Identification of some lactic acid bacteria from two Zimbabwean fermented milk products

Ten predominant lactic acid bacterial isolates from traditionally fermented milk and four isolates from an industrially fermented milk, Lacto, together with 14 reference strains ofLactobacillus and three ofLactococcus were examined for 32 characteristics. Data were analysed using the simple matching coefficient and clustering was by unweighted pair group average linkage. All the isolated from traditionally fermented milk belonged to the genusLactobacillus. Seven isolates could be identified as belonging toL. helveticus, L. plantarum, L. delbrueckii subsp.lactis, L. casei subsp.casei andL. casel subsp.pseudoplantarum. Three of the isolates could only be identified as either betabacteria or streptobacteria. The four isolates from Lacto were identified asLactococcus lactis. However, they could not be identified to subspecies level.

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Résumé On a examiné 32 caractéristiques de 10 souches de bactéries lactiques isolées de fait fermenté de manière traditionnelle, et de 4 souches isolées d'un lait fermenté industriel, le Lacto, ainsi que 14 souches de référence deLactobacillus et trols deLactococcus. Les données ont été analysées en utilisant le coefficient d'apparienient simple et le groupement par lien moyen de groupe pair non balancé. Toutes les souches isolées du lait fermenté de manfère traditionnelle appartiennent au genteLactobacillus. Sept souches ont pu étre identifiées comme appartenant àL. helveticus, L. plantarum, L. delbruckii subsp.lactis, L. casei subsp.casei etL. casei subsp.pseudoplantarum. Trois de ces souches n'ont pu être identifiées soit comme bétabactéries soit comme streptobactéries. Les quatres souches isolées de Lacto ont été identifiées commeLactococcus lactis. Celles-ci n'ont toutefois pas pu être identifiées jusqu'au stade de sous-espèce.

     

What is Unique About Superoxide Toxicity as Compared to Other Biological Reductants? — A Hypothesis

Usually the toxicity of superoxide is attributed lo its ability to reduce metal ions and subsequently reoxidation of the metal by hydrogen peroxide yields deleterious oxidizing species. As many other nontoxic biological reductants reduce metal compounds, we suggest that part of the mechanism of superoxide toxicity results from its ability to oxidize metal ions bound to biological targets, which subsequently degrade the target via an intramolecular electron Transfer reaction.     

Fruiting at High Temperature and Its Genetic Control in the Basidiomycete Flammulina velutipes

Of 10 geographic strains of Flammulina velutipes, 4 were found capable of fruiting at 22°C (Fr_H) rather than at the typical 15°C (Fr_L). Crosses made between Fr_H and Fr_L monokaryons were never observed to fruit at 22°C. However, some hybrids did fruit at the intermediate temperature of 18°C when grown on appropriate substrates, indicating incomplete dominance of the low-temperature requirement. Analysis of progeny of five Fr_H × Fr_L crosses indicated that a minimum of two genes appears to control the requirement for fruiting at ≤15°C. The genes are not closely linked to either incompatibility locus.     

Actions of LH/hCG on accumulation and catabolism of progestins in cultured rat granulosa cells

Immature hypophysectomized rats were treated with estradiol-17 beta and follicle-stimulating hormone. Granulosa cells were isolated and incubated for 24 h with or without varying doses of ovine luteinizing hormone (NIMADD-oLH-24) or human chorionic gonadotropin (NIADDK CR 125) and accumulations of progesterone and 20 alpha-hydroxy-4-pregnen-3-one were determined. The cells were reincubated for 3 h with [4-14C]progesterone (0.5 nmol/mL) and the radiolabelled metabolites were separated and quantified. Both LH (0.04-1.0 ug/mL) and hCG (0.04-1.0 ug/mL) enhanced the accumulation of endogenous progesterone (by up to 300 and 150%, respectively) and 20 alpha-hydroxy-4-pregnen-3-one (by up to 90 and 85%, respectively) producing dose-dependent increases of the ratio of progesterone to 20 alpha-hydroxy-4-pregnen-3-one (by up to 125 and 70%, respectively). Studies of the metabolism of [1-14C] progesterone have demonstrated that both LH and hCG led to a dose-dependent decrease of the utilization of radiolabelled progesterone (down to 64 and 70%, respectively, of the control value). This effect was associated with an LH- and hCG-dependent inhibition of 20 alpha-hydroxysteroid dehydrogenase activity (down to 60 and 70%, respectively, of the control value) but had no significant effect on 5 alpha-reductase. The present results indicate that LH and hCG stimulate accumulation of progesterone at least in part by decreasing the 20 alpha-hydroxysteroid dehydrogenase activity.     

Effects of prostaglandins E2 and F2 alpha on progesterone metabolism by rat granulosa cells

Rat granulosa cells were cultured with or without PGE2 and/or PGF2 alpha. Accumulation of endogenous progesterone and 20 alpha-hydroxy-4-pregnen-3-one was determined. Additionally, [4-14C]progesterone metabolism was assessed. PGE2 increased progesterone accumulation, in part, by decreasing progesterone catabolism to 20 alpha-reduced progestins. In contrast, PGF2 alpha stimulated 20 alpha-hydroxysteroid dehydrogenase activity, thus increasing progesterone catabolism. Combined treatment with PGE2 and PGF2 alpha augmented progesterone accumulation to levels above controls but below those attained with PGE2 alone. These data indicate that PGE2 and PGF2 alpha exert opposite effects on progesterone production and catabolism and that the ratio of PGE2 to PGF2 alpha in the local granulosa cell milieu may be of importance in determining overall progesterone output.     

