Aspectos interessantes observados na meiose de alguns hemípteros

Particular aspects of the meiosis of two species of Hemiptera, namely Megalotomus pallescens (Stal) (Coriscidae) and Jadera sanguinolenta (Fabr.); (Corizidae) are described and discussed in this paper. Megalotomus pallescens This species has primary spermatocytes provided with 7 autosomal tetrads plus a single sex chromosome. The X is smaller than the autosomes and may be found either in the periphery of the circle formed by the autosomal tetrads or in the center together with the m-tetrad which always occupies this position. The X chromosome - In the primary spermatocytes this element, which is tetradiform, orients itself parallelly to the spindle axis and divides transversely by its median constriction. In the secondary spermatocytes it passes undivided to one pole. The m-chromosomes - These chromosomes have been frequently found in close association with the sex chromosome in nuclei wich have passed the diffuse stage, a fact which was considered as affording some evidence in support of the idea /developed by the present writer in another paper with regard to the origin of the m-chromosomes from the sex chromosome. Formation of tetrads - Tetrads appear at first as irregular areas of reticular structure, becoming later more and more distinct. Then, two chromosomal strands very loose and irregular in outline, connected whit each other by several transverse filaments, begin to develop in each area. Growing progressively shorter, thicker and denser, these strands soon give origin to typical Hemiptera tetrads. Jadera sanguinolenta Spermatogonia of this species have 13 chromosomes, that is, 10 autosomes, 2 m-chromosomes and one sex chromosome, one pair of autosomes being much larger than the rest. Chromosomes move toward the poles with both ends looking to them. Primary spermatocytes show 6 tetrads and a single X. The sex chromossome in the first division of the spermatocytes divides as if it was a tetrad, passing undivided to one pole in the second division. In the latter it does not orient, being found anywhere in the cells. Its most common situation in anaphase corresponds therefore to precession. Tetrads are formed here in an entirely different way : the bivalents as they become distinct in the nuclei which came out. of the diffuse stage they appear in form of two thin threads united only at the extremities, an aspect which may better be analized in the larger bivalent. Up from this stage the formation of the tetrads is a mere process of shortening and thickening of both members of the pair. Due to the fact that the paired chromosomes are well separated from each other throughout their entire lenght, the author concluded that chiasmata, if present, are accumulated at the very ends of the bivalents. If no chiasmata have been at all formed, then, what holds together the corresponding extremities must be a strong attraction developed by the kinetochores. If one interprets the bivalents represented in the figures 17-21 as formed by four chromatids paired by one of the ends and united by the opposite one, then the question of the diffuse attachment becomes entirely disproved since it is exactly by the distal extremities that the tetrads later will be connected with the poles. In the opinion of the present writer the facts referred to above are one of the best demonstration at hand of the continuity of the paired threads and at the same time of the dicentricity of Hemiptera chromosomes. In view of the data hitherto collected by the author the behavior of the sex chromosome of the Hemiptera whose males are of the XO type may be summarized as follows: a) The sex chromosome in the primary metaphase appears longitudinally divided, without transverse constriction. It is oriented with the extremities in the plane of the equator and its chromatids separate by the plane of division. (Euryophthalmus, Protenor). In the second division the sex chromosome, provided as it is with an active kinetochore at each end, orients itself with its lenght parallelly to the spindle axis and passes undivided to one pole (Protenor?), or loses to the other pole a centric end (Euryophthalmus) In the latter case it has to become dicentric by means of a longitudinal spliting beginning at the kinetochore. b) The sex chromosome in the primary metaphase is tetradiform, that is, it is provided with a longitudinal split and a median transverse constriction. Orients with its length paral lelly to the spindle axis (what is probably due to the kinetochores being not yet divided) and divides transversely. (Corizas hyalinus, Megalotomus pallescens). in the secondary metaphase the sex chromosome which turned to be dicentric in consequence of a longitudinal spliting initiated in the kineto chore, orients perpendicularly to the equatorial plane and without losing anyone of its extremities passes undivided to one pole (Megalotomus). Or, distending between both poles passes to one side, in which case it loses one of its ends to the other side. (Corizas hyalinus). c) The very short sex chromosome in the first division of the spermatocytes orients in the same manner aa the tetrads and divides transversely. In the second division, due to the inactivity o the inetochore, it remains monocentric and motionless anywhere in the cell, finishing by being enclosed in the nearer nucleus. In the secondary telophase it recuperates its dicentricity at the same time as the autosomal chromatids. (Jadera sanguinolenta, Diactor bilineatus). d) The sex chromosome in the first division orients in the equador with its longitudinal axis parallelly to the spindle axis passing integrally to one pole or, distending itself between the anaphase plates, loses one of its ends to the opposite pole. In this case it becomes dicentric in the prometaphase of the second division, behaving in this division as the autossomes. It thus divides longitudnally. (Pachylis laticomis, Pachylis pharaonis).

