Nitrobacter winogradskyi cytochrome c oxidase genes are organized in a repeated gene cluster

Cytochrome c oxidase (EC 1.9.3.1) is one of the components of the electron transport chain by which Nitrobacter, a facultative lithoautotrophic bacterium, recovers energy from nitrite oxidation. The genes encoding the two catalytic core subunits of the enzyme were isolated from a Nitrobacter winogradskyi gene library. Sequencing of one of the 14 cloned DNA segments revealed that the subunit genes are side by side in an operon-like cluster. Remarkably the cluster appears to be present in at least two copies per genome. It extends over a 5–6 kb length including, besides the catalytic core subunit genes, other cytochrome oxidase related genes, especially a heme O synthase gene. Noteworthy is the new kind of gene order identified within the cluster. Deduced sequences for the cytochrome oxidase subunits and for the heme O synthase look closest to their counterparts in other -subdivision Proteobacteria, particularly the Rhizobiaceae. This confirms the phylogenetic relationships established only upon 16S rRNA data. Furthermore, interesting similarities exist between N. winogradskyi and mitochondrial cytochrome oxidase subunits while the heme O synthase sequence gives some new insights about the other similar published -subdivision proteobacterial sequences.Abbreviations COI cytochrome oxidase subunit I - COII cytochrome oxidase subunit II - COIII cytochrome oxidase subunit III - HOS Heme O synthase - ORF open reading frame - SDS sodium dodecyl sulfate     

Postpartum anestrus in French beef cattle: an epidemiological study

Postpartum anestrus of lactating beef cows was studied by means of an epidemiological study carried out on 878 lactating beef cows in 60 French herds. The cows calved between October 1992 and March 1993 and were housed 2 mo after calving, when the anestrus status was determined by progesterone radioimmunoassays. Data analysis was performed using a multiple logistic model in order to adjust for confounding and interaction. Fifty-one percent of the primiparous and 23% of the multiparous cows were found to be in anestrus. Factors significantly related to anestrus were parity (primiparous); breed (Charolais); housing type (tie housing); suckling (compared to weaning at birth); and, among those that were under the control of the farmer, calving conditions (manual exploration of the birth canal); body condition score at calving (3 or less, on a 5-point scale); and loss in body condition score after calving (1 point or more within 2 mo). Previous reproductive performance for multiparous cows such as a long calving interval and induced estrus in the previous year also appeared to be related to anestrus.     

Unmodified and recombinant strains of Lactobacillus plantarum are rapidly lost from the rumen by protozoal predation

A genetically-manipulated strain of Lactobacillus plantarum and the unmodified parent strain were introduced into the rumen of sheep at an initial inoculum level of 1 times 10⁷ cfu ml^-1 of rumen fluid. There were no significant differences between the viable counts of the two inoculants throughout a 24 h sampling period. The rates of loss were 0.36 and 0.29 h^-1 (proportion of colony-forming units lost, measured over the first 2 h) for the parent strain and recombinant strain respectively, and within 24 h of inoculation neither of the strains were detectable in rumen fluid. Further experiments in vitro revealed that the inoculants persisted in sterile rumen fluid with a loss rate of 0.044 and 0.057 h^-1 for the parent strain and the recombinant strain respectively. Incubations with rumen fluid alone, protozoa-free rumen fluid and protozoa-enriched rumen fluid revealed that protozoal predation was the most significant factor in the loss of the introduced population. The loss rates from protozoa-free rumen fluid were not significantly different (P < 0.05) from those observed in sterile rumen fluid.     

Characteristics of Mycoplasma hominis adhesion.

Mycoplasma hominis, a human pathogen, has previously been observed to bind to sulfatide separated on thin-layer chromatograms. It has not been demonstrated, however, that the binding is not simply a nonspecific ionic interaction. The ability of a low-passage patient isolate of M. hominis to adhere to glycoconjugates other than sulfatide and the characteristics of its binding to sulfatide were studied. Mycoplasmas were found to bind strongly and specifically in a temperature- and dose-dependent manner to only sulfatide of all of the glycolipids and glycoproteins tested. The avidity and specificity of binding, as well as the ability to inhibit the interaction specifically, suggest that the receptors to which M. hominis binds, particularly in the human urogenital tract, from which it is frequently isolated, are primarily, if not solely, sulfated glycolipids.     

