human prostatic epithelial cells provide novel models for determining cell lineages, the origin of prostate cancer, and for developing new strategies for tumor prevention and treatment.     

Diseases caused by <Emphasis Type="Italic">Ganoderma</Emphasis> spp. on perennial crops in Pakistan

Ganoderma applanatum (Pres. Wallr) Pat. and G. lucidum (Leyss. ex Fr.) Karst attack species of Pinus, Dalbergia, Artocarpus, Morus, Cedrus, Melia, Quercus, Populus and other trees in Pakistan causing stem, butt and root rot diseases. A research institution to manage the diseases of perennial crops in general and of trees yielding edible oil in particular such as coconut and oil palm needs to be established in Pakistan.