Biosynthesis of RNA polymerase in Escherichia coli

Summary Effect of temperature-sensitive, assembly-defective mutations in Escherichia coli RNA polymerase (rpoB) or subunit gene (rpoC) was investigated on the expression of wild-type rpoB ⁺C⁺operon, which was introduced by infection of a lambda transducing phage drif ⁺ (rpoB ⁺)-6 after UV-irradiation of the mutant cells. In rpoB2·rpoB7 strain which accumulates assembly-intermediates, free , ₂ complex and premature core, the expression of rpoB ⁺C⁺operon measured by the rate of subunit synthesis was considerably inhibited whereas that of EF(translation elongation factor)-Tu, ribosomal proteins L1 and L7/L12, and some -coded proteins remained unaffected. On the other hand, the expression was enhanced specifically for only rpoB ⁺C⁺operon in either rpoC4 or rpoC1 mutants, which are defective in the association of ₂ complex and subunit or the activation of premature core enzyme, respectively. Upon preincubation of the mutant cells at 42° C prior to phage infection, during which assembly intermediates degraded rapidly, the rate of subunit synthesis relative to other phage-corded proteins increased remarkably in rpoB2·rpoB7 mutant as well as in rpoC4 and rpoC1 mutants. These observations strongly suggested the autogenous regulation for at least (rpoB ⁺C⁺) operon by some trans-active diffusible protein complexes built of RNA polymerase subunits. Nature of the regulatory molecules is discussed.Paper VI in this series is Saitoh and Ishihama (1977)     

Analysis of exchanges in differentially stained meiotic chromosomes of Locusta migratoria after BrdU-substitution and FPG staining

The strand relationships of adjacent pairs of chiasmata have been examined in differentially stained meiotic bivalents following in vivo BrdU substitution and FPG staining. A test for chromatid interference is described, based on comparisons of the observed numbers of various combinations of hidden and visible crossover exchanges with the numbers expected assuming no chromatid interference. A comparison based on 67 pairs of chiasmata from Locusta migratoria indicates no evidence for chromatid interference in this material.     

β-glucan degradation in malting sorghum

In all of four malting sorghum varieties, -glucan contents decreased by more than 50% 2 days after germination, due to enzymic digestion. The variety that had the least -glucan content in the malt gave the highest filterable volume of sweet wort while the variety with the highest -glucan content had the lowest volume of filterable wort.A.C. Ogbonna is with the Department of Brewing Science and Technology, University of Uyo, P.M.B. 1017, Uyo, Nigeria, A.L. Egunwu was with the University of Nigeria, Nsukka, Nigeria, and is now with Nigerian Breweries PLC, Aba, Abia State, Nigeria.     

Prey kills predator: Counter-attack success of a spider mite against its specific phytoseiid predator

Success of counter-attack by the spider mite,Schizotetranychus celarius (Banks), against its specific phytoseiid predator,Typhlodromus bambusae Ehara, was examined under experimental conditions. The success of counter-attack by prey females (mothers) against a predaceous larva depended upon the former's density per nest. About 30% of the predaceous larvae were killed when they intruded into a nest containing eight females and their offspring. On the other hand, the prey males (fathers) effectively killed the predators, i.e. one male in the nest killed ca. 40% of the predators while two or three males destroyed up to 80%.The presence of prey parents in a nest considerably enhanced the success of the counter-attack. One male and two young females could kill 70% of the predator's larvae, while two males and two females killed 90% of such larvae. This suggests a kind of cooperative brood defence amongstS. celarius parents.Although more robust, protonymphs of the predator also suffered damage by the prey's counter-attack. However, prey male and female could not destroy the predator's eggs and adult females, whilst the latter often killed spider mite adults.From these as well as previous experiments, it is concluded thatS. celarius has evolved some kind of biparental care for its offspring. It is further proposed that the predator—prey interactions observed in this study provide a unique contribution towards understanding predator—prey coevolution.     

R-bodies inPseudomonas aeruginosa strain 44T1

For the first time R-bodies are described in a new strain 44T1 ofPseudomonas aeruginosa. Its size was measured as being 0.22 to 0.37 m of width per 0.27 to 0.41 m of length and 5 to 9 spiral turns about 16 nm. These structures are similar to previously observed in bacteria and are related with physiological state of bacteria in minimal conditions of growth.     

