Fish skin bacteria: Colonial and cellular hydrophobicity

Dental plaque is a complex community of bacteria coexisting in an environment frequently limited by carbon and energy sources. UnlikeStreptococcus mutans, other oral streptococci such asS. milleri andS. sanguis have an absolute requirement for and actually consume all available arginine when grown glucose limited in a chemically defined medium. The conditions, particularly in terms of arginine concentration, under which the dental plaque bacteriaS. mutans andS. milleri would coexist under glucose-limiting conditions were investigated. The minimum level of arginine supporting optimal growth ofS. milleri was found to be ca. 50M, and above this level these strains outcompetedS. mutans. However, coexistence withS. mutans could be achieved at arginine levels of 14–40M, depending upon theS. milleri andS. mutans strains used. Under such dual limitation,S. milleri was unable to respond to glucose pulses but did respond to pulses of arginine and arginine plus glucose. One of the twoS. milleri strains did not tolerate low pH. In contrast,S. mutans did not tolerate high pH whereasS. milleri was unaffected. This is relevant to dental plaque where arginine catabolism produces a pH rise. Additionally, arginine is an important nutrient since it can be used as an energy source by some oral streptococci.     

Interspecific variation in arrangement and morphology of micrasters of Tethya species (Porifera,Demospongiae)

Summary A new distinctive feature between the two Mediterranean species of Tethya, T. aurantium and T. citrina has been found in the body arrangement of different types of micrasters. Contrary to the previous assumptions, T. aurantium has two clearly distinct categories of micrasters: the chiaster-tylaster in the cortex and the larger, slender oxyaster in the choanosome. T. citrina has only slightly differentiated micraster sets in the cortex and choanosome; in the latter the shape of micrasters is close to that of oxyasters. SEM analysis shows that differences in micraster shape depend on the cylindrical or conical form of rays and on the distribution, density and strength of the microspines along their axis. The relationship between the degree of micraster differentiation and the development of the cortex in the two species is discussed.     

Differential distribution of3H dihydrotestosterone and3H estradiol nuclear binding sites in mouse male accessory sex organs

Summary The distribution of specific nuclear binding sites for androgens and estrogens in the male accessory sex organs of the mouse was assessed by autoradiography with³H dihydrotestosterone (³H DHT) and³H estradiol (³H E₂). With³H DHT nuclear labeling differed among the epithelia of the organs. It was high in seminal vesicle and ampullary gland, moderate in ventral prostate, urethral gland, prostatic excretory ducts and the ampulla ductus deferentis, low in dorsal prostate and low or absent in coagulation gland. With³H E₂, in contrast, epithelial nuclear labeling was high only in coagulation gland, moderate or low in seminal vesicle, low or absent in ventral and dorsal prostate and absent in ampullary gland and ampulla ductus deferentis. In the lamina propria of all organs nuclear labeling with³H DHT was generally moderate and existed only in some cells, with the highest number in the ampulla ductus deferentis. With³H E₂, nuclear labeling in the lamina propria showed a high intensity in all organs, except in ventral and dorsal prostate which remained unlabeled. Many labeled cells were found in the deferent duct and its ampulla, while in the other organs only a few cells showed nuclear labeling with³H E₂. In the smooth muscle sheath of all organs, some muscle cells were moderately labeled with³H DHT, but not with³H E₂. The results indicate the presence of nuclear receptors in male accessory sex organs for both dihydrotestosterone and estradiol. The differential patterns of³H DHT and³H E₂ nuclear uptake suggest differential sensitivities of the individual organs and their tissue compartments for androgens and estrogens. Supported by PHS grant NSO9914 to W.E.S. and Deutsche Forschungsgemeinschaft Dr94/4 to U.D. The work of Dr. Schleicher and his stay in Chapel Hill were additionally sponsored by Studienstiftung des Deutschen Volkes and Boehringer-Ingelheim Fonds     

Autoradiographic studies with 3H dihydrotestosterone in the brain of sex reversed mice,heterozygous for androgen insensitive testicular feminization (Tfm)

