The effect of camphor on bacterial bioluminescence

Summary The inhibitory effect of camphor on bioluminescence of both bacteria and bacterial luciferase has been examined. The camphor has been shown to be a substrate of cytochrome P-450 of the luminous bacteria Photobacterium fischeri. The inhibition of the luminescence reaction provided evidence for the competitive nature of the interaction of camphor and aliphatic aldehyde at the binding site for luciferase. Camphor is also supposed to interact with P-450. The findings indicate that the hydroxylation process of camphor affects the kinetics of the luminescence.     

Seasonal changes in the testes of a hill stream teleost, Garra gotyla (Gray)

The cephalic, middle and posterior regions of the testes in Garra gotyla are identical in structure and function. The spermatogenetic activity starts in the month of October reaching its peak in April and May. Spawning takes place in June and July followed by a brief resting period. Spermiation appears to be intermittent. Six stages of spermatogenesis have been described. New crop of germ cells appears to arise from the resting spermatogonia. Both the interstitial and the lobule boundary cells were observed. The gonosomatic index shows correlatation between the rise in water temperature and the volume of the testes.     

Histology and seasonal changes in the testes of a hill-stream fish Schizothorax plagiostomus.

Histology and annual cyclic changes in the testicular activity of S. plagiostomus have been described. The reproductive cycle has been divided into eight phases. The weight and volume of the testes and GSI show correlation with each other, and increase twice in a year (September and March), indicating the existence of two spawning periods. A distinct dormant period during winter intervenes the spawning peaks. Although the testes contain mature spermatozoa during winter, spermiation remains halted until last week of February. On the return of favourable environmental conditions in March, spermiation begins again and complete depletion takes place.     

Aldolases of the lactic acid bacteria

Reciprocal qualitative and quantitative immunological experiments employing an anti-Pediococcus cerevisiae aldolase serum confirmed many of the interspecific relationships demonstrated previously among lactic acid bacteria with antisera prepared against the Streptococcus faecalis fructose diphosphate aldolase. The extent of immunological relatedness observed between the Lactobacillus and Pediococcus aldolases was markedly greater than that noted between Pediococcus and Streptococcus aldolases indicating that the pediococci share closer phylogenetic ties with the rod-shaped lactobacilli than with their spherical counterparts in the streptococci. In addition to confirming the existence of definitive, but distant, relationships between the lactic acid bacteria and certain gram positive nonsporeforming anaerobes, immunological cross-reactivity was also demonstrated between the pediococcal aldolases and those of Aerococcus viridans.This paper is dedicated with deepest appreciation to Prof. Roger Y. Stanier on the occasion of his 60th birthday in token of what his friendship and guidance have meant to me. — J. L.     

Effect of chronic intake of ethanol on lactate/pyruvate and beta-hydroxybutyrate/acetoacetate ratios in rat liver.

Adult male rats were fed a liquid diet providing 35% of the calories as ethanol, while pair-fed controls received the corresponding diet with alcohol replaced by an equicaloric concentration of sucrose. After 1 month, lactate/pyruvate (L/P) and beta-hydroxybutyrate/acetoacetate (beta-HB/AcAc) ratios in the livers were determined under five different conditions: (1) both diets present up to the time of sacrifice, (2) ethanol diet replaced by control diet for 24 h before sacrifice, (3) ethanol diet replaced by control diet for 48 h before sacrifice, (4) as in the preceding, followed by intraperitoneal (i.p.) injection of ethanol, 1 g/kg, 1 h before sacrifice, (5) as in the preceding, but i.p. injection 3 h before sacrifice. The L/P ratio was significantly higher in the alcohol group than in controls under the first experimental condition, but the groups did not differ under the other four conditions. The beta-HB/AcAc ratio was also significantly higher in the alcohol group under the first condition. This difference disappeared in the second and third conditions. Under the fourth and fifth conditions the beta-HB/AcAc ratio was significantly higher in the controls. The results are compatible with an adaptive increase in mitochondrial reoxidation of NADH in the chronic alcohol groups, but the possibility of a change due to alcohol withdrawal can not be excluded.     

Cycloheximide resistance in Chinese hamster cells. II. Induction of Chm resistance in Chinese hamster cells by N-nitrosomethylurea.

Mutant Chinese hamster ovarian (CHO) cells with a resistance to 7-10(-7) and 8-10(-7) M cycloheximide (CHM) were induced at mutation rates of 1.9-5.2-10(-3) and 1.6-1.8-10(-3) respectively after treatment with N-nitrosomethylurea (NMU) at 100 mug/ml. The induced mutation rates differed by two orders of magnitude from the spontaneous rate of mutation to CHM resistance.     

Effect of streptozotocin on the blood glucose level and histology of the principal islets of Channa punctatus (Bloch).

