Diflubenzuron inhibits reproduction of different strains of Drosophila melanogaster

Abstract  The effect of (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea) insecticide – diflubenzuron – on wild type and white type fruit flies Drosophila melanogaster (Meigen, 1830) was studied. Adult insects were placed in vials with different concentrations of the insecticide in the nutrient (from 0.048 to 48 mg of diflubenzuron per 1 cm³ of the nutrient). In each case, the insects showed some mortality, which was concentration-dependant. When comparing both strains, we could observe different acute toxicities, with wild type being more resistant to diflubenzuron. However, subacute toxicity was similar within both strains. In both strains the prolonged exposure led to the extinction of the majority of the populations (>70%). Although imagoes could freely copulate, we did not observe copulating fruit flies, and we did not find either eggs or larvae in any of the exposed groups. These results indicate that genetic mutation which leads to different eye colour can also affect resistance and survival of insects in pesticide-exposed areas.     

Kinetics of proliferation,cell differentiation,and IgM secretion in the omental lymphoid organ of B10/Sn mice following intraperitoneal immunization with sheep erythrocytes

At different times after single and repeated intraperitoneal injections of SRBC into B10/Sn mice, the [³H]thymidine uptake of omental lymphoid organ (OLO) cells was examined by means of scintillation counting and autoradiographic methods. The specific immune response was assayed by the PFC technique. The first SRBC injection induced, in OLO, proliferative changes in reticulum cells and an intense infiltration with lymphocytes; however, the production of humoral anti-SRBC antibodies was absent. The second immunization provoked the proliferation of lymphoblasts, the appearance of plasmocytes, and the production of specific antibodies of the IgM class only. The results indicate that OLO, thanks to the particular ability of its reticulum cells, presents a microenvironment selectively trapping B lymphocytes and limiting their functional differentiation.     

Waikanae River estuary: Changes to habitat and bird fauna evident from surveys thirty years apart

Abstract

A second ecological survey of the Waikanae estuary, in the North Island of New Zealand, was carried out 30 years after the first (1941–1943), and was of similar duration. The observer for the first survey participated in the second, and the same methods were used. Brief accounts are given of the prevailing climate and geology, and of physical changes at the estuary. The effect of periodic storms and of the various encroachments by man is recorded; the latter appear to be particularly important. The vegetation of the estuary is described. Records of beach patrols and of other ornithologists supplement the authors' observations on the bird life. The numbers of birds recorded in the two surveys are compared by analyses of variance. Changes in the flora deduced from aerial photographs spanning the two surveys and from notes and photographs are related to man-induced disturbance, natural physical changes, and natural succession. The total of 79 bird species recorded at the estuary and in its immediate vicinity compares favourably with the 60 species recorded during the first survey. The increase of nearly one-third is due to such factors as the appearance of new Australian bird species, the information provided by the beach patrols, and the extension of sand-flat habitat. In terms of numbers observed, 10 bird species have increased, 11 remain unchanged, and 8 have declined. The distribution of birds is considered in relation to nine areas of habitat: the beach and open sea; open dunes at the beach front; river and sand flats; unfixed and fixed dunes; saltmarsh; grassed fields; and lakelets. The most species (29) were recorded on sand flats and the least (7) on unfixed dunes. Periodic rechannelling of the river mouth has led to expansion of the sand flats as a habitat for waders and some other shore birds, but other man-induced developments, such as housing, are threatening the present ecological balance of the estuary. Use of the area for recreation and for wildlife study is increasing, and we consider that action by conservation authorities is urgently required.     

Effect of boric acid on antioxidant enzyme activity, lipid peroxidation, and ultrastructure of midgut and fat body of Galleria mellonella

Boric acid is widely used as an insecticide, acaricide, herbicide, and fungicide and also during various industrial processings. Hence, numerous populations are subjects to this toxic compound. Its action on animals is still not fully known and understood. We examined the effect of boric acid on larvae of greater wax moth (Galleria mellonella). The chemical appeared to be toxic for larvae, usually in a concentration-dependent manner. Exposed groups revealed increased lipid peroxidation and altered activity of catalase, superoxide dismutase, glutathione S-transferase, and glutathione peroxidase. We also observed changes of ultrastructure, which were in tune with biochemical assays. We suggest that boric acid has a broad mode of action, which may affect exposed larvae, and even if sublethal, they may lead to disturbances within exposed populations.     

