Rearing, reproductive behaviour and gamma sterilization of fruit fly, Dacus zonatus (Diptera: Tephritidae)

Investigations were made on rearing, reproductive behaviour and gamma sterilization of one-day old male adults of Dacus zonatus. The larvae were successfully reared on an artificial diet based on wheat shorts. Adult emergence ranged from 89–99% with a sex ratio of about 1:1. Mating occurred at dusk and its duration ranged from 8–13 hours. Males mated a second time with the same female but preferred mating if the already mated female was replaced with a sexually mature virgin female. The optimum dosage for inducing sterility amongst one-day old male adults was 12 kR.

---

Zusammenfassung Zucht und Fortpflanzungsverhalten von Dacus zonatus (Saunders) wurde untersucht. Die Larven wurden vier Generationen lang an einer Diät aus Weizenkleie, Bierhefe, granuliertem Zucker, Agar, Nipagin, Salzsäure und Wasser gehalten. Die Arbeit gibt Daten über Verpuppungsprozentsatz (69,3%), Puppengewicht, Dauer der Ei + Larvenperiode, Schlüpfen der Adulten, Präovipositionszeit, Fruchtbarkeit, Fertilität und Lebensdauer der Adulten. Die Schlüpfrate der Adulten betrug 89–99%, das Geschlechtsverhältnis lag etwa bei 1:1. Die Kopulation findet während der Abenddämmerung statt, sie dauert 8–13 Stunden. Maximum der Kopulationen zwischen dem 10. und 15. Tag nach dem Schlüpfen. Männchen paarten sich ein zweites Mal mit dem gleichen Weibchen, bevorzugten jedoch geschlechtsreife jung-fräuliche Weibchen. Die Eiablage begann am 2.–7. Tag nach der Paarung, die Eizahl betrug bei gepaarten Weibchen 91–564.Die optimale Dosis zur Erzeugung von 99,3% Sterilität bei Bestrahlung von einem Tag alten Männchen war 12 kR. Die Lebensdauer der Bestrahlten war vermindert.

     

Effect of density on age-specific mortality in Drosophila: a density supplementation experiment

Age-specific mortality rates were studied at two adult density levels in four inbred lines of Drosophila melanogaster. In experimental populations, adult densities were maintained at constant levels throughout the experiment by replacing dead flies with live, marked mutants. In control populations, densities declined naturally as the cohorts aged. For all experimental populations the best mortality model is the two-stage Gompertz model, with slower mortality acceleration at older ages. Flies in the experimental populations generally lived longer than flies in control populations, regardless of sex, genotype, or initial density level. The data demonstrate that deceleration of age-specific mortality rates at older ages is not caused by declining cohort densities. Mortality deceleration is a real phenomenon that raises serious questions about the evolution of senescence.     

Influence of drought on competition between selected Rhizobium meliloti strains and naturalized soil rhizobia in alfalfa

Drought is an important environmental factor that can affect rhizobial competition and N₂ fixation. Three alfalfa (Medicago sativa L. and M. falcata L.) accessions were grown in pots containing soil from an irrigated (Soil 1) and a dryland (Soil 2) alfalfa field in northern Utah, USA. Mutants of three strains of Rhizobium meliloti Dang. from Pakistan (UL 136, UL 210, and UL 222) and a commercial rhizobial strain 102F51a were developed with various levels of resistance to streptomycin. Seeds inoculated with these individual streptomycin-resistant mutants were sown in the two soils containing naturalized rhizobial populations. Soils in the pots were maintained at −0.03, −0.5, and −1.0 MPa. After 10 weeks, plants were harvested and nodule isolates were cultured on agar medium with and without streptomycin to determine nodule occupancy (proportion of the nodules occupied by introduced rhizobial strains). Number of nodules, nodule occupancy, total plant dry weight, and shoot N were higher for Soil 1 than Soil 2. Number of nodules, plant dry weight, and shoot N decreased as drought increased from −0.03 to −1.0 MPa in the three alfalfa accessions. Rhizobial strains UL 136 and UL 222 were competitive with naturalized alfalfa rhizobia and were effective at symbiotic N₂ fixation under drought. These results suggest that nodulation, growth, and N₂ fixation in alfalfa can be improved by inoculation with competitive and drought-tolerant rhizobia and may be one economically feasible way to increase alfalfa production in water-limited environments. Joint contribution from USDA-ARS and the Utah Agric. Exp. Sta., Utah State Univ., Logan, UT 84322-4810, USA. Journal Paper No. 4931. Joint contribution from USDA-ARS and the Utah Agric. Exp. Sta., Utah State Univ., Logan, UT 84322-4810, USA. Journal Paper No. 4931.     

