Isolation of a distally located gene possibly correlated with gametocyte production ability

Previous studies were focussed on the attempt to correlate observable variations in the size of Plasmodium berghei chromosomes with the loss of ability to produce viable gametocytes. A temporal coincidence between the appearance of a subtelomeric deletion on P. berghei chromosome 5 and the loss of the ability to produce viable gametocytes was observed in a clone (HPE) directly derived from the high gametocyte-producer clone 8417 during mechanical passages. Interestingly enough, three P. berghei sexual-specific genes have already been mapped on internal fragments of this chromosome. A novel gene, clone 150, isolated from a genomic library of clone 8417 using a probe enriched for sexual-specific transcripts, maps on chromosome 5 within 100kb from the telomere. Subtelomeric deletions of chromosome 5 affecting two non-producer clones involve part of the transcribed region of this gene.

Attempted isolation of the gene encoding the 21 Kd Plasmodium berghei ookinete transmission blocking antigen from Plasmodium yoelli and Plasmodium vivax

The 21kD ookinete antigen of Plasmodium berghei (Pbs 21) has been shown to elicit an effective and long lasting transmission blocking immune response in mice. Having cloned and sequenced this antigen (Paton et al. 1993) the sequence was compared to the genes of the same family previously identified in P. falciparum, P. gallinaceum (Kaslow et al. 1989) and P. reichenowi (Lal et al. 1990). Four conserved areas were identified in this comparison, to which degenerate oligonucleotides were designed. PCR amplification and screening of genomic libraries was then carried out using these oligonucleotides. The P. yoelii gene was successfully cloned and a number of novel P. vivax genes identified but the P. vivax homologue of Pbs21 remains elusive.

Effects of three organophosphorus insecticides in the reproductive potential of Culex quinquefasciatus

A Culex quinquefasciatus Say 1823 strain with resistant genes to organophosphates was tested in the laboratory to know the reproductive potential after exposure, as larvae, at the LC30 and LC70 (mg/l) of three organophosphorus insecticides: malathion, chlorpyrifos and methyl-pirimiphos. Data showed that fecundity was decreased significantly by malathion at LC30 = 0.0025 and LC70 = 0.0075, whereas fertility has a no significant decrement by chlorpyrifos and methyl-pirimiphos at the LC70 (0.000016, 0.00043). The sexual index was affected by chlorpyrifos and methyl-pirimiphos showing a greater number of adult females.

Primary isolation of spotted fever group rickettsiae from Amblyomma cooperi collected from Hydrochaeris hydrochaeris in Brazil

This paper reports the first isolation of a spotted fever group rickettsia from an Amblyomma cooperi ixodid collected from a capybara (Hydrochaeris hydrochaeris) in an endemic area of spotted fever in the County of Pedreira, State of São Paulo, Brazil. Isolation was performed in Vero cell culture and submitted to immunofluorescence, using antibody from Rickettsia rickettsii-positive human serum.

Trypanosoma cruzi in the anal glands of urban opossums: I- isolation and experimental infections

Opossums (Didelphis marsupialis) captured in intensely urbanized areas of the city of Caracas, Venezuela, were found infected with Trypanosoma cruzi. The developmental cycle of trypomastigote-epimastigote-metacyclic infective trypomastigote, usually occurring in the intestine of the triatomine vector, was taking place in the anal odoriferous glands of the opossums. Material from the glands, inoculated in young, healthy opossums and white mice by different routes, subcutaneously, intraperitoneally, orally, and into the eye, induced T. cruzi infections in all animals. Parasitemia, invasion of cardiac and skeletal muscle, and intracellular multiplication of amastigotes were observed. Inoculation of metacyclics from anal glands, cultured in LIT medium, gave equivalent results. All opossums survived; all mice died. Excreta of opossums may thus transmit Chagas' disease by contamination, even in urban areas where insect vectors are not present.

Isolation of fungi from nature in the region of Botucatu, state of São Paulo, Brazil, an endemic area of paracoccidioidomycosis

In an attempt to isolate Paracoccidioides brasiliensis from nature 887 samples of soil from Botucatu, SP, Brazil, were collected cultured in brain heart infusion agar supplemented with dextrose, in potato dextrose agar and in yeast extract starch dextrose agar, all with antibiotics, at 25º and 37ºC. Five thermo-dependent dimorphic fungi morphologically resembling P. brasiliensis were isolated; two from armadillo holes; further studies of the biology, antigenicity and genetic features of the five dimorphic fungi are necessary to clarify their taxonomy and their possible relation to P. brasiliensis. In addition, 98 dematiaceous fungi and 581 different species of Aspergillus spp. were also isolated. Our findings emphasize that armadillos and their environment are associated with thermo-dimorphic fungi and confirm the ubiquity of pathogenic dematiaceous fungi and Aspergillus spp.

