Pathogenesis of reproductive failure induced by Trypanosoma vivax in experimentally infected pregnant ewes

The present study was aimed at investigating the effect of experimental infection by Trypanosoma vivax in different stages of pregnancy, determining the pathogenesis of reproductive failure, and confirming transplacental transmission. We used 12 pregnant ewes distributed into four experimental groups: G1, was formed by three ewes infected with T. vivax in the first third of pregnancy (30 days); G2 comprised three infected ewes in the final third of pregnancy (100 days); G3 and G4 were composed of three non-infected ewes with the same gestational period, respectively. Each ewe of G1 and G2 was inoculated with 1.25 × 10⁵ tripomastigotes. Clinical examination, determination of parasitemia, serum biochemistry (albumin, total protein, glucose, cholesterol, and urea), packed cell volume (PCV), serum progesterone, and pathological examination were performed. Placenta, amniotic fluid, blood and tissues from the fetuses and stillbirths were submitted to PCR. Two ewes of G1 (Ewe 1 and 3) presented severe infection and died in the 34^th and 35^th days post-infection (dpi), respectively; but both fetuses were recovered during necropsy. In G2, Ewe 5 aborted two fetuses on the 130^th day (30 dpi) of pregnancy; and Ewe 6 aborted one fetus in the 140^th day (40 dpi) of gestation. Ewes 2 and 4 delivered two weak lambs that died five days after birth. Factors possibly involved with the reproductive failure included high parasitemia, fever, low PCV, body score, serum glucose, total protein, cholesterol, and progesterone. Hepatitis, pericarditis, and encephalitis were observed in the aborted fetuses. The presence of T. vivax DNA in the placenta, amniotic fluid, blood, and tissues from the fetuses confirms the transplacental transmission of the parasite. Histological lesion in the fetuses and placenta also suggest the involvement of the parasite in the etiopathogenesis of reproductive failure in ewes.     

The response of pyriproxyfen-resistant and susceptible Bemisia tabaci Genn (Homoptera: Aleyrodidae) to pyriproxyfen and fenoxycarb alone and in combination with piperonyl butoxide

Pyriproxyfen was effective against susceptible Bemisia tabaci eggs at a LC₅₀ of 0.003 mg litre⁻¹ and against nymphs at 0.02 mg litre⁻¹. In comparison, eggs of a laboratory selected, pyriproxyfen-resistant B tabaci strain, originating in an Israeli greenhouse, exhibited 6500-fold resistance and nymphs exhibited 1100-fold resistance. Eggs and nymphs of a strain from an Israeli sunflower field exhibited 450 and 210-fold resistance in comparison to the susceptible standard. Fenoxycarb was generally less effective than pyriproxyfen against B tabaci eggs and nymphs but was unaffected by pyriproxyfen resistance. Piperonyl butoxide (PB) was antagonistic to pyriproxyfen, and this increased with increasing pyriproxyfen resistance. PB had no effect on the toxicity of fenoxycarb. Collectively, these data imply that the modes of action of pyriproxyfen and fenoxycarb are distinct, despite the structural similarities of these molecules. Possible reasons for the antagonism of PB against pyriproxyfen are discussed. © 1999 Society of Chemical Industry     

Sudden death of a bearded vulture (Gypaetus barbatus) possibly caused by Newcastle disease virus

An adult female bearded vulture (Gypaetus barbatus) in the Tel Aviv University Research Zoo was found dead without previous clinical signs. The predominant pathologic changes were considerable bloody content in the intestines and enlargement of the liver, which had a rubbery consistency with color changes. Microscopic lesions consisted of multifocal histiocytic infiltration in the liver. Newcastle disease virus (NDV) was isolated from a cloacal swab and from the lungs and liver. Intracerebral pathogenicity index of the virus, as estimated in 1-day-old chicks, was repeated three times and had an average value of 1.68, indicating a velogenic strain. Numerous Clostridium septicum bacteria were found on the intestinal surface, but bioassays in which they were orally administered into chickens and mice revealed that, even though they were heavily multiplied in the intestines, they were nonpathogenic. It seems that NDV, documented for the first time in a bearded vulture in Israel, was the likely cause of sudden death.     

The newest leafminer pest in Israel,Liriomyza huidobrensis

The pea leafminer,Liriomyza huidobrensis (Blanchard), recently introduced into Israel, has proven to be extremely proliferous and difficult to control. It is a much more serious pest of vegetable and flower crops than the previously introducedLiriomyza trifolii (Burgess). Photosynthesis is reduced and cosmetic damage is incurred when adult flies stipple plant leaves with feeding punctures and larvae mine the leaves. This paper will review briefly the history, biology and potential control measures of the pea leafminer.     

Emamectin,a novel insecticide for controlling field crop pests

Emamectin is a macrocyclic lactone insecticide with low toxicity to non-target organisms and the environment, and is considered an important component in pest-management programmes for controlling field crop pests. It is a powerful compound for controlling the cotton bollworm Helicoverpa armigera (Hübner). A spray concentration of 25 mg AI litre-1 in a cotton field resulted in over 90% suppression of H armigera larvae up to day 28 after treatment, while similar mortality of the Egyptian cotton leafworm Spodoptera littoralis Boisduval, under the same conditions, was maintained for 3 days only. Emamectin is a potent compound for controlling the western flower thrips Frankliniella occidentalis (Pergande) under both laboratory and field conditions and its activity on adults was over 10-fold greater than that of abamectin. Spray concentrations of 10 and 50 mg AI litre-1 in Ageratum houstonianum Mill flowers resulted in total suppression of adults up to day 11 and of larvae up to day 20 after treatment. Under standard laboratory conditions, emamectin exhibits a considerable activity on the whitefly Bemisia tabaci (Gennadius) and the leafminer Liriomyza huidobrensis (Blanchard). Further studies are required to evaluate its potential activity on the latter pests under field conditions.     

