Metabolic response of cerambycid beetle (Morimus funereus) larvae to starvation and food quality

The response of xylophagous Morimus funereus larvae to a direct change of diet demonstrated that the larvae from nutrient-poor substrates, e.g. oak, are very sensitive to such a change. Depending on dietary protein quality and quantity, an increase of proteolytic activity, i.e. an intensified protein metabolism accompanied by changes in body mass gain, was observed. At the same time, amylolytic activity was usually decreased. In the larvae reared on Robert's diet, sensitivity to the switch in diet was lower at the level of proteolytic enzymes that remained at the control level, while amylolytic activity was elevated. If the switch to a new diet was preceded by 7-day-starvation that disturbed nutritional homeostasis, the response of the larvae was similar to that recorded upon a direct switch only after short-term feeding (24 h) upon starvation. Differences in the response to changes in the diet of the larvae from nature, those reared under laboratory conditions and those of different physiological status could be ascribed to plasticity in the expression of the genes coding for proteases and their isoenzymes, as well as to the multi-functionality of some neurosecretory neurons, synthetic products that participate in the regulation of digestive enzyme activities.     

Mammalian Pex14p: membrane topology and characterisation of the Pex14p-Pex14p interaction

Peroxisomal biogenesis is a complex process requiring the action of numerous peroxins. One central component of this machinery is Pex14p, an intrinsic peroxisomal membrane protein probably involved in the docking of Pex5p, the receptor for PTS1-containing proteins (peroxisomal targeting signal 1-containing proteins). In this work the membrane topology of mammalian Pex14p was studied. Using a combination of protease protection assays and CNBr cleavage, we show that the first 130 amino acid residues of Pex14p are highly protected from exogenously added proteases by the peroxisomal membrane itself. Data indicating that this domain is responsible for the strong interaction of Pex14p with the organelle membrane are presented. All the other Pex14p amino acid residues are exposed to the cytosol. The properties of recombinant human Pex14p were also characterised. Heterologous expressed Pex14p was found to be a homopolymer of variable stoichiometry. Finally, in vitro binding assays indicate that homopolymerisation of Pex14p involves a domain comprising amino acid residues 147-278 of this peroxin.     

Experimental transmission of Leishmania tropica to hamsters and mice by the bite of Phlebotomus sergenti

Phlebotomus sergenti is a natural vector of Leishmania tropica. However, the ability of P. sergenti to transmit L. tropica by bite has not been proven experimentally yet. We have transmitted L. tropica to golden hamsters and BALB/c mice by the bite of P. sergenti. Sand flies and Leishmania both originated from an anthroponotic cutaneous leishmaniasis focus in Urfa, Turkey. P. sergenti females from a laboratory colony were infected by feeding on lesions of needle-inoculated hamsters or mice. Gravid females were allowed to refeed on uninfected hosts 9-15 d after the infective feeding. At the second feeding, some infected females took a full blood meal, while others only a partial one; some females failed to feed at all. The ability of infected females to take a blood meal did not correlate with the parasite transmissibility. In four BALB/c mice, lesions developed after 1-6 months. In two albino hamsters (Mesocricetus auratus), lesions developed 1 month after the infective feeding, and Leishmania could be reisolated from these sites. Another hamster did not develop a lesion; however, the feeding site and the adjacent ear were PCR positive 1 year after infective feeding. Our results show that dissemination to other parts of host body occurs in L. tropica after sand fly bite. Experimental transmission of the parasite confirms that P. sergenti is a natural vector of L. tropica.     

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county,State of São Paulo,Brazil

This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of S o Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis.     