Distribution and abundance of soft-sediment meiofauna and a predatory goby in a coral reef lagoon

Spatial patterns in the abundance of the softsediment meiofauna and a predatory goby, Valenciennia longipinnis, were examined in the lagoon of One Tree Reef (Great Barrier Reef). The study provided a quantitative framework to assess the importance of physical factors on and predator prey interactions between the meiofauna and V.longipinnis. Patterns of abundance were examined at two spatial scales: among four habitats (100's of m apart) and among sites (10's of m apart) within habitats. Of the four major constituents of the meiofauna (harpacticoid copepods, nematodes, polychaetes and oligochaetes), gut analyses showed that harpacticoid copepods were the primary prey of V.longipinnis. Spatial patterns of meiofaunal abundance in the lagoon were taxon specific. Polychaetes and harpacticoid copepods exhibited significant differences among habitats. Within habitats, however, polychaetes exhibited significant differences between sites whereas copepods were uniformly distributed. Abundances of nematodes and oligochaetes did not differ between habitats. Densities of nematodes differed significantly between sites while the number of oligochaetes were similar at both spatial scales. V.longipinnis was more abundant in shallow habitats than in deep ones. This study suggests that sediment type may be an important factor influencing the distribution of both the goby and the meiofauna. V.longipinnis and two of the four meiofaunal taxa (harpacticoid copepods and polychaetes) were more abundant in the shallow habitat with fine-grained sediments. There was no significant difference between abundances of meiofaunal taxa in sites where V.longipinnis was present or absent. Overall, more fish occurred in the habitat which had the highest densities of harpacticoid copepods.     

A meta-analysis of frontalis EMG levels with biofeedback and alternative procedures

The lack of comparative reviews of the efficacy of EMG frontalis biofeedback versus alternative procedures for reduction of muscle tension prompted the present meta-analytic treatment of literature previously concluded to be equivocal. Twenty studies comparing EMG frontalis biofeedback with other tension-reduction procedures produced a total of 68 separate effect sizes suitable for meta-analysis. Differences between clinical and normal samples were nonsignificant, and data analyses revealed that EMG frontalis biofeedback was significantly superior to control (p<.05) but that alternative forms of muscle relaxation, while effective, did not reach statistical significance.     

Distribution of pectic polysaccharides throughout walls of suspension-cultured carrot cells

Summary A monoclonal antibody (2 F 4) recognizing a conformational epitope of polygalacturonic acid was used for immunogold localization of pectins in walls of suspension-cultured carrot (D. carota L.) cells at the electron microscopic level. In microcolonies of young or mature cells, polygalacturonic acid was essentially located on the middle lamella material expanded at three-way junctions between cells or lining intercellular spaces but was not found in primary walls. Middle lamellae far from junction zones and intercellular spaces were not recognized. Largely esterified pectic polymers, only detected by the 2 F 4 antibodies after on-grid de-esterification treatment by pectin methyl esterases, were present within all primary cell walls. Golgi bodies and associated vesicles were also labeled by the 2 F 4 antibodies only after de-esterification treatment, which indicates that pectic polymers are synthesized and secreted in a highly esterified form. A decrease of pectin esterification, which results probably from an in situ enzymatic de-esterification of the pectic polymers of the primary walls, was observed in senescent cells. These results are discussed in relation to biochemical analyses showing changes of the methyl ester content of pectins during the cell-wall growth.     

Agrobacterium-mediated transformation of apple (Malus x domestica Borkh.): an assessment of factors affecting gene transfer efficiency during early transformation steps