Oviposition behaviour of Gryon gallardoi (Hymenoptera, Scelionidae) on eggs of different ages of Spartocera dentiventris (Hemiptera, Coreidae)

The oviposition behaviour of Gryon gallardoi (Brèthes, 1914) on eggs of Spartocera dentiventris Mendonça Jr. (Berg, 1884) of different ages (2, 3, 4, 5, 6, 7, 8 and 12 days) was investigated. Groups of 12 eggs of each age were exposed to single females of G. gallardoi, and the oviposition behaviour was recorded under a stereomicroscope for two hours. Ten replicates were used for each age. In order to identify the moment the parasitoid egg was released inside the host, 1-day old eggs of S. dentiventris were exposed to G. gallardoi females, and the oviposition was interrupted at intervals of 20, 40, 60, 80, 100, 120, 140 and 160s after ovipositor insertion had initiated. Five behavioural steps were recorded: drumming, ovipositor insertion, marking, walking and resting. The average drumming and ovipositor insertion times increased with the host age (P<0.01). Ovipositor insertion usually occurred next to the longitudinal extremities of the host eggs. Marking took on average 19.5 ± 0.7s, and as walking and resting, was not affected by host age. Self-parasitism behaviour was observed in only 13.8 ± 2.3% of the eggs, being more evident with increasing patch depletion (reduction in non-parasitized eggs in the egg group, P<0.01), again with no variation due to changes in host egg age. For all ages tested, self-parasitized host eggs were less frequently contacted and accepted than non-parasitized ones (P<0.01). The parasitoid egg was released 137.0 ± 3.7s after ovipositor insertion. Spartocera dentiventris egg condition can lead to parasitoid behavioural changes, especially during the process of host choice and discrimination.

Experiences with the control of schistosomiasis mansoni in two foci in Central Africa

Experiences with population-based chemotherapy and other methods for the control of schistosomiasis mansoni in two subsaharan foci are described. In the forest area of Maniema (Zaire), intense transmission of Schistosoma mansoni, high prevalences and intensities of infection, and important morbidity have been documental. Taking into account the limited financial means and the poor logistic conditions, the control strategy has been based mainly on targeted chemotherapy of heavily infected people (>600 epg). After ten years of intervention, prevalences and intensities have hardly been affected, but the initial severe hepatosplenic morbidity has almost disappeared. In Burundi, a national research and control programme has been initiated in 1982. Prevalences, intensities and morbidity were moderate, transmission was focal and erratic in time and space. A more structural control strategy was developed, based on screening and selective therapy, health education, sanitation and domestic water supply. Prevalences and intensities have been considerably reduced, though the results show focal and unpredicatable variations. Transmission and reinfection were not signifcantly affected by chemotherapy alone, and eventual outcome of repeated selective treatment appears to be limited by the sensitivity of the screening method. Intestinal morbidity was strongly reduced by community-based selective treatment, but hepatosplenic enlargement was hardly affected; this is possibly due to the confounding impact of increasing malaria morbidity. The experiences show the importance of local structures and conditions for the development of an adapted control strategy. It is further concluded that population-based chemotherapy is a highly valid tool for the rapid control of morbidity, but should in most operational conditions not be considered as a tool for transmission control. Integration of planning, execution and surveillance in regular health services...