Different sensitivity to apoptosis in cells of monocytic or lymphocytic origin chronically infected with human immunodeficiency virus type-1

Apoptotic death of CD4+ T lymphocytes is a major cause of the immunodeficiency caused by human immunodeficiency virus (HIV), but it is still unclear how this process precisely occurs. To characterize a potentially useful cellular model, we have analyzed the tendency of chronically HIV-infected CD4+ human cell lines of different origin to undergo apoptosis. We studied ACH-2 and U1 lines, derived from the CD4+ T-cell A301 and the promonocytic U937 cell lines, respectively, and induced apoptosis via several stimuli that trigger different pathways. Their capacity to regulate plasma membrane CD95 expression and to produce soluble CD95 was also analyzed. Using staurosporine, TNF-alpha plus cycloheximide, and gamma-radiations, we observed that ACH-2 were more sensitive to programmed cell death than A301, while U1 were less sensitive than U937. Both infected cell types had a lower sensitivity to CD95-induced apoptosis; the analysis of changes in mitochondrial membrane potential corroborated these observations. Plasma membrane CD95 was similarly regulated in all cell types, which, however, presented a different capacity to produce soluble CD95 molecules. Our in vitro results may offer a new perspective for developing further studies on the pathogenesis of HIV infection. A chronically infected cell line of lymphocytic origin is more susceptible to apoptosis than its parental cell type, while infected monocytic cells are less sensitive than their uninfected counterpart. Thus, it is possible to hypothesize that one of the reasons by which circulating monocytes survive and represent a viral reservoir is the capacity of HIV to decrease the sensitivity to apoptosis of this cell type. However, further studies on ex-vivo collected fresh cells, as well as on other cell lines, are urgently needed to confirm such hypothesis.     

Intraspecific variation in the venoms of the South American rattlesnake (Crotalus durissus terrificus)

The venom of eight individual Crotalus durissus terrificus snakes from the State of Minas Gerais, Brazil, in addition to pooled venom from Butantan Institute, were compared. Snakes were captured in distinct locations, some of them 600 km apart: Conselheiro Lafaiete, Entre Rios de Minas, Itauna, Itapecerica, Lavras, Patos de Minas, Paracatu, and Santo Antonio do Amparo. The crude venoms were tested for proteolytic, phospholipase A2, platelet aggregating, and hemagglutinating activities. The venoms were also analyzed by polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF). Chromatographic patterns of venom proteins on both gel-filtration and anion-exchange chromatographies were also performed. All venoms presented high phospholipase A2 and platelet-aggregating activities, but only minimal hemagglutinating or proteolytic activities were found. Gel-filtration chromatography showed a characteristic profile for most venoms where four main peaks were separated, including the typical ones where convulxin and crotoxin were identified; however, peaks with high amounts of lower molecular weight proteins were found in the venoms from the Santo Antonio do Amparo location and Butantan Institute, characterizing these venoms as crotamine positive. Anion-exchange chromatographies presented a similar protein distribution pattern, although the number of peaks (up to ten) distinguished some venom samples. Consistent with these results, polyacrylamide gels that were silver stained after venom separation by PAGE or IEF presented a similar qualitative band distribution, although a quantitative heterogeneity was detected among venoms. Our results suggest that the variability found in venom components of C. d. terrificus venoms captured in Minas Gerais State may be genetically inherited and/or environmentally induced.     

Ecology of mosquitoes (Diptera: Culicidae) in areas of Serra do Mar State Park, State of São Paulo, Brazil. III. Daily biting rhythms and lunar cycle influence

The ecology of mosquito species (Diptera: Culicidae) was studied in areas of the Serra do Mar State Park, State of S?o Paulo, Brazil. The influence of the lunar cycle and the daily biting rhythms of mosquito populations were analyzed. Systematized biweekly human bait collections were made in a silvatic environment for 24 consecutive months (January 1991 to December 1992). A total of 20,591 specimens of adult mosquitoes belonging to 55 species were collected from 545 catches. Sabethini species were captured exclusively during daylight periods, with the exception of Trichoprosopon digitatum, while members of Anophelinae predominated during nocturnal hours. Members of the subfamily Culicinae that were collected primary during nocturnal periods included Culex nigripalpus, Coquillettidia chrysonotum and Cq. venezuelensis while daytime catches included Psorophora ferox and Ps. albipes. Others members of culicines mosquitoes that were collected during both day and night included: Aedes serratus, Ae. scapularis and Ae. fulvus. Lunar cycles did not appear to influence the daily biting rhythms of most mosquito species in the area, but larger numbers of mosquitoes were collected during the new moon. Ae. scapularis were captured mainly during the full moon.     