The factors influencing transfer of an intron — containing -glucuronidase gene to apple leaf explants were studied during early steps of an Agrobacterium tumefaciens-mediated transformation procedure. The gene transfer process was evaluated by counting the number of -glucuronidase expressing leaf zones immediately after cocultivation, as well as by counting the number of -glucuronidase expressing calli developing on the explants after 6 weeks of postcultivation in the presence of 50 mg/l kanamycin. Of three different tested disarmed A. tumefaciens strains, EHA101(pEHA101) was the most effective for apple transformation. Cocultivation of leaf explants with A. tumefaciens on a medium with a high cytokinin level was more conducive to gene transfer than cocultivation on media with high auxin concentrations. Precultivation of leaf explants, prior to cocultivation, slightly increased the number of -glucuronidase expressing zones measured immediately after cocultivation, but it drastically decreased the number of transformed calli appearing on the explants 6 weeks after infection. Other factors examined were: Agrobacterium cell density during infection, bacterial growth phase, nature of the carbon source, explant age, and explant genotype.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - CaMV35S 35S RNA of cauliflower mosaic virus - EDTA ethylenediaminetetraacetate - FeNaEDTA ethylenediaminetetraacetate ferric-sodium salt - GusA -glucuronidase - gusA ß-glucuronidase gene of Escherichia coli - gusA-intron ß-glucuronidase gene containing an intron in the coding region - IBA indole butyric acid - 2iP N6-2-isopentenyl adenine - NAA naphthaleneacetic acid - nptII neomycinphosphotransferase II gene - X-Gluc 5-bromo-4-chloro-3-indolyl ß-D-glucuronide     

Inhibitory activities against heterologous α-amylases and in vitro allergenic reactivity of Einkorn wheats

Salt extracts from seeds of 36 lines of Einkorn wheats were analyzed for their inhibitory activity towards two insect (Tenebrio molitor, Coleoptera, and Ephestia kuehniella, Lepidoptera) and one mammalian (human salivary) -amylases. Whereas all ten T. monococcum accessions tested were active towards the lepidopteran enzyme, they had no effect on the coleopteran or the mammalian ones. More variability was found among the 21 lines of T. boeticum analyzed, although none of them inhibited human -amylase. The five accessions of T. urartu showed even greater diversity. Among all Einkorn accessions tested, only two urartu lines affected the three -amylases. These lines displayed inhibition patterns similar to those of T. aestivum and T. turgidum cultivars. Since several breadwheat -amylase inhibitors are major allergens associated with baker's asthma, we also studied the in vitro allergenic activity of salt extracts from the Einkorn wheats under study. No significant differences in IgE-binding were found between these accessions and theT. aestivum or T. turgidum cultivars. Furthermore, putative allergens with molecular sizes in the range of 20–60 kDa were detected in these Einkorn wheats.     

Axillary shoot induction and plant regeneration in Plantago ovata Forssk

Axillary shoot induction and plant regeneration were obtained in Plantago ovata. The optimum medium for inducing axillary shoots was Murashige & Skoog (MS) medium [5] supplemented with 4.6 M kinetin and 0.05 M NAA. Rooting of shoots was best on half-strength MS medium containing 5.0 M IBA and 0.05 M kinetin. The regenerated plants were similar to the control plants in karyotypic and phenotypic details.     

Seasonal Timing and Diel Activity of Lacustrine Brook Charr, Salvelinus Fontinalis, Spawning in a Lake Outlet

The objectives of this study were to determine (1) the seasonal timing and diel activity patterns of lacustrine brook charr when migrating to a lake outlet for spawning, and (2) the homing of reproducing individuals. In 1995, 745 individuals were captured while migrating to the spawning ground compared to 1148 in 1996. In both years, the sex ratio was not significantly different from 1:1 but females were significantly longer than males. The spawning migrations lasted about 48d and were more nocturnal (between 20:00 and 8:00h) than diurnal. The migration to the spawning ground began when water temperature decreased to 13°C and peaked when water temperature decreased from 11°C to 7°C. Peaks in migration activity were always preceded by a sudden decrease followed by an increase in temperature. The spawning migration lasted until the third week of October, when water temperature varied between 3°C and 8°C. Males, especially larger ones, arrived on the spawning ground before females in both years. The length of males migrating to the spawning ground decreased during the spawning season while the females' length showed no pattern. Only 9.7% of the 745 fin-clipped individuals from 1995 returned to the lake outlet to spawn in 1996. The results of this study indicate that lacustrine brook charr show similarities to other anadromous and lake-spawning salmonid populations when migrating to spawning grounds.     

Predator avoidance by the freshwater snailPhysella virgata in response to the crayfishProcambarus simulans

Summary We examined predator avoidance behavior of the freshwater snailPhysella (=Physa) virgata in response to the crayfishProcambarus simulans. In both laboratory and field enclosure experiments snails crawled above the waterline for 2 h or longer, then returned to the water.Physella virgata react to chemical signals given off by crayfish actively foraging on conspecific snails; they do not react to inactive crayfish. Low dissolved oxygen, crowding, and disturbance of the sediments did not elicit crawlout behavior. Crawling above the waterline, by reducing the probability of encounter between vulnerable, thin-shelled snails and crayfish, is an adaptive response to predation.     