“Macrophage” nitric oxide synthase is a glucocorticoid-inhibitable primary response gene in 3T3 cells

Both nitric oxide and prostaglandins are potent paracrine mediators of intercellular communication. An endotoxin-lipopolysaccharide (LPS) inducible form of nitric oxide synthase (mac-NOS) has recently been cloned from murine macrophages. An inducible prostaglandin synthase (TIS1O/PGS-2), cloned from 3T3 cells, is also induced in LPS-activated macrophage. Because of the wide range of ligands that induce primary response genes in 3T3 cells, the ease of studying chimeric promoter constructs in 3T3 cells, and the importance of both nitric oxide and prostaglandins as paracrine mediators, we examined expression of mac-NOS in 3T3 cells. Tetradecanoyl phorbol-13 acetate (TPA), forskolin, platelet-derived growth factor, fibroblast growth factor, and serum all induce mac-NOS expression in Swiss 3T3 cells. Thus the mac-NOS gene can respond to a far wider range of inducers than previously suspected. mac-NOS is a primary response gene; cycloheximide does not block induction. TPA-induced mac-NOS and TIS10/PGS-2 mRNA accumulation patterns are similar. LPS is a potent inducer of mac-NOS in Swiss 3T3 cells but cannot induce TIS10/PGS-2. In contrast, v-src expression induces TIS10/PGS-2 message, but not iNOS message in a BALB/c 3T3 cell line containing a temperature-sensitive v-src gene. Dexamethasone (DEX) prevents induction of TIS10/PGS-2, but not most other primary response genes. DEX also blocks mac-NOS induction in Swiss 3T3 cells. The inducible TIS10/PGS-2 and mac-NOS genes, responsible for the production of two distinct paracrine agents, appear to share many regulatory features in 3T3 cells. © 1993 Wiley-Liss, Inc.     

The bovine tubouterine junction: general organization and surface morphology

The bovine tubouterine junction is composed of three parts (terminal tubal segment, transition region proper, uterine apex) and follows a sigmoidal course displaying a tubal and an uterine curvature. In the terminal tubal segment, 4–8 primary longitudinal folds and a system of lower secondary folds, ridges and chords project into the centrally located lumen. The transition region proper possesses a slit-like lumen because of the existence of a thick mucosal pad containing the first uterine glands. The longitudinal primary folds of the tube broaden, flatten and start to diverge when they reach the transition region proper. The mucosal pad and broadened folds are heavily vascularized. A system of lateral outpocketings with blind ends pointing in an ampullary direction develops between the primary and secondary folds, the ridges and chords of the terminal tubal segment and transition region proper. From the bottom of these outpocketings, short tubulo-alveolar crypts originate. The mucosa of the uterine apex forms low transversal ridges. The musculature of the bovine tubouterine junction is divided into a continuous circular or spiral intermediate layer, flanked by inner and outer longitudinal layers. The outer longitudinal layer is incomplete in the terminal tubal segment but increases in thickness to form a continuous stratum in the uterine apex. An inner longitudinal layer occurs only in the terminal tubal segment where it is best developed in the bases of the primary longitudinal folds. The simple columnar surface epithelium of the tubouterine junction contains ciliated and non-ciliated cells. The former undergo cyclical changes, and increase during estrus and postestrus. During proestrus, groups of non-ciliated cells display bulbous apical protrusions. During proestrus and estrus, circumscribed epithelial lesions expose the underlying basal lamina.     

