Cell-substratum and cell-cell interactions promote testicular peritubular myoid cell histotypic expression in vitro

Peritubular cells, prepared from seminiferous tubules from testes of 20-day-old-rats, were seeded onto different substrata and cultured under varying conditions. When plated onto polystyrene or glass surfaces, peritubular cells assumed a typical fibroblast-like cell shape and cell association pattern, together with a fibroblast-like migration behavior. They maintained high rates of proliferation even after achieving confluency. In contrast, when peritubular cells were plated onto a seminiferous tubule biomatrix (ST-biomatrix) surface, they spread to form a continuous cell layer having a myoepithelioid histotype similar to that of peritubular myoid cells in the intact seminiferous tubule. The characteristics of the myoepithelioid histotype described include a squamous, polyhedral cell shape; a cobblestone-like cell association pattern, with closely apposing or slightly overlapping cell borders, and a very low mitotic index. When peritubular cells were plated onto laminin, collagen, fibronectin, heparin, or a liver biomatrix, a fibroblast-like pattern resulted, indicating that ECM components listed and liver biomatrix are unable to substitute for ST-biomatrix in maintaining normal myoepithelioid characteristics in vitro. In cocultures of Sertoli cells plated on top of peritubular cells, the peritubular cells directly in contact with Sertoli cell aggregates developed a myoepithelioid histotype, whereas peritubular cells in regions not in direct contact had a fibroblast-like histotype. The data are discussed in relation to the possible role of cell-cell interactions, and cell-substratum interactions, in the acquisition and stabilization of the histotype of peritubular cells in the seminiferous tubule during development.     

Sequestration of arginine by polyphosphate in vacuoles of yeast (Saccharomyces cerevisiae)

The conditions for synthesis, purification, and properties of tryptophanase by a marine organism (Vibrio K-7) were studied. Tryptophanase was induced by tryptophan and its analogs, and partially repressed by 0.5% glucose or glycerol. NaCl (0.4M) was required for optimal growth and tryptophanase activity in whole cells. The enzyme was purified to 92% homogeneity by heat treatment, hydroxyapatite chromatography and fractionation with ammonium sulfate. This tryptophanase has been found to have kinetic properties similar to the tryptophanase from other microorganisms. It carries out both , -elimination reactions (using tryptophan, serine, cysteine and S-methyl-cysteine as substrates) and -replacement reactions (forming tryptophan from indole and serine, cysteine or S-methyl-cysteine). The enzyme has a sedimentation coefficient of 9.2S and requires pyridoxal 5-phosphate as a cofactor. The optimal pH for the tryptophanase reaction is pH 8.0.Nonstandard Abbreviations PLP pyridoxal 5-phosphate - TPase tryptophanase - TSase tryptophan synthase - DHase dehydratase - TCA tricarboxylic acid - BSA bovine serum albumin Preliminary reports of this work have been presented (M. J. Klug and R. D. DeMoss, Bacteriol. Proc. 1971, p. 132; D. D. Whitt and R. D. DeMoss, Abstr. Annu. Meet. Am. Soc. Microbiol. 1973, p. 148)     

MiRNA genes constitute new targets for microsatellite instability in colorectal cancer

Mismatch repair-deficient colorectal cancers (CRC) display widespread instability at DNA microsatellite sequences (MSI). Although MSI has been reported to commonly occur at coding repeats, leading to alterations in the function of a number of genes encoding cancer-related proteins, nothing is known about the putative impact of this process on non-coding microRNAs. In miRbase V15, we identified very few human microRNA genes with mono- or di-nucleotide repeats (n = 27). A mutational analysis of these sequences in a large series of MSI CRC cell lines and primary tumors underscored instability in 15 of the 24 microRNA genes successfully studied at variable frequencies ranging from 2.5% to 100%. Following a maximum likelihood statistical method, microRNA genes were separated into two groups that differed significantly in their mutation frequencies and in their tendency to represent mutations that may or may not be under selective pressures during MSI tumoral progression. The first group included 21 genes that displayed no or few mutations in CRC. The second group contained three genes, i.e., hsa-mir-1273c, hsa-mir-1303 and hsa-mir-567, with frequent (≥ 80%) and sometimes bi-allelic mutations in MSI tumors. For the only one expressed in colonic tissues, hsa-mir-1303, no direct link was found between the presence or not of mono- or bi-allelic alterations and the levels of mature miR expression in MSI cell lines, as determined by sequencing and quantitative PCR respectively. Overall, our results provide evidence that DNA repeats contained in human miRNA genes are relatively rare and preserved from mutations due to MSI in MMR-deficient cancer cells. Functional studies are now required to conclude whether mutated miRNAs, and especially the miR-1303, might have a role in MSI tumorigenesis.     

