Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Formation of a barrier by brain microvessel endothelial cells in culture

Endothelial cells (EC) isolated from bovine brain microvessels produce a continuous monolayer when grown in primary culture. The EC are joined together by tight junctions and contain few pinocytotic vesicles. Horseradish peroxidase (HRP) is unable to penetrate this in vitro barrier system. Exposure of the cells to 1.6 M arabinose produces a reversible separation of the tight junctions with penetration of HRP across the monolayer in a pattern similar to that observed in animals after infusion of hyperosmotic solutions into the carotid artery. The behavior of brain microvascular cells in culture suggest that they retain properties important to the formation of the blood-brain barrier.     

The occurrence of the freshwater isopod Heterias (Fritzianira) exul in the Lakes Region of Chile,with notes on the genus Heterias (Asellota: Janiridae)

Heterais exul, previously known from Brazil and Argentina, was collected from a number of lakes and streams in the Lakes Region of Chile (between Valdivia and Puerto Montt). It was found in a wide variety of habitats: on leaf litter, detritus, algae, rotting wood, emergent vegetation, and clean sandy bottoms. Heterias, Pseudasellus, and Fritzianira are placed in synonymy, but Fritzianira is maintained as a subgenus of Heterias because of its lack of an antenna) scale. The 3 Australian species of Heterias and H. exul are believed to have evolved from a common freshwater Gondwanaland ancestor.     

Effect of Hirschmanniella caudacrena on the Submersed Aquatic Plants Ceratophyllum demersum and Hydrilla verticillata

In vitro pathogenicity tests demonstrated that Hirschmanniella caudacrena is pathogenic to Ceratophyllum demersum (coontail). Symptoms were chlorotic tissue, deformed stems, and, finally, death of the plant. Inoculum densities of 500 nematodes per 5-cm-long cutting in a test tube containing 50 ml of water resulted in death and decay of some of the cuttings within 8 weeks; 100 nematodes killed the plants in 12 weeks, and 50 and 25 nematodes killed them in 16 weeks. The lowest inoculum level of 10 nematodes did not seriously affect the plants at 16 weeks when the experiment was terminated. A second test conducted outdoors in glass jars containing 3 liters of water and two cuttings weighing a total of 15 g fresh weight showed damage, but results were not statistically significant. Hydrilla verticillata inoculated with H. caudacrena was not affected seriously.     

Increased accumulation of indole alkaloids by some cell lines of Catharanthus roseus in response to addition of vanadyl sulphate

Vanadyl sulphate (10–500 mg/l), when added to cell suspension cultures of Catharanthus roseus stimulated increased intracellular accumulation of catharanthine and ajmalicine. This response was demonstrated in both flask and fermenter (30 litre) systems. The response varied, and depended upon cell line, concentration of vanadyl sulphate and the stage of the growth phase at which the cells were treated. This process has the potential to increase the yield and reduce the production time for commercially useful secondary plant metabolites.Abbreviations Ajm ajmalicine - Cath catharanthine - CAS ceric ammonium sulphate - VOSO₄ vanadyl sulphate - FW fresh weight - n.d. not detected     

Homozygous paracentric inversion 12 in a mentally retarded boy: a case report and review of the literature

Summary A mentally retarded male was found to be homozygous for a paracentric inversion of the long arm of chromosome 12(inv(12)(q21.1q23.2)). His parents, who are first cousins, and his phenotypically normal younger brother are inversion heterozygotes. Homozygous structural rearrangements are discussed and cases of paracentric inversions, including a further nine previously unpublished, are reviewed.     

The effects of immersion and exercise on prolactin during pregnancy

Prolactin is an important hormone during pregnancy, affecting mother, fetus, and amniotic fluid volume. Immersion is known to affect prolactin levels significantly. To determine the effect of immersion and exercise on the prolactin response during pregnancy, we examined serum prolactin levels at 15, 25, and 35 weeks' gestation and 10 weeks post partum. Twelve women completed 20 min land rest, 20 min immersion in 30 degrees C water to the xiphoid, and 20 min exercise in the water at 60% VO2max. Resting prolactin levels were 1.91 +/- 0.32, 4.55 +/- 0.5, and 5.85 +/- 0.27 nmol.l-1 +/- standard error of the mean at 15, 25, and 35 weeks' gestation, respectively. Postpartum lactating women had a resting mean prolactin level of 3.95 +/- 1.6 versus 0.22 +/- 0.4 nmol.l-1 in non-lactating women. Prolactin levels declined significantly during immersion even after correction for dilution by plasma volume shifts. The immersion response was inversely related to the duration of pregnancy with 29%, 22%, and 12% drops during 15-, 25- and 35-week trials, respectively. Compared to rest, exercise prolactin levels remained depressed during the 15th and 25th week trials. We hypothesize that immersion in water caused prolactin levels to decline.     

Mutations that affect circadian rhythms in Neurospora crassa can alter the reduction of cytochromes by blue light

We have examined membrane fractions from mutant strains of Neurospora crassa that have altered responses to blue light or have altered circadian rhythms. Using an in vitro assay, we assessed whether the mutations affected the levels of photoreducible cytochromes. Three of the mutant strains, prd-1, rib-1, and wc-1, were not qualitatively different from the wild type. The poky strain was found to have high concentrations of photoreducible cytochrome c. After removal of this cytochrome, however, the photoreducible cytochromes in the plasma membrane and endoplasmic reticulum were also similar to those of the wild type. The most significant differences were found in strains mutated at the frq locus, which affects circadian rhythms. In the frq-9 strain, the cytochrome in the endoplasmic reticulum was not detectably reduced by blue light. The frq-1 mutation caused a significant shift in the spectrum of blue-light-reduced cytochrome in the endoplasmic reticulum.     

Antibodies to pollen exines

A polyclonal antiserum and monoclonal antibodies have been prepared to purified pollen exines of Calocedrus decurrens Florin. The location of the antigen is in the exine, as shown by light-and electron-microscopic immunocytochemistry. The greatest reduction in antibody binding follows treatment of the exine with chemicals known to alter sporopollenin. These results provide evidence that sporopollenin is antigenic. Exines of ten species of gymnosperms and angiosperms also bound the polyclonal antiserum, indicating similarity of sporopollenin structure.