Short- and long-term effects of ACTH on the adrenal zona glomerulosa of the rat

Summary Short-term ACTH treatment provoked a decrease in volume of the lipid-droplet compartment in rat zona glomerulosa cells, and a rise in plasma and intracellular concentrations of corticosterone and aldosterone. It enhanced activities of 3-hydroxysteroid dehydrogenase (3HSD), 11-hydroxylase (11OH) and 18-hydroxylase (18OH). Long-term ACTH administration produced a hypertrophy of the zona glomerulosa and its parenchymal cells, a result of the increase in volume of the smooth endoplasmic reticulum and the mitochondrial compartment. The surface area per cell of mitochondrial inner membranes increased; the tubular cristae were transformed into a homogeneous population of vesicles. The plasma and intracellular concentrations of corticosterone further increased, whereas those of aldosterone fell below basal levels (the aldosterone-escape phenomenon). The activities of 3HSD and 11OH were enhanced, that of 180H decreased. Therefore, ACTH stimulates zona glomerulosa growth and transforms parenchymal elements into zona fasciculata celltypes. Cyanoketone nullified acute ACTH effects on plasma and intracellular concentrations of corticosterone and aldosterone, but did not affect the activities of 11OH and 18OH. Chronic ACTH treatment produced similar results, although 18OH activity was not suppressed. The mechanism underlying the aldosterone-escape phenomenon may thus involve a rise in the intracellular concentration of corticosterone, caused by the enhanced synthesis and activation of 3HSD and 11OH.     

Interpretation of metameric architecture in dominant shrubs of the Chilean matorral

Summary The seasonal progression of phenophases in 21 shrub species of the Chilean matorral was analyzed. Five modules or basic units that are responsible for the aboveground architecture of the plants were characterized. These modules appear to be organized in seven different spatial arrangements. In drought-deciduous species a module type with an absolute short shoot with limited apical growth, leafy or spiny, predominated. In evergreen species long shoot and temporal leafy short shoot module types were more frequent. The spatial arrangement of morphologically different modules and the temporal sequence of their formation allow a dynamic interpretation of the modular architecture of the plants.     

Screening Tasmanian marine organisms for antiparasitic activity

Tasmania, the island state of Australia, lies between the latitudes 40° 40S and 43° 40S. For the current study, 455 marine macroorganisms were collected from Tasmanias eastern and south eastern coasts. Organic extracts of these organisms were tested for activity against an endoparasite (nematode) and three ectoparasites (fly, mite and flea); all parasites of significance for domestic animals. The less calcified soft bryozoans (n=23) were an exceptionally rich source of nematocidal extracts, with 35% having high nematocidal activity (LD₉₉ < 250 g/ml). Bryozoans have not previously been identified as sources of nematocidal or, more generally, anthelmintic compounds. The incidence of activity against each of the three test ectoparasites (fly, mite and flea) was similar, overall, with each parasite susceptible to approximately 12% of the extracts. Some 65% of extracts with ectoparasite activity were active against only one ectoparasite. A similar proportion (58%) of extracts with ectoparasite activity had insignificant nematocidal activity. Only six extracts were active against all three ectoparasites. These results indicate a low level of non-specific toxicity across the different parasite classes.     

Thermocyclops ouadanei n. sp. (crustacea: copepoda) from Mauretania (North-West Africa)

Thermocyclops ouadanei n. sp. from Mauretania is described and figured. This new species is characterized by the structure of the receptaculum seminis, the uniting lamella of the P₄ which bears no marginal denticles on the rounded prominences, the length of the apical spines on the endopodite 3 of the P₄ and by the length of the furcal setae. Its relationship with other Thermocyclops species is discussed.Contribution no 16 from project Limnology of the Sahara under contract n° 2.0009.75 with the Fonds voor Kollektief Fundamenteel Onderzoek, Belgium     

17 β-Estradiol Enhances the Outgrowth and Survival of Neocortical Neurons in Culture