The significance of fire intensity in creating local patchiness in the Chilean matorral

The hypothesis that high and low intensity human-made fires can produce ecologically different effects in the Chilean matorral is examined. We compared the abundance of naturally established seedlings under shrubs burned by low and high intensity fires on five north and five south facing slopes. On south facing slopes, we found 54 shrubs burned by low intensity fires and only 4 shrubs burned by high intensity fires. In contrast, north facing slopes had approximately the same number of shrubs burned by low and high fire intensity fires (24 versus 19, respectively). We only found seedlings under shrubs burned by low intensity fires and most of them were of Muehlenbeckia hastulata and Trevoa trinervis. Also viable seeds were only found under shrubs burned by low intensity fires. Results indicate that fire intensity can be an important factor determining species distribution patterns in the matorral.     

Shell Beds as paleoecological puzzles: A case study from the Upper Permian of the Paraná Basin, Brazil

Summary Microstratigraphic, sedimentological, and taphonomic features of the Ferraz Shell Bed, from the Upper Permian (Kazanian-Tatarian?) Corumbataí Formation of Rio Claro Region (the Paraná Basin, Brazil), indicate that the bed consists of four distinct microstratigraphic units. They include, from bottom to top, a lag concentration (Unit 1), a partly reworked storm deposit (Unit 2), a rapidly deposited sandstone unit with three thin horizons recording episodes of reworking (Unit 3), and a shell-rich horizon generated by reworking/winnowing that was subsequently buried by storm-induced obrution deposit (Unit 4). The bioclasts of the Ferraz Shell Bed represent exclusively bivalve mollusks.Pinzonellaillusa andTerraia aequilateralis are the dominant species. Taphonomic analysis indicates that mollusks are heavily time-averaged (except for some parts of Unit 3). Moreover, different species are time-averaged to a different degree (disharmonious time-averaging). The units differ statistically from one another in their taxonomic and ecological composition, in their taphonomic pattern, and in the size-frequency distributions of the two most common species. Other Permian shell beds of the Paraná Basin are simílar to the Ferraz Shell Bed in their faunal composition (they typically contain similar sets of 5 to 10 bivalve species) and in their taphonomic, sedimentologic, and microstratigraphic characteristics. However, rare shell beds that include 2–3 species only and are dominated by articulated shells preserved in life position also occur. Diversity levels in the Permian benthic associations of the Paraná Basin were very low, with the point diversity of 2–3 species and with the within-habitat and basin-wide (alpha and gamma) diversities of 10 species, at most. The Paraná Basin benthic communities may have thus been analogous to low-diversity bivalve-dominated associations of the present-day Baltic Sea. The ‘Ferraz-type’ shell beds of the Paraná Basin represent genetically complex and highly heterogeneous sources of paleontological data. They are cumulative records of spectra of benthic ecosystems time-averaged over long periods of time (10²–10⁴ years judging from actualistic research). Detailed biostratinomic reconstructions of shell beds can not only offer useful insights into their depositional histories, but may also allow paleoecologists to optimize their sampling designs, and consequently, refine paleoecological and paleoenvironmental interpretations.     

Detection of resistance genes and susceptibility patterns in Bacteroides and Parabacteroides strains

Susceptibility to five antimicrobials was determined for Bacteroides spp. (n = 52) and Parabacteroides distasonis (n = 8). All isolates were susceptible to metronidazole. The resistance rates to ampicillin, cefoxitin, tetracycline and clindamycin were 98%, 9.6%, 65.3% and 19.2% of the Bacteroides strains, respectively. The genes cepA, cfiA, cfxA, tetQ, ermF and nim were found in 69.2%, 17.3% 9.6%, 50%, 7.7% and 3.8% for these strains respectively. All P. distasonis strains were resistant to ampicilin. Cefoxitin, tetracycline and clindamycin resistance rates were 75%, 87.5% and 50%, respectively. The ermF and nim genes were absent and 37.5%, 12.5%, 12.5% and 87.5% of this strains possessed cepA, cfiA, cfxA and tetQ genes, respectively. Ten cfiA gene positive strains of Bacteroides and Parabacteroides were submitted to E-test with imipenem and amoxicillin–clavulanate. The resistance rate to imipenem was 4.1% and 8.3% to amoxicillin–clavulanate. This feature is for the first time described in Brazil.