Effects of lead and lead–melatonin exposure on protein and gene expression of metal transporters,proteins and the copper/zinc ratio in rats

Human lead (Pb) exposure induces many adverse health effects, including some related to lead accumulation in organs. Although lead bio-distribution in the body has been described, the molecular mechanism underlying distribution and excretion is not well understood. The transport of essential and toxic metals is principally mediated by proteins. How lead affects the expression of metal transporter proteins in the principal metal excretory organs, i.e., the liver and kidney, is unknown. Considering that co-administration of melatonin and lead reduces the toxic effects of lead and lead levels in the blood in vivo, we examined how lead and co-administration of lead and melatonin affect the gene and protein expression of metal transporter proteins (ZIP8, ZIP14, CTR1 and DMT1) in these organs. Rats were exposed intraperitoneally to lead or lead-melatonin. Our results show that Pb exposure induces changes in the protein and gene expression of ZIP8, ZIP14 and CTR1. Alterations in the copper/zinc ratio found in the blood, liver and kidney were likely related to these changes. With DMT1 expression (gene and protein), a positive correlation was found with lead levels in the kidney. Co-administration of melatonin and lead reduced lead-induced DMT1 expression through an unknown mechanism. This effect of melatonin relates to reduced lead levels in the blood and kidney. The metal transport protein function and our results suggest that DMT1 likely contributes to lead accumulation in organs. These data further elucidate the effects of lead on Cu and Zn and the molecular mechanism underlying lead bio-distribution in animals.     

Biologic effects of microwave exposure. II. Studies on the mechanisms controlling susceptibility to microwave-induced increases in complement receptor-positive spleen cells

In attempting to evaluate the mechanisms responsible for susceptibility to the inductive increase in splenic complement receptor-positive (CR⁺) cells following exposure to 2450-MHz microwaves, it was found that sensitivity to microwave-induced CR⁺cell increases was under genetic control. In particular, evidence was accumulated suggesting that regulation was under the control of a gene or genes closely associated with but outside of the mouse major histocompatibility complex (H-2). All responsive strains of mice tested were of the H-2^k haplotype, while mice of the H-2^a, H-2^b, H-2^d and H-2i⁵ haplotypes were refractory to the microwave-induced increases in CR⁺ cells. By utilizing certain H-2^k strains of mice that were genetically unable to respond to endotoxin, we were able to show that these strains of mice responded to microwaves, but not to endotoxin, by increasing CR⁺ cells. Microwave-induced increases in CR⁺cells were not mimicked by the intraperitoneal injection of hydrocortisone. Athymic mice responded to microwave exposure, indicating that this event was not regulated by the T-cell population. Mice less than eight weeks old were found not to be susceptible to exposure to 2450-MHz microwaves. These studies indicate that microwaves do induce changes in the population of cells with specific cell-surface receptors, that susceptibility to these changes is under genetic control, and that it is unlikely that endotoxin, corticosteroids, or regulatory T cells play a significant role in the mechanisms regulating these increases.     

Simple method to isolate vacuoles and protoplasts for patch-clamp experiments

It was not possible to obtain protoplasts or vacuoles from the thallus of the liverwortConocephalum conicum by applying cell-wall-degrading enzymes. Therefore, a surgical method was developed to isolate protoplasts and vacuoles. A thallus was plasmolyzed and cut. The few protoplasts along the cutting edge that were not destroyed emerged from the edge under deplasmolysis and became thus accessible for a patch pipette. Whereas under slightly hypoosmolar conditions the emerging protoplast remained largely intact, more hypoosmolar conditions gave rise to isolated vacuoles. This method to isolate protoplasts and vacuoles could also be applied to other plant tissues like leaves ofArabidopsis thaliana. Patch-clamp measurements were performed with isolated vacuoles and excised tonoplast patches. A slowly activating vacuolar channel inC. conicum displayed the characteristic features of higher-plant slowly activating vacuolar channels.Abbreviations AP action potential - SV channel slowly activating vacuolar channel     

Ectoparasites from fruit bats and rats on Niue Island

Examination of 3 species of mammals from Niue Island revealed the following host/ectoparasite associations. Rattus rattus (L.) : the mites Androlaelaps casalis, Laelaps echidninus, L. nuttalli, Ornithonyssus bacoti, Listrophoroides cucullatus, and Dermatophagoides pteronys‐sinus; and the louse Polyplax spinulosa. Rattus exulans (Peale) : L. echidninus, L. nuttali, and L. cucullatus; and the louse Hoplopleura pacifica. Pteropus t. tonganus Quoy & Gaimard: the mite Meristaspis calcarata. These new records for the island are discussed in relation to existing records from the Pacific region.