The effect of streptozotocin, an antibiotic and diabetogenic drug, has been studied on the blood glucose level and islet histology of a freshwater fish, Channa punctatus. The drug elicits a triphasic response in the blood glucose level, comprising an initial hyperglycemia followed by a transient fall, and restitution of normal values 3...4 days after the treatment. Significant degenerative changes occur in the islet beta cells. Severity of the beta cell damage is dose dependent and the drug has been found to be beta-cytotoxic to a considerable extent. Unlike mammals, Channa punctatus does not become diabetic following the streptozotocin administration, at doses varying 200-400 mg/kg b.wqnd over a period of 96 hours post-injection.     

Fusing VE-Cadherin to α-Catenin Impairs Fetal Liver Hematopoiesis and Lymph but Not Blood Vessel Formation

We have recently shown that genetic replacement of VE-cadherin by a VE-cadherin–α-catenin fusion construct strongly impairs opening of endothelial cell contacts during leukocyte extravasation and induction of vascular permeability in adult mice. Here we show that this mutation leads to lethality at midgestation on a clean C57BL/6 background. Investigating the reasons for embryonic lethality, we observed a lack of fetal liver hematopoiesis and severe lymphedema but no detectable defects in blood vessel formation and remodeling. As for the hematopoiesis defect, VE-cadherin–α-catenin affected neither the generation of hematopoietic stem and progenitor cells (HSPCs) from hemogenic endothelium nor their differentiation into multiple hematopoietic lineages. Instead, HSPCs accumulated in the fetal circulation, suggesting that their entry into the fetal liver was blocked. Edema formation was caused by disturbed lymphatic vessel development. Lymphatic progenitor cells of VE-cadherin–α-catenin-expressing embryos were able to leave the cardinal vein and migrate to the site of the first lymphatic vessel formation, yet subsequently, these cells failed to form large lumenized lymphatic vessels. Thus, stabilizing endothelial cell contacts by a covalent link between VE-cadherin and α-catenin affects recruitment of hematopoietic progenitors into the fetal liver and the development of lymph but not blood vessels.     

A diverse uncultivated microbial community is responsible for organic matter degradation in the Black Sea sulphidic zone

Organic matter degradation in marine environments is essential for the recycling of nutrients, especially under conditions of anoxia where organic matter tends to accumulate. However, little is known about the diversity of the microbial communities responsible for the mineralization of organic matter in the absence of oxygen, as well as the factors controlling their activities. Here, we determined the active heterotrophic prokaryotic community in the sulphidic water column of the Black Sea, an ideal model system, where a tight coupling between carbon, nitrogen and sulphur cycles is expected. Active microorganisms degrading both dissolved organic matter (DOM) and protein extracts were determined using quantitative DNA stable isotope probing incubation experiments. These results were compared with the metabolic potential of metagenome-assembled genomes obtained from the water column. Organic matter incubations showed that groups like Cloacimonetes and Marinimicrobia are generalists degrading DOM. Based on metagenomic profiles the degradation proceeds in a potential interaction with members of the Deltaproteobacteria and Chloroflexi Dehalococcoidia. On the other hand, microbes with small genomes like the bacterial phyla Parcubacteria, Omnitrophica and of the archaeal phylum Woesearchaeota, were the most active, especially in protein-amended incubations, revealing the potential advantage of streamlined microorganisms in highly reduced conditions.     

Gut-associated immune effector responses in immunocompetent and immunocomprimised mice with Giardia lamblia

Abstract Significantly higher Giardia lamblia trophozoites load in the intestine of infected mice accompanied pronounced influx of suppressor/cytotoxic T cells (Lyt 2.2⁺), T cells (Thy 1.2⁺) and significant reduction in IgA-containing cells in the gut during the establishment and peak phases of infection. The induction of helper/inducer T cells (Lyt 1.1⁺) and significant enhancement of IgA-containing cells in gut resulted in the decline of the trophozoite loads. However, the prior treatment of animals with dexamethasone alone resulted in significant reduction in helper/inducer T cells (Lyt 1.1⁺) and the IgA-containing cells in the gut; the percents of suppressor/cytotoxic T cells (Lyt 2.2⁺) and IgM-containing cells remained unaltered. Although the G. lamblia infection in such animals further significantly increased the influx of suppressor/cytotoxic T cells, the late response of helper/inducer T cells and IgA-containing cells was abrogated during the decline phase of infection. The significant reduction in the trophozoite load — despite immuno-suppressive therapy — appeared to be due to unaltered IgM response in such animals which probably took over the function of IgA in defense against G. lamblia . The data of the investigation thus suggested a role of helper/inducer T cells and antibodies producing cells in gut as important effector cells resulting in the termination of primary G. lamblia infection.