Cloning of the Canine GALC cDNA and Identification of the Mutation Causing Globoid Cell Leukodystrophy in West Highland White and Cairn Terriers

Globoid cell leukodystrophy, or Krabbe disease, is a severe, autosomal recessive disorder resulting from a deficiency of galactocerebrosidase (GALC) activity. GALC is responsible for the lysosomal catabolism of certain galactolipids, including galactosylceramide and psychosine. In addition to the human patients, there are several naturally occurring animal models for this disease, including the twitcher mouse, West Highland White terriers (WHWT), and Cairn terriers. All species have deficient GALC activity and have the characteristic pathological findings in the nervous system. We now describe the cloning of the canine GALC cDNA and the identification of the disease-causing mutation in both terrier breeds. The 2007-bp open reading frame is 88% identical to that in human, and the deduced amino acid sequence is about 90% identical. However, the 3′-untranslated region is about 1 kb shorter than that in the human. Two nucleotide changes were found in affected dogs, an A to C transversion at cDNA position 473 (Y158S) and a C to T transition at position 1915 (P639S). Expression studies in COS-1 cells demonstrated that the A to C change at 473 is the disease-causing mutation. A rapid test for the identification of the genotype at that position has been developed, and over 100 WHWT and Cairn terriers have been screened. This will allow breeders to mate their dogs selectively and will permit the establishment of a colony of dogs for use in therapy trials.     

Effects of predatory risk and resource renewal on the timing of foraging activity in a gerbil community

The foraging decisions of animals are often influenced by risk of predation and by the renewal of resources. For example, seed-eating gerbils on sand dunes in the Negev Desert of Israel prefer to forage in the bush microhabitat and during darker hours due to risk of predation. Also, daily renewal of seed resource patches and timing of nightly foraging activity in a depleting environment play important roles in species coexistence. We examined how these factors influence the timing of gerbil foraging by quantifying foraging activity in seed resource patches that we experimentally renewed hourly during the night. As in previous work, gerbils showed strong preference for the safe bush microhabitat and foraged less in response to high levels of illumination from natural moon light and from artificial sources. We demonstrate here for the first time that gerbils also responded to temporal and spatial heterogeneity in predatory risk through their timing of activity over the course of each night. Typically, gerbils concentrated their activity early in the night, but this changed with moon phase and in response to added illumination. These results can be understood in terms of the nature of patch exploitation by gerbils and the role played by the marginal value of energy in determining the cost of predation. They further show the dynamic nature of gerbil foraging decisions, with animals altering foraging efforts in response to time, microhabital, moon phase, illumination, and resource availability.     

Anatomy of the stimulative sequences flanking the ARS consensus sequence of chromosome VI in Saccharomyces cerevisiae