Human schistosomiasis mansoni: studies on in vitro granuloma modulation

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to delayed hipersensitivity that results in granulomatous inflamatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflamatory disease is appsrently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor transactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We repport here on experiments wich extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the present of intact (F(ab')2 immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals. These data support the hypothesis that anti-SEA cross reactive idiotypes are important in regulating granulomatous hypersensitivy in chronic intestinal schistosomiasis patients and these cross-reactive idiotypes appear to play a major role in cell-cell interactions which result in the regulation of anti-SEA cellular immune responses.

Adult abundance, biting behavior and parity of Anopheles aquasalis, Curry 1932 in two malarious areas of Sucre State, Venezuela

The principal vector of malaria in eastern Venezuela, Anopheles aquasalis, is exophagic and exophilic. Control using indoor insecticide house sprays has failed to lower the number of malaria cases. Therefore, studies were initiated in two villages of the eastern coastal state of Sucre to better understand this vector's biology and develop a more integrated control program. An. aquasalis was found to have a crepuscular biting behavior with a major peak at dusk and a minor peak at dawn. Mosquitos were collected more outdoors than indoors. Forty-seven percent of the biting took place before people went to bed (22:30 hr) and 69% of the mosquitos biting during this time period bite outdoors. Outdoor biting could be the reason why indoor spraying alone did not lower malaria cases. Seasonal abundance was greater in the rainy season compared to the dry season. Seasonal parous rates were high (78.3%-100%) and similar indoors and outdoors and between dry and wet season in Santa F e. In Guayana, the seasonal parity was lower (34.6%-42.2%) than Santa F e with indoor parity slightly higher than outdoors. Malaria cases were higher in Santa F e, but adult mosquito density was much lower than in Guayana. This difference could have been due to higher parity in Santa F e compared to Guayana. The greater distance to the nearest breeding site and presence of alternative hosts in Guayana can not be discounted as factors which contributed to the difference in malaria transmission between locations. We concluded that knowledge on seasonal occurrence, biting activity, resting behavior and breeding site location can be used to design a new control strategy for this vector.

Sequencing and identification of expressed Schistosoma mansoni genes by random selection of cDNA clones from a directional library

We have initiated a gene discovery program in Schistosoma mansoni based on the technique of Expressed Sequence Tags (ESTs), i.e. partial sequences of cDNAs obtained from single passes in automatic DNA sequencers. ESTs can be used to identify genese onf the basis of their homology whith sequences from other species deposited in DNA or protein databases. Trasncripts with sequences without matches in teh databases may represent novel parasite-specific genes. This approach has shown to be very efficient and in less than two years a broad range of novel genes has already been ascertained, more than doubling the number of known S. mansoni genes.

Establishment and Characterization of a Cell Line from the Mosquito Anopheles albimanus (Diptera: Culicidae)

A new cell line designated LSB-AA695BB, was established from embryos of the mosquito Anopheles albimanus. The primary culture was initiated in April, 1995, and the first passage was made 48 days later. Serial subcultures of the cells have been carried through 90 passages from Abril 1995 to February 1996. The cells were grown at 28°C in MK/VP12 medium, supplemented with 20% fetal bovine serum; the pH tolerance ranged between 6.8 to 7.0. The cells have also been adapted to MM/VP12 medium under the same pH, temperature and serum concentration. The majority of the cells were a fibroblast-type. Isozyme characterization showed a pattern similar to that of An. albimanus pupae and adults but distinct from Ae. taeniorhynchus and Ae. albopictus (C6/36) mosquito cell lines. The culture was shown to be free of mycoplasma, bacteria and fungi. Microsporidia contamination of transovarial transmission was controlled with 6.0 mg/ml of albendazole

Sensitivity of Leishmania spp. to Glibenclamide and 4-Aminopiridine: A Tool for the Study of Drug Resistance Development

We have demonstrated that Leishmania spp. grown as promastigotes, are sensitive to the K+ channel inhibitors 4-aminopyridine and glibenclamide. Their host cells, the macrophages, are not affected by similar concentrations of the drugs. We have also initiated the molecular characterization of the mechanisms involved in the development of drug resistance to glibenclamide by the parasite. Therefore, we have selected experimentally and begun to characterize the Venezuelan Leishmania (Leishmania) strain, NR resistant to glibenclamide [NR(Gr)]. The analysis of genomic DNA evidenced the existence of a fragment which apparently is amplified in NR(Gr). The fragment recognized by the pgpA probe, related to the Leishmania P-glycoprotein family and which was originally isolated from L. tarentolae, showed a size polymorfism between the sensitive and the resistant strain. These results suggest that the development of resistance to glibenclamide in the strain NR(Gr) might be associated with the amplification of the ltpgpA or related gene(s)

