Sulfur fractions and carbon-nitrogen-phosphorus-sulfur relationships in some Brazilian and Iowa soils

O atual conhecimento relativo à distribuição em percentagem das várias frações de enxofre nos solos provem principalmente dos estudos dos solos de regiões temperadas. Em vista disso, este estudo foi conduzido para determinar as frações do S e as relações C-N-P-S em alguns solos da região subtropical dos Estados de São Paulo e do Paraná, Brasil, e comparar estes valores nestes solos com aqueles nos solos do Estado de Iowa, dos Estados Unidos da América do Norte. As análises das frações de enxofre nos solos dos dois países, indicaram que os solos do Brasil contem sulfato inorgânico adsorvido. Expressos como percentagem do S total, os solos do Brasil acusaram de 5 a 23% (média 11%) de S-sulfato inorgânico, de 20 a 65% (média 40%) de S-ester sulfato, de 5 a 12% (média 7%) de S-ligado ao Carbono e de 24 a 59% (média 42%) de S orgânico não identificado. As percentagens correspondentes nos solos de Iowa foram de 2 a 8% (média 5%) de S-sulfato inorgânico, de 43 a 60% (média 50%) de S-ester sufato, de 7 a 18% (média 11%) de enxofre ligado ao carbono e de 30 a 39% (média 34%) de S orgânico, não identificado. Outrossim, não foi encontrado o enxofre inorgânico não-sulfato em nenhum dos solos analisados. Houve grandes variações nas relações C, N, Ρ e S entre solos brasileiros quando comparados com aqueles do Iowa.

Taxonomic redescription of the Portuguese man-of-war, Physalia physalis (Cnidaria, Hydrozoa, Siphonophorae, Cystonectae) from Brazil

Although Physalia physalis (Linnaeus, 1758) is widely known from the Brazilian waters, specimens from this coast were never properly described. We describe Brazilian specimens of P. physalis including information on morphology, cnidome, SEM, and histological studies. Taxonomical issues concerning the development of the colonies and eventual synonymy with Physalia utriculus (La Martinière, 1787) are also added.

Vocalizations and comments on the relationships of Hypsiboas ericae (Amphibia, Hylidae)

The vocalizations of Hypsiboas ericae (Caramaschi & Cruz, 2000) are described and new information on the external morphology and osteology of the species are presented. H. ericae presents a bony spine in the prepolex and the individuals can present green or brown dorsal color, as other species of the Hypsiboas pulchellus (Duméril & Bibron, 1841) species group. The vocalizations of H. ericae are similar to the vocalizations of Hypsiboas bischoffi (Boulenger, 1887), Hypsiboas guentheri (Boulenger, 1886), and other species in the H. polytaenius (Cope, 1870 "1869") clade of the H. pulchellus species group, but some osteological aspects are different to those found in the majority of the species of this group.

Trophic relationships between macroinvertebrates and fish in a pampean lowland stream (Argentina)

The diet and trophic relationships between the macroinvertebrates Phyllogomphoides joaquini Rodrigues Capítulo, 1992 and Coenagrionidae (Odonata), Chironomidae (Diptera), Diplodon delodontus (Lamarck, 1919) (Bivalvia: Hyriidae), and Pomacea canaliculata (Lamarck, 1822) (Gastropoda: Ampulariidae) and the fishes Pimelodella laticeps Eigenmann, 1917 (Heptapteridae) and Bryconamericus iheringii (Boulenger, 1887) (Characidae) in a temperate lowland lotic system in Argentina were assessed on the basis of gut contents and stable-isotope analyses. The feeding strategies were analyzed by the AMUNDSEN method. Relative food items contribution for the taxa studied indicated a generalist-type trophic strategy. In macroinvertebrates, in general, the values of stable isotope confirmed the result of the analysis of gut contents. With the fish, stable-isotope analysis demonstrated that both species are predators, although B. iheringii exhibited a more omnivorous behaviour. These feeding studies allowed us to determine the trophic relationships among taxa studied. Detritus and diatoms were a principal source of food for all the macroinvertebrates studied. In La Choza stream the particulate organic matter is a major no limited food resource, has a significant influence upon the community.

Bolivian phlebotomines. II Psychodopygus Yucumensis n.sp., a new man-biting phlebotomine sandfly from subandean region (Diptera, Psychodidae)

Psychodopygus yucumensis n.sp., a new species of Phlebotomine sandfly belonging in genus Psychodopygus mang., is described from specimens collected from human bait, in Beni dept., Bolivia. The male is characteristic of the series panamensis, but the female, closely related to P. carrerai carrerai, can be confused with this species ("cryptic species"). Isozyme characterization can determine any specimen of either species, while morphometric analysis shows statistical differences between the two species. P. yucumensis is strongly anthropophilic. A Leishmania braziliensis braziliensis stock was isolated from this new species, indicating that it is one of the vectors of mucocutaneous Leishmaniasis in the lowland subandean area.

Structure-function relationships for the interleukin 2 receptor system

Receptors for interleukin 2 (IL-2) esit in at least three forms which differ in their subunit compositio, their affinity for ligand and their ability to mediate a cellular reponse. Type I receptors occur following cellular acitivation and consist of the 55,000 m. w. glycoprotein Tac. These receptors bind IL-2 with a low affinity, do not internalize ligand and have not been definitively associated with any response. Type II receptors, on the other hand, conssit of one or more glycoproteins of 70,000 m. w. which have been termed "beta ([beta]) chains." They bind IL-2 with an intermediate affinity and rapidly internalize the ligand. [Beta] proteins mediate many cellular IL-2-dependent reponses, including the short-term activation of natural killer cells and the induction of Tac protein expression. Type III receptors consist of a ternary complex of the Tac protein, the [beta] chain(s) and IL-2. They are characterized by a paricularly high affinity for ligand association. Type III receptors also internalize ligand and mediate IL-2-dependent responses at low factor concentrations. The identification of two independent IL-2-binding molecules, Tac and [beta], thus provides the elusive molecular explanation for the differences in IL-2 receptor affinity and suggests the potential for selective therapeutic manipulation of IL-2 reponses.