Morphology and Histology of the Female Reproductive System of Abedus ovatus Stal (Belostomatidae: Hemiptera: Insecta)

In Abedus ovatus Stal, the female reproductive system consists of a pair of ovaries leading to oviduct and opens out by genital aperture. Each ovary is composed of five telotrophic ovarioles, with four different regions, terminal filament, germarium, vitellarium and pedicel. Germarium and vitellarium are the germ tubes in which the development of oocyte occurs. In the germarium, the differentiation of trophocytes into young oocytes was observed in three zones, ZI, ZII and ZIII. Further development of oocytes in the vitellarium could be divided into seven stages, STI STVII. The developed eggs are lodged in the pedicel

Density-dependent pollen limitation and reproductive assurance in a wind-pollinated herb with contrasting sexual systems

1. Wind pollination is thought to have evolved in response to selection for mechanisms to promote pollination success, when animal pollinators become scarce or unreliable. We might thus expect wind-pollinated plants to be less prone to pollen limitation than their insect-pollinated counterparts. Yet, if pollen loads on stigmas of wind-pollinated species decline with distance from pollen donors, seed set might nevertheless be pollen-limited in populations of plants that cannot self-fertilize their progeny, but not in self-compatible hermaphroditic populations.2. Here, we test this hypothesis by comparing pollen limitation between dioecious and hermaphroditic (monoecious) populations of the wind-pollinated herb Mercurialis annua.3. In natural populations, seed set was pollen-limited in low-density patches of dioecious, but not hermaphroditic, M. annua, a finding consistent with patterns of distance-dependent seed set by females in an experimental array. Nevertheless, seed set was incomplete in both dioecious and hermaphroditic populations, even at high local densities. Further, both factors limited the seed set of females and hermaphrodites, after we manipulated pollen and resource availability in a common garden experiment.4. Synthesis. Our results are consistent with the idea that pollen limitation plays a role in the evolution of combined vs. separate sexes in M. annua. Taken together, they point to the potential importance of pollen transfer between flowers on the same plant (geitonogamy) by wind as a mechanism of reproductive assurance and to the dual roles played by pollen and resource availability in limiting seed set. Thus, seed set can be pollen-limited in sparse populations of a wind-pollinated species, where mates are rare or absent, having potentially important demographic and evolutionary implications.

Reproductive Aspects of Haemaphysalis leporis-palustris

The adult stage of Haemaphysalis leporis-palustris was studied. Two infestations consisted of male and female ticks on two rabbits (Oryctolagus cuniculus). Other two infestations consisted of only female ticks on two O. cuniculus. Females fed without males showed differences in some biological parameters when compared to females fed with males. Parthenogenesis is reported for the first time by one H. leporis-palustris female

The lack of effect of insulin on luteinizing hormone pulsatility in healthy male volunteers provides evidence of a sexual dimorphism in the metabolic regulation of reproductive hormones.

BACKGROUND: The activity of the neuroendocrine reproductive axis is closely related to nutritional status. This link is particularly important in healthy women, in whom insulin is a positive signal for the reproductive system. In contrast, very little is known regarding this relation in men. OBJECTIVES: This study was designed to evaluate the effect of insulin on the reproductive axis of young male volunteers and to study the effect of short-term hypercaloric feeding on this modulation. DESIGN: The activity of the neuroendocrine reproductive axis was characterized by the pattern of endogenous luteinizing hormone (LH) secretion on the basis of frequent blood sampling protocols. The effect of insulin was tested by comparing the LH secretion pattern between a baseline study and a hyperinsulinemic euglycemic clamp. These studies were performed first in subjects fed a controlled isocaloric diet for 6 d (calculated as 1.5 times their resting metabolic rate) then in the same subjects fed a controlled hypercaloric diet in which 30% extra calories were provided as fat and fructose (3 g · kg(-1) · d(-1)) before undergoing identical protocols. Serum gonadotropins, sex steroids, glucose, insulin, ghrelin, and leptin concentrations were assessed, and the HOMA-IR was calculated. RESULTS: The LH secretion pattern was not affected by insulin or by hypercaloric feeding. Insulin decreased ghrelin and increased leptin concentrations but had no additional effect of hypercaloric feeding despite significantly lower HOMA-IR indexes. CONCLUSIONS: Our data indicate that neither insulin nor short-term hypercaloric feeding has any effect on the activity of the male reproductive axis. They also further support the association between ghrelin and insulin and glucose metabolism. This trial was registered at clinicaltrials.gov as NCT01058681.

Life Cycle and Reproductive Patterns of Triatoma rubrofasciata (De Geer, 1773) (Hemiptera: Reduviidae), under Laboratory Conditions

The life cycle and reproductive patterns of Triatoma rubrofasciata were studied along with laboratory conditions for the establishment of a prolific colony. The insects were divided into four groups: two of them were maintained at room temperature (20.5°C to 33°C and 85% ± 5% of relative humidity), the other two in a climatic chamber (CC) (temperature: 29°C, humidity: 80% ± 5%). The groups were fed weekly or fortnightly on Swiss mice. The females from the group kept in the CC and fed weekly had longer life span, as well as a higher number of eggs, fertile eggs and hatchings; the group kept in the CC and fed fortnightly had a shorter life span for the 1st, 2nd and 3rd instars and a lower mortality rate for all instars. It was concluded that a constant high temperature (CC at 29°C) is the most suitable condition for the maintenance of a colony of T. rubrofasciata regardless of the interval between repasts.