Developmental requirements for the ecdysoneless (ecd) locus in Drosophila melanogaster

The ecdysoneless locus in Drosophila melanogaster has been defined previously by a single conditional mutation, I(3)ecd¹, that causes an ecdysteroid deficit and larval death at the restrictive temperature, 29°C, although the primary role of the mutation in developmental processes has been unclear. Gene dosage and complementation studies reported here for ecd¹ and five nonconditional lethal alleles indicate that the ecd locus plays prezygotic and postzygotic roles essential for normal embryonic development, the successful completion of each larval molt, adult eclosion, and female fertility. The ecd locus is also required for normal macrochaete differentiation. For each observed phenotype, the severity of mutational effects was correlated with ecd mutant genotypes. In all cases, ecd¹ homozygotes were least affected. Mutants heteroallelic for ecd¹ and any one of four nonconditional recessive mutations were more severely affected than ecd¹ homozy-gotes, revealing these as hypomorphic alleles. For all phenotypic effects, mutants heteroallelic for ecd¹ and a dominant mutation (ecd^3D) were most severely affected. These individuals died during embryogenesis at 29°C and developed no macrochaetes on the dorsal thorax when transferred to 29°C during the white prepupal stage. The ecd^3D mutation also caused female semisterility in heterozygotes. Ecdysteroid regulation has been implicated previously in all the developmental processes disrupted by these ecd mutations except for macrochaete differentiation. © 1993 Wiley-Liss, Inc.     

IN VIVO EFFECTS OF CARDIOTROPHIN-1

Cardiotrophin-1 (CT-1) is a recently discovered cytokine that was isolated based on its ability to induce cardiac myocyte hypertrophy in vitro. In this study, the effects of chronic administration of CT-1 to mice (0.5 or 2 μg by intraperitoneal injection, twice a day for 14 days) were determined. A dose-dependent increase in both the heart weight and ventricular weight to body ratios was observed in the treated groups. The body weights of the animals were unaffected. These results indicate that CT-1 can induce cardiac hypertrophy in vivo. CT-1 was not specific for the heart, however. It stimulated the growth of the liver, kidney, and spleen, and caused atrophy of the thymus. CT-1 administration also increased the platelet counts by 70%, with no change in mean platelet volume. Red blood cell counts were increased in the treated animals, and there was a concomitant increase in haemoglobin concentration. Thus, CT-1 has a broad spectrum of biological activities in vivo. This observation is consistent with previous in-vitro findings showing that the mRNA for CT-1 is expressed in several tissues, and that CT-1 can function through binding to the leukaemia inhibitory factor (LIF) receptor and signalling through the gp130 pathway.     

Induction of diapausing amictic eggs in Synchaeta pectinata

Amictic females of a clone of S. pectinata from Star Lake (Norwich, Vermont) may produce diapausing as well as non-diapausing (subitaneous) eggs. The proportion of diapausing eggs produced in cultures was unaffected by temperature (12 vs 19 °C) or rotifer population density (minima of 0.33 vs 3 ind. ml^–1) at 19 °C. However, at 19 °C this proportion was higher in cultures maintained at a low food level suppressing reproduction (5 × 10³ cells ml^–1 Cryptomonas erosa) than in those maintained at a high food level (2 × 10⁴ cells ml^–1); the treatment effect was marginally significant (p=0.067). Consistent with the effect of low food availability, a period of starvation was very effective in inducing the development of diapausing eggs. None of 19 females cultured individually from hatching at 19 °C on C. erosa (2 × 10⁴ cells ml^–1) in 1-ml volumes produced any diapausing eggs in 4 days (0 out of 349 eggs), while 13 out of 16 females subjected to a 15-hour starvation period 6 hours after birth produced one or more diapausing eggs during that time (34% of the 158 eggs produced by the 16 females were diapausing). Diapausing eggs produced and left at 19 °C hatched after 4 to 13 days. Those produced in cultures with a low food level took significantly longer to hatch (9.7 days) than those produced in cultures with a high food level (8.1 days) (p=0.022). In natural communities, S. pectinata should be able to respond directly and rapidly to poor food conditions by producing eggs that undergo an obligatory dormant period before resuming development.