Abundance of Lutzomyia ovallesi but not Lu. gomezi (Diptera: Psychodidae) correlated with cutaneous leishmaniasis incidence in north-central Venezuela

In north-central Venezuela Lutzomyia gomezi and Lu. ovallesi are the main endophilic/anthropophilic species of phlebotomine sandflies implicated as vectors of cutaneous leishmaniasis (CL). Lutzomyia ovallesi has been found infected with Leishmania braziliensis (1.2%) and less often with Le. mexicana (0.07%), while Le. braziliensis infections have also been found in Lu. gomezi (0.47%). We investigated population densities of these sandflies using two sampling methods with four series of collections between January 1991 and March 1995 at El Ingenio, Miranda State. All-night outdoor collections from a Shannon trap were correlated with indoor collections from CDC light–traps by linear regression, which proved to be statistically significant for both species. Estimated numbers of female sandflies per house per night were found to be proportional to monthly precipitation (i.e. rainfall), with a lag time of seven months for Lu. ovallesi and of six months for Lu. gomezi . Predominance of Lu. ovallesi over Lu. gomezi ( c. 10 :1 ) was observed throughout the year, with the number of infected females estimated as 0.043 ± 0.047 Lu. ovallesi and 0.0085 ± 0.0124 Lu. gomezi per CDC trap per house per night (ratio ∼ 5:1). The mean rate of new CL cases per house per year and sandfly abundance were correlated by linear regression, showing a statistically significant relationship for Lu. ovallesi but not for Lu. gomezi . The negative intercept indicated that, on average, the CDC trap density exceeds 800 Lu. ovallesi females/house/year before new CL cases occur at El Ingenio.     

Teratoid Tumors Derived from Mouse Embryos Grown in an Immunologically Privileged Site

Mouse early embryos and embryo fragments were transplanted into an immunologically privileged site, consisting of a glass cylinder previously implanted under the skin of adult mice in order to test their tumor producing potential, in allogeneic adult recipients. The highest yield of tumors was obtained upon transplantation of 6 1/2 day old embryos in toto. i.e., including the embryonic and extraembryonic areas. Histological examination showed teratomas composed of differentiated tissues derived from the three germ layers containing isolated foci of undifferentiated cells and nodules of trophoblast giant cells. Areas exhibiting the histological appearance of yolk sac carcinoma were also observed. Transplantation of the whole 6 1/2 day old egg cylinder, including the ectoplacental cone, and the isolated embryonic area produced a lower incidence of teratomas with a reduced variety of differentiated tissues. No yolk sac carcinoma was found in these grafts. The ectoplacental cone of 6 1/2 day embryos produced no tumors. Grafts of genital ridges from 12 1/2 day embryos gave rise to teratomas with well differentiated tissues of embryonic and extraembryonic origin. Areas ressembling yolk sac carcinoma were also observed. The life span of trophoblastic giant cells within the glass cylinder was significantly longer than in other experimental systems.     

The phlebotomine sandflies of Venezuelan Amazonia

Phlebotomine sandflies were surveyed in two ecologically contrasted areas, the northern moist and southern wet tropical forests, of the Territorio Federal Amazonas, Venezuela. Three new taxa and twenty-one new records were added to the previously known species list for Venezuelan sandflies, which now totals eighty species. Both sexes of Lutzomyia (Psychodopygus) killicki sp.n., L. (Trichophoryomyia) bettinii sp.n., L. (Nyssomyia) olmeca reducta subsp.n. and and the females of L. bernalei Osorno et al., Brumptomyia pintoi Costa Lima and L. begonae (Ortiz & Torres) are described and illustrated.     

