Densin is a novel cell membrane protein of Sertoli cells in the testis

Cell-cell interactions between Sertoli cells and germ cells are crucial for the maturation of germ cells in spermatogenesis but the structural and functional aspects of the interactions remain to be fully elucidated. Densin is a junction protein suggested to play a role in establishment of specific cell-cell contacts in the post-synaptic densities of the brain and the slit diaphragm of the kidney podocyte. In the present study, densin was discovered to be expressed in the testis of the man and the mouse. Expression of densin at the gene and the protein level was studied by using RT-PCR and Western blotting analyses, and the localization of densin was explored with immunofluorescence staining. RT-PCR and Western blotting analyses showed that densin is expressed at the gene and the protein levels. Immunofluorescence staining localized the expression of densin to the cell membranes of Sertoli cells suggesting that densin may be an adherens junction protein between Sertoli cells and developing germ cells. Densin is a novel testicular protein expressed in the cell membranes of Sertoli cells. Its functional role remains to be assessed.     

毛竹bHLH转录因子的鉴定及其在干旱和盐胁迫条件下的表达分析

以毛竹（Phyllostachys edulis（Carr.）Lehaie）为材料,利用生物信息学方法,在基因组水平上对其bHLH基因家族成员进行鉴定和分析,并对不同组织中该基因的表达模式以及部分基因在干旱和高盐胁迫条件下的表达情况进行研究。结果显示：在毛竹中共鉴定出153个具有完整保守结构域的bHLH基因家族成员（PebHLH001~PebHLH153）,这些基因内含子数量为0~14,其中137个基因的启动子均含有与干旱、盐胁迫相关的顺式作用元件;PebHLHs编码的蛋白长度为134~1401 aa;bHLH家族成员的系统进化分析结果表明,153个PebHLHs可被分为17个亚类,其中C亚类的成员数量最多,为42个;基于转录组数据的表达谱分析结果发现,有151个PebHLHs在毛竹不同组织和不同生长发育时期有不同程度的表达量;实时荧光定量PCR实验结果显示,在干旱和盐胁迫处理后,分别有14和13个PebHLHs基因的表达量上调,分别有2和3个表达量下调,但表达模式存在一定差异,说明他们在应答干旱和盐胁迫过程中可能发挥不同的作用。     

Experimental pitfalls in evaluating vectorial protein secretion in vitro; Sertoli cell secretion of androgen-binding protein and transferrin in two-compartment culture chambers

Summary We examined the influence of various Millipore filter pretreatments on the amounts of androgen-binding protein (ABP) and transferrin (Trf) found in the outer (OC) and inner (IC) compartment of two-compartment Sertoli cell (Sc) cultures. When Sc were cultured on untreated Millipore filters, less than 10% of ABP was found in OC during 3 initial culture days compared to similar cultures on pretreated filters. Most of the glycoprotein was shown to be bound by the filters. Pretreatment of Millipore filters with 5% bovine serum albumin (BSA) or 2% fetal bovine serum (FBS) maximally saturated the nonspecific protein-binding sites resulting in OC:IC ratio of ABP similar to that found in cultures on polycarbonate membranes, which exhibit very low protein-binding capacity. In contrast to ABP, about 40% of Trf was bound by the Millipore filter on Day 1, with only trace amounts bound thereafer. These differences were due to much higher secretion rate of Trf than ABP, resulting in a relatively smaller fraction of Trf bound to the filter. Again, the nonspecific binding of Trf was greatly reduced by filter pretreatment with 5% BSA or 2% FBS. It is concluded that complete saturation of protein-binding sites of cellulose ester supports is necessary for reliable evaluation of vectorial protein secretion by Sc and other polarized epithelial cells maintained in this type of culture. The implications of partial saturation of protein-binding sites of culture support in interpreting experimental results are discussed. This work was supported in part by grant HD-17802 (A.S.) from the National Institutes of Health, Bethesda, MD.     

Sertoli cells in the testis of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani (Amphibia: Gymnophiona): light and electron microscopic perspective

The caecilians have evolved a unique pattern of cystic spermatogenesis in which cysts representing different stages in spermatogenesis coexist in a testis lobule. We examined unsettled issues relating to the organization of the caecilian testis lobules, including the occurrence of a fatty matrix, the possibility of both peripheral and central Sertoli cells, the origin of Sertoli cells from follicular cells, and the disengagement of older Sertoli cells to become loose central Sertoli cells. We subjected the testis of Ichthyophis tricolor (Ichthyophiidae) and Uraeotyphlus cf. narayani (Uraeotyphliidae) from the Western Ghats of Kerala, India, to light and transmission electron microscopic studies. Irrespective of the functional state of the testis, whether active or regressed, Sertoli cells constitute a permanent feature of the lobules. The tall Sertoli cells adherent to the basal lamina with basally located pleomorphic nuclei extend deeper into the lobule to meet at the core. There they provide for association of germ cells at different stages of differentiation, an aspect that has earlier been misconceived as the fatty matrix. Germ cells up to the 4-cell stage remain in the intercalating region of the Sertoli cells and they are located at the apices of the Sertoli cells from the 8-cell stage onwards. The developing germ cells are intimately associated with the Sertoli cell adherent to the basal lamina until spermiation. There are ameboid cells in the core of the lobules that appear to interact with the germ cells at the face opposite to their attachment with the Sertoli cells. Adherence of the Sertoli cells to the basal lamina is a permanent feature of the caecilian testicular lobules. The ameboid cells in the core are neither Sertoli cells nor their degeneration products.