Summary Specific binding sites for ³H dihydrotestosterone are demonstrated by autoradiography in brain nuclei of sex reversed mice heterozygous for testicular feminization (Tfm) which are phenotypically intersexes with testes and accessory sex glands that consist of a mosaic of androgen insensitive Tfm cells which lack specific dihydrotestosterone binding and androgen sensitive normal cells. The nuclear group evaluated include: nucleus (n.) septi lateralis, n. interstitialis striae terminalis, n. medialis amygdalae, the hypothalamic n. arcuatus, n. ventromedialis lateralis, n. premammillaris ventrialis, n. preopticus medialis, and nuclei of the cranial nerves VII, X, and XII. In the sex reversed males and the female, used as controls, the frequency of neurons with specific DHT binding show a distinct male-female difference in the caudal part of the arcuate nucleus. In the sex reversed Tfm heterozygotes, in all brain nuclei studied, the frequency of labeled neurons is reduced. The extent of reduction of androgen binding in the different brain nuclei varies among as well as within individual sex reversed Tfm heterozygotes, suggesting variations of the ratio of normal to Tfm neurons in sex reversed Tfm heterozygotes. The differentially reduced androgen binding of different brain systems corresponds to a differentially reduced androgen dependent behaviour reported in the literature.Supported by US PHS grant NSO9914 to W.E.S. and Deutsche Forschungsgemeinschaft Dr94/4 to U.D.. The work of Dr. Schleicher and his stay in Chapel Hill were sponsored by Studienstiftung des Deutschen Volkes and Boehringer-Ingelheim Fonds     

Welcome aboard: are birds migrating across the Mediterranean Sea using ships as stopovers during adverse weather conditions?

Birds use stopovers during migration to interrupt endurance flight in order to minimize immediate and/or future fitness costs. Stopovers on ships is considered an exceptional and anecdotal event in the ornithological literature. This does not match the experience we had in the summer of 2021, during an oceanographic campaign in the Central Mediterranean, when we regularly observed on average 2.8 birds, of at least 13 species, stopping on board during the 25 days of the campaign. The median stopping time was 42 min, ranging from a few minutes to overnight stays on board. The probability of finding a bird stopping aboard increased with wind force and cloud cover. Birds also stopped more often in a headwind and did not stop when the wind came from different directions other than the headwind. The Central Mediterranean is one of the busiest sea routes in the world, combining the mean daily number of birds on board with the thousands of ships that pass through it during the 3 months of summer migration; we estimate that nearly 4 million birds could use ships as stopover sites. This behaviour may represent a modern-day strategy that uses ships as stopovers in the event of adverse weather conditions or could act as an ecological trap, increasing the mortality of migrants. This phenomenon deserves more research attention and further studies recording body condition and tagging of individuals on board would be informative.     

Autoradiographic studies with 3H 1,25 (OH)2 vitamin D3 and 3H 25 (OH) vitamin D3 in rat parathyroid glands

Summary After injection of radiolabeled 1,25 (OH)₂ vitamin D₃, nuclear concentration of radioactivity is observed in parenchymal cells of the parathyroid gland in pregnant, adult male, and 10-day male neonatal rats. In competition studies with unlabeled 1,25 (OH)₂ vitamin D₃, but not with 25 (OH) vitamin D₃, nuclear uptake is prevented. Experiments with ³H 25 (OH) vitamin D₃, in contrast to ³H 1,25 (OH)₂ vitamin D₃, do not show nuclear concentration in cells of the parathyroid. The results of the autoradiographic studies suggest the presence of receptors for a direct effect of 1,25 (OH)₂ vitamin D₃ on the parathyroid gland for modulation of parathyroid hormone secretion.     

Immunocytochemical demonstration of nerve growth factor and histofluorescence of catecholaminergic nerves in the salivary glands of diabetic mice

Summary Nerve growth factor (NGF) was localized in the submandibular, sublingual, and parotid salivary glands of male and female diabetic mice and their normal littermates by immunoperoxidase staining usingp-phenylenediamine-pyrocatechol as a chromogen for the cytochemical demonstration of peroxidase activity. In the normal male submandibular gland, immunoreactive NGF was localized in the apical regions of granular, intercalated and collecting duct cells, while in the normal female submandibular gland, NGF was present throughout the cytoplasm of granular duct cells. The localization of NGF in the diabetic male and female submandibular glands was similar and resembled that of the normal female. NGF immunoreactivity was also observed in the striated duct cells in the sublingual and parotid glands of all four types of mice.The sympathetic innervation of the submandibular glands of normal and diabetic mice was demonstrated using glyoxylic acid-induced histofluorescence. The pattern of sympathetic innervation and the intensity of catecholamine fluorescence was consistently different in the four types of mice. In the normal male submandibular gland the fluorescence was very intense, particularly in nerves adjacent to the granular ducts. In the normal female submandibular gland, the fluorescence was weak, while in the diabetic male and female the fluorescence was moderate.The correlation between the intensity of the immunocytochemical staining for NGF and the catecholamine fluorescence adjacent to the granular ducts suggests a trophic influence of the NGF-containing granular ducts on their sympathetic innervation.