Xenobiotic-induced apoptosis: significance and potential application as a general biomarker of response

The process of apoptosis, often coined programmed cell death, involves cell injury induced by a variety of stimuli including xenobiotics and is morphologically, biochemically, and physiologically distinct from necrosis. Apoptotic death is characterized by cellular changes such as cytoplasm shrinkage, chromatin condensation, and plasma membrane asymmetry. This form of cell suicide is appealing as a general biomarker of response in that it is expressed in multiple cell systems (e.g. immune, neuronal, hepatal, intestinal, dermal, reproductive), is conserved phylogenetically (e.g. fish, rodents, birds, sheep, amphibians, roundworms, plants, humans), is modulated by environmentally relevant levels of chemical contaminants, and indicates a state of stress of the organism. Further, apoptosis is useful as a biomarker as it serves as a molecular control point and hence may provide mechanistic information on xenobiotic stress. Studies reviewed here suggest that apoptosis is a sensitive and early indicator of acute and chronic chemical stress, loss of cellular function and structure, and organismal health. Examples are provided of the application of this methodology in studies of health of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes.     

Long-term impact of exotic ants on the native ants of Madeira

Abstract.  1. The earliest exotic records for two notorious invasive ants, the big-headed ant ( Pheidole megacephala ) and the Argentine ant ( Linepithema humile ), both come from the Atlantic islands of Madeira, where the two species underwent population explosions in the 1850s and 1890s respectively. Researchers have long assumed that these invaders spread across all of Madeira and exterminated most or all native ants, despite no research actually documenting such impact.
2. Re-examination of first-hand nineteenth century accounts suggest that P. megacephala and L. humile may never have spread beyond coastal lowland areas, representing < 10% of Madeira's land area. In 2002, native ants dominated most of Madeira; P. megacephala and L. humile were restricted to ≈ 0.3% and ≈ 6% of Madeira's land area respectively.
3. Of the 10 native ant species known from Madeira, only one ( Temnothorax wollastoni ) was not present in 1999–2002 surveys. Although exotic ants may have exterminated T. wollastoni , it seems likely that this species still survives.
4. Thus, even after 150 or more years of residence, P. megacephala and L. humile have come to occupy only a small part of Madeira, and appear to have had little impact.
5. Most of Madeira may be too cool for P. megacephala and perhaps too moist for L. humile to dominate. Also, Madeira's vast natural areas may generally lack weedy vegetation that can support high densities of plant-feeding Hemiptera critical for the ecological dominance of invasive ants. Finally, a dominant native ant, Lasius grandis , inhabiting ≈ 84% of Madeira, may actively exclude P. megacephala and L. humile .     

Self inhibition of the Agaricus bisporus Spore by CO2 and/or γ-Glulaminyl-4-hydroxybenzene and γ-Gtutaminyl-3,4-benzoquinone: A Biochemical Analysis

Chemical and enzymological analyses have been carried out to study the mode of action of CO₂, in inhibiting germination in Agaricus bisporus and to test the suggestion (Vogel and Weaver, 1972. Exp. Cell Res. 75: 95, Vogel et at, 1974. Am. J. Pathol. 76: 165) that γ-glutaminyl-4-hydroxybenzene (GHB) and/or γ-glutaminyl-3,4-benzoquinone (GBQ) would inhibit the succinate dehydrogenase (SDH) in the mushroom spore and thus represent the causal agent(s) of its dormancy. Evidence is presented that the impairment of SDH is brought about by Ihe CO, fixation product oxaloacelate which is formed in the pyruvate carboxylase reaction, and a mechanism is proposed for the release of the SDH inhibition when activating the spores. These are almost devoid of GHB, whereas fruit bodies of all developmental stages contain considerable amounts of the phenol. GBQ is absent in the spore, and its occurrence in mushroom fruit body extracts appears to be an artifact of extraction. Apart from these analytical results, theoretical reasons are given that vouch against the involvement of the phenolics in the inhibition of SDH in vivo.     

EFFECT OF OVIDUCAL PROTEINASE UPON BUFO ARENARUM VITELLINE ENVELOPE. A FLUORESCENCE APPROACH

The intrinsic fluorescence of vitelline envelope from amphibian eggs was enhanced after having been treated with pars recta secretion fluid. At the same time the total number of binding sites for 8-anilino-1-naphthalene sulfonate (ANS) was increased, with the affinity constant remaining unchanged. These observations are interpreted in terms of a structural change of the vitelline envelope submitted to pars recta fluid effect.