We have analyzed the relationship between autonomously replicating sequence (ARS) structure and function for three ARS (ARS605, ARS607 and ARS609) from chromosome VI of Saccharomyces cerevisiae by systematic XhoI-linker mutation in the ARS consensus sequence (ACS) and flanking sequences. All mutations that encroached upon the ACS destroyed ARS activity. DNA sequences stimulative for ARS function were identified on either side of the ACS of ARS605 and only on the 3'-side of the ACS of ARS607. In ARS609, however, no such stimulative sequences were observed. Base substitutions complementary to the wild-type sequence of those stimulative regions, in ARS605 and ARS607, that did not change the AG of unwinding nor affected ARS activity suggests that these regions have, at least, a function as DNA-unwinding elements (DUE). ARS605, ARS607 and ARS609 DNA are of low AG value and showed hypersensitivity to single-strand-specific nuclease when inserted in negatively supercoiled plasmid. Linker mutations inhibitory for ARS activity (5L11 and 7L14) also caused significant changes in local nucleotide (nt) sensitivity within the ACS and its adjoining regions. Complementary base substitutions, however, did not affect these changes in local nt sensitivity. These results imply that the stimulative regions flanking the ACS are necessary to produce an optimum conformation around the ACS which may be important for full ARS activity.     

Does Gγ/Aγ ratio and Hb F level influence the severity of sickle cell anaemia

Sickle cell anaemia (SCA) exhibits significant variations in clinical presentation in different populations for which several genetic factors including SCA-associated -and -thalassaemias, G-6-PD deficiency and elevated Hb F level have been implicated as possible ameliorating factors. Saudi Arabia is unique in that mild and severe forms of the disease occur at a high frequency. We investigated the G/A ratio and Hb F level and correlated these values with the severity of SCA. The results showed that Hb F level varies significantly in both groups of patients with no evident correlation with the mild clinical manifestations. However, G/A ratio correlated significantly with the disease severity where a high ratio was observed in patients with the mild and a low ratio in patients with the severe disease. The results are evaluated and discussed in the light of correlation studies and regression analysis.     

Flow injection assays for NADH and ethanol using photosensitized rose bengal and luminol–copper (II) chemiluminescence system

The online photoreaction of the rose bengal photosensitized luminol–copper (II) chemiluminescence (CL) system was used for the determination of β-nicotinamide adenine dinucleotide (NADH) and ethanol (EtOH) in pharmaceutical formulations combined with a flow injection technique. NADH can significantly enhance the CL emission of the reaction. For EtOH, alcohol dehydrogenase in soluble form was utilized in the presence of nicotinamide adenine dinucleotide resulting in NADH production. The limit of detection (3σ blank, 𝑛 = 3) of 4.0 × 10⁻⁸ and 2.17 × 10⁻⁵ M, and linear range 1.3 × 10⁻⁷ to 2.5 × 10⁻⁵ M (R² = 0.9998, n = 6) and 0.11–2.17 × 10⁻³ M (R² = 0.9996, n = 6) were obtained for NADH and EtOH respectively. The injection rate was 100 h⁻¹ with a relative standard deviation (n = 3) of 1.5–4.8% in the range studied for both analytes. The procedure was satisfactorily applied to pharmaceutical formulations with recoveries in the range 91.6 ± 3.0% to 110 ± 2.0% for NADH and 88 ± 3.0% to 95.4 ± 4.0% for EtOH. The results obtained were very consistent and did not differ considerably from the reported approaches at a 95% confidence limit. The possible mechanism of the CL reaction is also explained briefly.     

Integrating sample similarities into latent class analysis: a tree-structured shrinkage approach

This paper is concerned with using multivariate binary observations to estimate the probabilities of unobserved classes with scientific meanings. We focus on the setting where additional information about sample similarities is available and represented by a rooted weighted tree. Every leaf in the given tree contains multiple samples. Shorter distances over the tree between the leaves indicate a priori higher similarity in class probability vectors. We propose a novel data integrative extension to classical latent class models with tree-structured shrinkage. The proposed approach enables (1) borrowing of information across leaves, (2) estimating data-driven leaf groups with distinct vectors of class probabilities, and (3) individual-level probabilistic class assignment given the observed multivariate binary measurements. We derive and implement a scalable posterior inference algorithm in a variational Bayes framework. Extensive simulations show more accurate estimation of class probabilities than alternatives that suboptimally use the additional sample similarity information. A zoonotic infectious disease application is used to illustrate the proposed approach. The paper concludes by a brief discussion on model limitations and extensions.