Results of this investigation demonstrate that exposure to 17 -estradiol differentially and significantly regulates cortical nerve cell outgrowth depending on the cortical region. Parietal and occipital neurons treated with 1 nM 17 -estradiol showed a greater magnitude of neuronal outgrowth whereas outgrowth of temporal cortex neurons was decreased in the presence of 1 nM 17 -estradiol. Frontal cortex neurons showed a consistent enhancement of neuronal outgrowth that did not reach statistical significance. The dose response profile for 17 -estradiol regulation of the macromorphological features exhibited a bimodal dose response relationship whereas the dose response profile for 17 -estradiol regulation of the micromorphological features exhibited a dose response more characteristic of an inverted V-shaped function. An antagonist to the NMDA receptor antagonist, AP5, abolished the growth promoting effect of 17 -estradiol whereas the nuclear estrogen receptor antagonist ICI 182,780 did not. Lastly, neocortical neurons exposed to 17 -estradiol exhibited greater viability and survival than control neurons over a two week period. These data indicate that 17 -estradiol can enhance the growth and viability of select populations of neocortical neurons and that the growth promoting effects of 17 -estradiol can be blocked by an antagonist to the NMDA glutamate receptor and not by an antagonist to the estrogen nuclear receptor.     

γδ T-cell receptor repertoire in human peripheral blood and thymus

T-cell clones expressing the T-cell receptor (Tcr) were generated from peripheral blood lymphocytes (PBLs) and from a thymus sample. In the panel of ten thymus-derived clones, four Tcr phenotypes [as defined by the reaction of monoclonal antibodies (mAbs) directed against known V and V regions] were identified. All the clones lacked expression of the V3 V region, while seven clones were V1+ . V1 was found in combination with V9 or with undefined VVregions. In addition, two other Tcr phenotypes were identified on these clones: V9⁺ V1^– V3^– and V9^– V1^– V3^– One of the clones expressed CD4 and another was CD8positive. The remaining clones were CD4^– CD8^–. In the panel of 76 PBL-derived, Tcr-bearing clones, five Tcr phenotypes could be identified. In contrast to the thymus-derived clones, 30% of the clones were V3⁺ whereas V1 was expressed by a minority of the clones only. One clone was CD4-positive and approximately 30% of the clones were CD8-positive. Four of the five mAb-defined Tcr phenotypes could be identified on both thymus and PBL-derived T-cell clones. However, biochemical analysis of the Tcrs demonstrates differences in the usage of Ct- and C2-encoded y chains by T cells derived from the thymus and PBLs. The results therefore indicate that, at the clonal level, similarities and differences exist between the Tcr repertoires expressed in the thymus and by PBLs. Furthermore, they indicate that combinatorial Tcr heterogeneity is larger than has so far been described. The receptor diversity, combined with the potential of Tcr+ cells to express CD4 or CD8, indicates that these cells are a heterogeneous population that might mediate a number of immune functions.     

Analysis of primary food sources and trophic relationships of aquatic animals in a mangrove-fringed estuary,Khung Krabaen Bay (Thailand) using dual stable isotope techniques

Stable carbon (¹³C) and nitrogen (¹⁵N) isotopes were used to elucidate primary food sources and trophic relationships of organisms in Khung Krabaen Bay and adjacent offshore waters. The three separate sampling sites were mangroves, inner bay and offshore. The ¹³C values of mangrove leaves were –28.2 to –29.4, seagrass –10.5, macroalgae –14.9 to –18.2, plankton –20.0 to –21.8, benthic detritus –15.1 to –26.3, invertebrates –16.5 to –26.0, and fishes –13.4 to –26.3. The ¹⁵N values of mangrove leaves were 4.3 to 5.7, seagrass 4.3, macroalgae 2.2 to 4.4, plankton 5.7 to 6.4 , benthic detritus 5.1 to 5.3, invertebrates 7.2 to 12.2 , and fishes 6.3 to 15.9. The primary producers had distinct ¹³C values. The ¹³C values of animals collected from mangroves were more negative than those of animals collected far from shore. The primary carbon sources that support food webs clearly depended on location. The contribution of mangroves to food webs was confined only to mangroves, but a mixture of macroalgae and plankton was a major carbon source for organisms in the inner bay area. Offshore organisms clearly derived their carbon through the planktonic food web. The ¹⁵N values of consumers were enriched by 3–4 relative to their diets. The ¹⁵N data suggests that some of aquatic animals had capacity to change their feeding habits according to places and availability of foods and as a result, individuals of the same species could be assigned to different trophic levels at different places.