Initial stages in the course of adventitious bud formation on embryos of Picea abies

Adventitious buds on embryos of Picea abies (L.) Karst. developed after a pulse treatment with 250 μ M benzyladenine (BA) of pH 5.5 for 2 h. Light and temperature regimes were not critical during the initial stages. Adventitious buds developed faster after a pulse treatment and the variation among different experiments was lower compared to when the embryos were cultured on media supplemented with BA. Various stages of the differentiation of adventitious buds were identified: stage 1 - appearance of meristematic centres (approximately the first two weeks); stage 2 - development of adventitious bud primordia (approximately the third week); stage 3 - adventitious bud development (from approximately the 4th to the 8th week). This system may be used for further studies on bud differentiation.     

Initiation and development of wound tissue and roots on hypocotyl cuttings of Pinus sylvestris in vitro

The rooting of hypocotyl cuttings from 20-day-old seedlings of Pinus sylvestris L. cultured in vitro is discussed. About 40% of the cuttings cultured on medium lacking activated charcoal produced roots during the first two months. When activated charcoal was added to the medium, either root formation (75% formed roots) or wound tissue growth (95% formed large wound tissues) was stimulated in different experiments. These large wound tissues did not develop any roots. The anatomical changes in the basal part of the cuttings were similar during the first two weeks in all the cuttings studied. A vascular cylinder composed of short tracheids with many pores developed. Thereafter the differentiation process became varied. The amount of wound tissue produced and the time for rooting differed among the cuttings. Tracheid nests which were in contact with the vascular system in the hypocotyl via short tracheids were observed after three weeks. Subsequently, roots developed from the tracheid nests. The longer root formation was delayed, the larger the wound tissue became.
Short tracheids were found close to the wound tissue surface. Their ability to adsorb nutrients and water is discussed.     

Transient enhancement of serum somatomedin levels prior to weaning of growth-impaired vasopressin-deficient Brattleboro rats

Somatomedin serum levels of congenitally vasopressin-deficient Brattleboro rats were determined postnatally between day 1 and 55, and compared with heterozygous control values. Assays were performed with a radioimmunoassay of insulin-like growth factor 1 (IGF-1). A transient enhancement of immunoreactive IGF-1 levels between day 8 and 21 of age and a reduction in adulthood was found. This observation shows that the early growth impairments of the Brattleboro mutant are not due to a deficiency of IGF-1.     

Effects of superovulatory doses of pregnant mare serum gonadotropin on oocyte quality and ovulatory and steroid hormone responses in rats

Immature rats (aged 28 days) were injected with 4, 20, or 40 IU pregnant mare serum gonadotropin (PMSG) and sacrificed every 6 or 12 hr. Control rats (4 IU) ovulated between 60 and 72 hr, whereas rats given superovulatory doses of PMSG (20 and 40 IU) ovulated between 24 and 72 hr. The oocyte count from the superovulated rats increased slightly between 24 and 36 hr and markedly between 48 and 72 hr. Degenerated oocytes were recovered 48 and 36 hr after administration of 20 and 40 IU PMSG, respectively. Thereafter, the proportion of degenerated oocytes was dose dependent and reached a maximum at 72 (30.9%, 20 IU) and 60 hr (61.0%, 40 IU). 17β-estradiol content of the superovulated ovaries increased significantly (P < 0.01) from 36 hr and was maximal at 60 (20 IU) or 54 hr (40 IU), when compared to the control regimen. Administration of 40 IU PMSG resulted in a biphasic increase of progesterone content with the peaks at 36 and 60 hr. Androgen content of the superovulated ovaries was lower than control levels during the first 36 hr but was significantly (P < 0.01) higher thereafter. The results suggest that these alterations in the steroid response (particularly androgens) from 36 hr onward following superovulation may be responsible for the coincidental occurrence of abnormal oocytes, possibly by disturbing the specific intrafollicular steroid environment essential for complete maturation. In addition, oocyte aging that is due to earlier activation by the exogenous luteinizing hormone activity may be a contributing factor.     

Antibodies to spiroperidol and their anti-idiotypes as probes for studying dopamine receptors

Spiroperidol was covalently conjugated to bovine serum albumin (BSA). Conjugated spiroperidol was almost as efficient as free spiroperidol in its binding capacity to dopamine receptor. Antibodies to spiroperidol were produced in rabbits following repeated immunizations with the conjugate of spiroperidol and BSA. The obtained antibodies have an apparent K_D of 0.02 nM for [³H]-spiroperidol. These antibodies bind also to other butyrophenones with IC₅₀ values three to four orders of magnitude higher than the IC₅₀ obtained with unlabeled spiroperidol. Antibodies were purified from anti-spiroperidol sera by affinity chromatography. Anti-idiotypic antibodies were raised in rabbits by immunization with the purified anti-spiroperidol antibodies. Some rabbits produced anti-idiotypic antibodies which bind to rat and calf striatum.