Nitrogen and phosphorus accumulation and cycling by Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae)

In 1980, the seasonal changes in nitrogen and phosphorus concentration of various plant parts of Nymphoides peltata (Gmel.) O. Kuntze, together with aspects of nitrogen and phosphorus cycling by this species were studied in an oxbow lake of the river Waal (The Netherlands). The nitrogen and phosphorus stores of the water, seston, sediment and macrophyte compartments were assessed each month.The underground Nymphoides structures had high nitrogen and phosphorus concentrations before and after the main growing season, while during summer the aboveground plant parts had high nutrient contents. Nymphoides peltata accumulated maximum amounts of nitrogen (334 mmol m⁻²) and phosphorus (56.6 mmol m⁻²) in July. The upper layers of the bottom appeared to be an enormous nutrient reservoir (94–99% of total) of which the largest part was not directly available to Nymphoides. Nutrient uptake from the sediments by N. peltata is suggested by the fact that the bottom and/or interstitial water of the sample station devoid of rooted macrophytes, contained higher concentrations of nitrogen and phosphorus than that of the Nymphoides stands. The annual flux of nutrients from Nymphoides to the detritus compartment was estimated to be ca. 1200 mmol nitrogen and 164 mmol phosphorus per m² of littoral. During breakdown of the detritus there was a relatively fast net conversion of organically bound nitrogen and phosphorus to inorganic forms, especially at higher temperatures.Nymphoides has the potential to function as an important nitrogen and phosphorus pump, which regenerates sediment nutrients.     

Chemotaxonomical investigations of theSymphytum officinale polyploid complex andS. asperum (Boraginaceae): The pyrrolizidine alkaloids

By means of thin layer chromatography in conjunction with mass spectrometry the pyrrolizidine alkaloid patterns derived fromSymphytum asperum, several cytotypes ofS. officinale agg. and the artificial hybrids of the former taxa, were compared. The obtained patterns were not essentially affected by variation in cytotype, harvesting times and -location of plants. Lycopsamine, acetyl-lycopsamine and symphytine or their isomers were generally found in theS. officinale cytotypes, echimidine and symphytine inS. asperum. The interspecific hybrids contained all alkaloids mentioned. The definite lack of echimidine in the 2 n=40 cytotype proves that it is conspecific withS. officinale and does not belong to a hybrid-swarmS. asperum × S. officinale with 2 n=48. Part I of this series of contributions.     

Prevalence of Thelohania solenopsae infected Solenopsis invicta newly mated queens within areas of differing social form distributions

Newly mated queens (NMQs) originating from monogyne red imported fire ant (Solenopsis invicta) colonies and following a mating flight, initiate new colonies by sealing themselves in a nuptial chamber and relying solely on their own fat and crop reserves, as well as no longer needed wing muscles to rear their first workers (claustral colony foundation). This method of colony-founding is rarely successful for polygyne-derived NMQs, whose low weight critically limits the number of first workers they are able to produce. However, this observation may be confounded by the parasitic microsporidium, Thelohania solenopsae, thus far found to persist only in association with polygyne colonies. Infections of this microsporidium reduce the weight of female alates and may explain why polygyne NMQs are unlikely to successfully found colonies claustrally. NMQs collected following mating flights in Gainesville and Ocala, Florida were sorted by weight, checked for insemination and T. solenopsae infection. Insemination levels were greater than 90% for all weight classes at both collection sites and were not related to infection. Infection levels were lower in Gainesville than Ocala, averaging 1.67% and 14.14%, respectively. Polygyne-derived NMQs collected in Ocala, defined here as weighing 12mg (social form correctly assigned in 85% of samples examined by PCR), had the highest infection levels, 25.37% (17/67) in 2003 and 21.43% (6/28) in 2004. We conclude that infection by T. solenopsae cannot be completely responsible for the inability of polygyne NMQs to claustrally establish colonies.     

Dynamics of immune cell recruitment during West Nile encephalitis and identification of a new CD19+B220-BST-2+ leukocyte population

West Nile virus (WNV) is an emerging neurotropic flavivirus. We investigated the dynamics of immune cell recruitment in peripheral tissues and in the CNS during WNV encephalitis in an immunocompetent mouse model. In the periphery, immune cell expansion can successfully limit viremia and lymphoid tissue infection. However, viral clearance in the periphery is too late to prevent viral invasion of the CNS. In the CNS, innate immune cells, including microglia/macrophages, NK cells, and plasmacytoid dendritic cells, greatly expand as the virus invades the brain, whereas B and T cells are recruited after viral invasion, and fail to control the spread of the virus. Thus, the onset of WNV encephalitis was correlated both with CNS viral infection and with a large local increase of innate immune cells. Interestingly, we identify a new immune cell type: CD19(+)B220(-) BST-2(+), which we name G8-ICs. These cells appear during peripheral infection and enter the CNS. G8-ICs express high levels of MHC class II, stain for viral Ag, and are localized in the paracortical zone of lymph nodes, strongly suggesting they are previously unidentified APCs that appear in response to viral infection.