Parasite Genome Projects and the Trypanosoma cruzi Genome Initiative

Since the start of the human genome project, a great number of genome projects on other "model" organism have been initiated, some of them already completed. Several initiatives have also been started on parasite genomes, mainly through support from WHO/TDR, involving North-South and South-South collaborations, and great hopes are vested in that these initiatives will lead to new tools for disease control and prevention, as well as to the establishment of genomic research technology in developing countries. The Trypanosoma cruzi genome project, using the clone CL-Brener as starting point, has made considerable progress through the concerted action of more than 20 laboratories, most of them in the South. A brief overview of the current state of the project is given

Molecular characterisation of intermediate snail hosts and the search for resistance genes

The relationship between schistosomes and their intermediate hosts is an extremely intricate one with strains and species of the parasite depending on particular species of snail, which in turn may vary in their susceptibility to the parasites. In order to gain a better understanding of the epidemiology of the disease we have been investigating the use of molecular markers for snail identification and for studying host-parasite relationships. In this paper we will draw on examples concerning schistosomiasis in West and East Africa to illustrate how a molecular analysis can be used as part of a "total evidence" approach to characterisation of Bulinus species and provide insights into parasite transmission. Particular emphasis is given to ribosomal RNA genes (rRNA), random amplified polymorphic DNA (RAPDs) and the mitochondrial gene cytochrome oxidase I (COI). Snails resistant to infection occur naturally and there is a genetic basis for this resistance. In Biomphalaria glabrata resistance to Schistosoma mansoni is known to be a polygenic trait and we have initiated a preliminary search for snail genomic regions linked to, or involved in, resistance by using a RAPD based approach in conjunction with progeny pooling methods. We are currently characterising a variety of STSs (sequence tagged sites) associated with resistance. These can be used for local linkage and interval mapping to define genomic regions associated with the resistance trait. The development of such markers into simple dot-blot or specific PCR-based assays may have a direct and practical application for the identification of resistant snails in natural populations.

Analysis of ancient DNA from coprolites: a perspective with random amplified polymorphic DNA-polymerase chain reaction approach

The aim of this work was to determine approaches that would improve the quality of ancient DNA (aDNA) present in coprolites to enhance the possibility of success in retrieving specific sequence targets. We worked with coprolites from South American archaeological sites in Brazil and Chile dating up to 7,000 years ago. Using established protocols for aDNA extraction we obtained samples showing high degradation as usually happens with this kind of material. The reconstructive polymerization pretreatment was essential to overcome the DNA degradation and the serial dilutions helped with to prevent polymerase chain reaction (PCR) inhibitors. Moreover, the random amplified polymorphic DNA-PCR has been shown to be a reliable technique for further experiments to recover specific aDNA sequences.

Good bug, bad bug: in the case of enteric inflammatory disease does the epithelium decide?

Many studies demonstrate that intestinal inflammation is either initiated or exaggerated by a component of the normal microbiota, most likely commensal bacteria or products derived from these organisms. We review the nature of human inflammatory bowel disease, the evidence for the involvement of the normal bacterial flora in these disorders and the relevance of maintaining the integrity of the epithelial barrier. Moreover, we, and others, have shown abnormal mitochondria structure in tissue resections from patients with inflammatory bowel disease and tissues from rodents that demonstrated psychological stress-induced increases in epithelial permeability. Thus, we also consider the possibility that a defect in epithelial mitochondrial function would predispose an individual to respond to their commensal bacteria flora - no longer considering them as a beneficial passive inhabitant, but rather perceiving them as a threatening and pro-inflammatory stimulus. In support of this postulate, we discuss our recent findings from an in vitro model showing that the human colon-derived T84 cell line exposed to the metabolic stressor, dinitrophenol, and the non-pathogenic, non-invasive, Escherichia coli (strain HB101) display a loss of barrier function, increased signal transduction and increased production of the chemokine, interleukin 8.