Immunological aspects of host-schistosome relationships

The complex immunological relationships between schistosomes and their vertebrate hosts are considered to be conveniently divisible into four distinct, though interrelated categories: the parasite's vulnerability to, its evasion of, and its exploitation of the host's immune response, and its stimulation of the host's immune response to produce immunopathology. Some significant recent advances in the first three categories are discussed, as well as their relationships to the fourth category of immunopathology.

Specific treatment of advanced Schistosomiasis liver disease in man: favourable results

One hundred eighty-four patients with hepatosplenic schistosomiasis mansoni from the northeast of Brazil were studied. All were treated with a single dose of Oxamniquine or Praziquantel, and were observed over 6 to 12 months. Special attention was given to the evolution of severe hepatopathy. Favourable results were obtained, particularly with the compensated hepatosplenic form. Hepatic function showed great improvement. Hepatomegaly and splenomegaly were significantly reduced in size, to a greater or lesser extent, in the great majority of patients. The implications of the results obtained are considered below.

First known brazilian species of the genera Scutops and Neoscutops (Diptera: Periscelididae), with comments on the relationships among the species in each genus

Four new species of Periscelididae are described from Brazil - Neoscutops cariri, sp. n., and Scutops marcgrafi sp. n., from the northern extreme of the Atlantic Forest, S. lopesi, sp. n., from southeastern Brazil, and S. goianiensis, from central Brazil. S. chapmani is herein synonymezed to S. fascipennis. A key is provided for the known species of Neoscutops and Scutops. A brief discussion is made about the possiblem phylogenetic relationships among the species of each of these two genera.

Fecundity, parity, and adult feeding relationships among Nyssorhynchus malaria vectors from Venezuela

Relative to their pre-engorgement weights, nulliparous Anopheles nuneztovari consumed significantly smaller blood meals than A. marajoara, A. triannulatus or A. aquasalis. When females were deprived of sugar before blood feeding, only one-quarter of A. nuneztovari, but more than two-thirds of A. marajoara, A. triannulatus and A. aquasalis matured eggs. Sugar feeding before blood, or two sucessive blood meals by sugar-deprived females, increased the proportion of nulliparous a. nuneztovari which developed eggs, but not significantly so. Nearly all individuals of nulliparous, sugar-fed A. marajoara, A. triannulatus and A. aquasalis matured eggs after one blood feeding. Among A. nuneztovari, A. marajoara and A. aquasalis that matured some eggs in the laboratory, there were no positive correlations between the number of eggs developed and relative vlood mealsize. However, blood meals larger than the mean size significantly increased the chance that A. nuneztovari would develop some eggs. Mean fecundities of gravid A. nuneztovari and A. marajoara reared in the laboratory were significantly lower than those of the same species captured at human bait in nature. Post-engorgement access to sugar by A. nuneztovari (captured at human bait) did not influence fecundity, but significantly enhanced survivorship and the proporticon of individuals which retained eggs. Release-recapture experiments revealed that relatively small blood meals are typical of A. nuneztovari only during the first gonotrophic cycle. We suggest that multiple blood feeding, seemingly necessary for most A. nuneztovari to develop a first clutch of eggs, may increase the probability of infection with Plasmodium vivax where this mosquito species is a primary vector.

Development of Ascaris lumbricoides eggs from females eliminated after chemotherapy in man

The development of Ascaris lumbricoides eggs obtained from females eliminated after treatment of infected individuals with a single oral dose of the antihelminthic drugs thiabendazole (50 mg/kg - 33 patients) or levamisole (250 mg - independent of body weigth - 20 patients) was studied. Every female eliminated up to 72 h after treatment were dissected, the uterus isolated and sectioned into small fragments. The eggs were transferred to plastics tubes and incubated at 28 degrees centigrades in 0.1 N H2 SO4 for 100 days. Every 20 days, starting from the 20 th up to the 100 th day, the extent of egg embryonation ratio was determined. The culture of A. lumbricoides eggs obtained from females from patients treated with thiabendazole did not contain embryonated eggs until the final period of observation. In contrast, the eggs obtained from females eliminated by patients treated with levamisole (control) presented an embryonation rate of 0.0 - 98.0% in the same period.

Evaluation of some organic compounds on bloodstream forms of Trypanosoma cruzi

Accidental transmission of Chagas' disease to man by blood transfusion is a serious problem in Latin-America. This paper describes the testing of several synthetic, semi-synthetic, and natural compounds for their activity against blood trypomastigotes in vitro at 4-C. The compounds embody several types of chemical structures: benzoquinone, naphthoquinone, anthracenequinone, phenanthrenequinone, imidazole, piperazine, quinoline, xanthene, and simple benzenic and naphthalenic derivates. Some of them are for the first time tested against Trypanosoma cruzi. The toxic effect these compounds on this parasite was done by two quite distinct sets of experiments. In one set, the compounds were added to infected blood as ethanolic solution. In this situation the most active one was a furan-1, 2-naphthoquinone, in the same range as gentian violet, a new fact to be considered in the assessment of structure-activity relationships in this class of compounds. In other set, we tentatively evaluated the biological activity of water insoluble compounds by adding them in a pure form without solvent into infected blood. In this way some appear to be very active and it was postulated that the effectiveness of such compounds must result from interactions between them and specific blood components.