Tonometry in three herbivorous wildlife species

Tonometry was performed to estimate intraocular pressure (IOP) in 12 Nubian ibexes ( Capra ibex nubiana ), 10 Grant zebras ( Equus burchelli  ) and five Arabian oryxes ( Oryx leucoryx ), using both applanation (Tono-Pen) and/or indentation (Schiotz) tonometers. Animals were anesthetized with a mixture of etorphine hydrochloride and acepromazine maleate. Mean (± SD) IOP in the ibex was 17.95 ± 4.78 mmHg (24 eyes, indentation tonometry). In the zebra, indentation tonometry (20 eyes) yielded a mean IOP of 25.30 ± 3.06 mmHg, and applanation tonometry (six eyes) yielded a mean IOP of 29.47 ± 3.43 mmHg. In the oryx, indentation tonometry (five eyes) yielded a mean IOP of 22.68 ± 8.15 mmHg, and applanation tonometry (10 eyes) yielded a mean IOP of 11.76 ± 3.43 mmHg. There were no significant effects of gender, age, weight, side or reading number on the IOP measured in any of the three species. No significant differences were found between the IOP of the three species, nor between the readings of the two instruments, although some of the P -values were close to the significance level.     

A case-control study to identify farm factors affecting fertility of dairy herds: univariate description of factors

Objective To identify farm factors which were associated with reproductive performance in dairy herds in New South Wales.
Procedure A survey was administered by face to face interview to examine the responses of producers drawn from 757 herds, which used the New South Wales Agriculture Department Dairy Herd Improvement scheme. A case-control approach was used to select a total of 126 herds from the first (top group - cases) and fourth quartiles (low group - controls) for intercalving interval.
Results We found that the estimated interval from calving to first mating was significantly different between groups (P = 0.03) and that the groups significantly differed in both their target for interval to first mating (P = 0.02) and their perceived optimum time for first mating (P = 0.04). Other factors associated with a longer intercalving interval included, use of embryo transfer programs (P = 0.08), younger managers (P = 0.02), fewer breedings per day (P = 0.01), a greater number of people detecting heats (P = 0.07), but less hours spent detecting heats while handling the cows (P = 0.11), and a failure to vaccinate bulls for campylobacteriosis (P = 0.14).
Conclusions Managers of herds with poorer reproductive performance did not intend to mate cattle as soon after calving as managers with better reproductive performance, were not as active in seeking veterinary advice on reproduction, and were attempting to treat reproductive diseases and disorders themselves.     

The viking biological investigation: preliminary results

Three different types of biological experiments on samples of martian surface material ("soil") were conducted inside the Viking lander. In the carbon assimilation or pyrolytic release experiment, (14)CO(2) and (14)CO were exposed to soil in the presence of light. A small amount of gas was found to be converted into organic material. Heat treatment of a duplicate sample prevented such conversion. In the gas exchange experiment, soil was first humidified (exposed to water vapor) for 6 sols and then wet with a complex aqueous solution of metabolites. The gas above the soil was monitored by gas chromatography. A substantial amount of O(2) was detected in the first chromatogram taken 2.8 hours after humidification. Subsequent analyses revealed that significant increases in CO(2) and only small changes in N(2) had also occurred. In the labeled release experiment, soil was moistened with a solution containing several (14)C-labeled organic compounds. A substantial evolution of radioactive gas was registered but did not occur with a duplicate heat-treated sample. Alternative chemical and biological interpretations are possible for these preliminary data. The experiments are still in process, and these results so far do not allow a decision regarding the existence of life on the plonet Mars.     

Planetary contamination I: the problem and the agreements

The sterility requirements for landed spacecraft tentatively adopted in the COSPAR resolution of 1964 are so severe as to pose a major obstacle to planetary exploration. This by itself would not justify modification of the re quirements, since preservation of the biological integrity of Mars is essential for proper exploration of the planet. However, when the physical and biological assumptions underlying the COSPAR recommendations are com pared with actual conditions on Mars, as established by recent observations, it becomes apparent that the COSPAR as sumptions are unrealistic in important respects. Specifically, the belief that eolian erosion on Mars can effect the release of spores trapped in the interior of solids in periods of time that are short compared with the time scale of the unmanned space program is unsup ported by either observation or theory. On the contrary, the analysis suggests that rates of eolian erosion on Mars are very low. Similarly, present knowledge of the Martian environment opposes the view that terrestrial microorganisms would readily contaminate the planet. The combination of dryness, lack of oxygen, and high ultraviolet flux makes the surface of Mars peculiarly unsuit able for the multiplication of terrestrial organisms. Recent studies give little sup port to the proposal that significant areas of geothermal activity exist on Mars. These various findings suggest that the COSPAR-recommended constraints could be substantially relaxed without compromising to any significant degree the biological condition of Mars. In particular, a distinction needs to be made between microorganisms trapped in solids and those on exposed sur faces of landed spacecraft. Surface sterility is an unconditional require ment, in the sense that it is imposed by considerations unrelated to the nature of the Martian environment. Sterilization of the interior of solids to the extreme level recommended by COSPAR, however, is based on the as sumption that entrapped organisms con stitute a substantial hazard to the ecology of Mars. This assumption now seems unjustified, and the need for a high degree of interior sterility is doubt ful. Current spacecraft-sterilization pol icies should be revised accordingly.