An analysis of the impact of the Schistosomiasis Control Programme in Brazil

The impact of the Schistosomiasis Control Programme (PCE) in Brazil was analyzed, covering the period 1976 to 2003, using the following indicators: percentage of Schistosoma mansoni carriers detected among the population examined in the coproscopic surveys (PPS): mortality rate for schistosomiasis, per 100,000 inhabitants (TME): hospitalization rate for schistosomiasis, per 100,000 inhabitants (TIE): average age of deaths caused by schistosomiasis (IMOE). There was a 38.5% reduction in the PPS after the introduction of the PCE, attributed to the treatment of carriers. Even in hyper-endemic municipalities, such as Conde and Cuitegí, in the state of Paraíba, the PPS fell more than 50% after the first year of treatment. The parasitic burden of the carriers also decreased in the two municipalities. The TME was reduced by 63.4% and the TIE by 77.3%. The mortality rate was highest among the 50-and-above age group. The country×s IMOE rose 32.3%. The IMOE was seen to be much lower in the state of Minas Gerais, where the PCE was only initiated in 1983, with very limited coverage.

Paleopathology of the commoners at Tell Amarna, Egypt, Akhenaten's capital city

The Egyptian Pharaoh Akhenaten initiated worship of a single god and established a new capital city (Tell Amarna) that was built and occupied only once from 1350-1330 BCE. This single short occupation offers a unique opportunity to study a short time period. The royal tombs have long been known and studied, but the location of graves for the common inhabitants has been an archaeological puzzle for more than 50 years. Recently four cemeteries have been located and the analysis of commingled bones from the South Tombs cemetery is presented here. The remains yield the following demographic profile: 53 adults with 19 females and 18 males; 14 juveniles between the ages of 5 and 17; and 3 infants. Arthritis and degenerative joint disease of the spine and joints indicates that DJD was not excessive. Only 2 to 8% of the adult population exhibits arthritis. There are 3 healed fractures of the arm (2 to 8% of the adult sample). There is 1 healed compressed fracture of the skull suggesting violence. The adult infection rate is between 2 and 8% with 3 healed and 1 active case of periostitis and no severe infections. Anemia is implicated by 23% of adult frontals exhibiting cribra orbitalia. Life for the common residents of Amarna appears to not have been as good as initially postulated.

Sexually transmitted infections, bacterial vaginosis, and candidiasis in women of reproductive age in rural Northeast Brazil: a population-based study

Population-based data on sexually transmitted infections (STI), bacterial vaginosis (BV), and candidiasis reflect the epidemiological situation more accurately than studies performed in specific populations, but such data are scarce. To determine the prevalence of STI, BV, and candidiasis among women of reproductive age from a resource-poor community in Northeast Brazil, a population-based cross sectional study was undertaken. All women from seven hamlets and the centre of Pacoti municipality in the state of Ceará, aged 12 to 49 years, were invited to participate. The women were asked about socio-demographic characteristics and genital symptoms, and thereafter examined gynaecologically. Laboratory testing included polymerase chain reaction (PCR) for human papillomavirus (HPV), ligase chain reaction (LCR) for Chlamydia trachomatis and Neisseria gonorrhoeae, ELISA for human immunodeficiency virus (HIV), venereal disease research laboratory (VDRL) and fluorescent treponema antibody absorption test (FTA-ABS) for syphilis, and analysis of wet mounts, gram stains and Pap smears for trichomoniasis, candidiasis, and BV. Only women who had initiated sexual life were included in the analysis (n = 592). The prevalences of STI were: HPV 11.7% (95% confidence interval: 9.3-14.7), chlamydia 4.5% (3.0-6.6), trichomoniasis 4.1% (2.7-6.1), gonorrhoea 1.2% (0.5-2.6), syphilis 0.2% (0.0-1.1), and HIV 0%. The prevalence of BV and candidiasis was 20% (16.9-23.6) and 12.5% (10.0-15.5), respectively. The most common gynaecological complaint was lower abdominal pain. STI are common in women in rural Brazil and represent an important health threat in view of the HIV pandemic.