Genetic analysis of signal peptides in amphibian antimicrobial secretions.

Amphibian secretion is an important source of bioactive molecules that naturally protect the skin against noxious microorganisms. Collectively called antimicrobial peptides (AMPs), these molecules have a wide spectrum of action, targeting viruses, bacteria and fungi. Like many membrane and secreted proteins, AMPs have cleavable signal sequences that mediate and translocate the nascent polypeptide chains into the endoplasmic reticulum. Although it is accepted that the signal peptides (SPs) are simple and interchangeable, there is neither sequence nor structure that is conserved among all gene families. They derived from a common ancestor but developed different traits as they adapt to distinct environmental pressures. The aim of this study was to provide anoverview of the diversity of SPs of the frog, taking into account reported cDNA sequences and the evolutionary relationship among them. We analysed more than 2000 records that reported the relative abundance, diversity and evolutionary divergence based on the peptide signals of frog AMPs. We conclude that the physical properties of the sequence are more important than the specific peptidesin AMP SPs. Since there is significant overlapping among related genera, differences in secretion from different peptide types should be regulated by additional levels, such as posttranscriptional modifications or 5-UTR sequences.

Acute and chronic effects of Cr(VI) on Hypsiboas pulchellus embryos and tadpoles.

In the last few years there has been great concern about declines in the abundance of several species of amphibians around the world. Among amphibians, anurans have a biphasic life cycle, with aquatic tadpoles and generally terrestrial adults, and they have an extremely permeable skin, making them excellent indicators of the health of the environment. A number of different causes have been suggested for the global decline of anurans, the pollution of their habitat by chemical stressors being considered one of the major factors. Among chemical stressors, heavy metals are known for their high toxicity at very low concentrations. This study assessed short- (96 h, 'acute') and long-term (1272 h, 'chronic') exposure to Cr(VI) at lethal (3 to 90 mg 1(-1)) and sublethal concentrations (0.001 to 12 mg 1(-1)) on Hypsiboaspulchellus (previously called Hyla pulchella; see Faivovich et al. 2005) tadpoles (Fam. Hylidae) from central eastern Argentina. Fertilized eggs collected from a clean pond near La Plata (Buenos Aires Province) were used for acute and chronic toxicity testing. Assays were done under controlled laboratory conditions. Results of chronic exposure were used to assess the effect of factors such as toxicant concentration and age of organisms at the beginning of exposure on the response variables (growth, development and survival until metamorphosis). Results indicated a higher sensitivity to Cr(VI) of individuals first exposed as tadpoles than those first exposed as embryos during acute and chronic exposure. Exposure to the highest sublethal concentrations (6 to 12 mg 1(-1)) of the toxicant showed early inhibitory effects on growth of all treated organisms compensated at longer exposure periods with an increase in the growth rate compared to the control groups.

Congenital papillomas and papillomatoses associated with the human papilloma virus (HPV)-report on 5 cases.

The authors present a study of five cases of vulvar congenital papillomas and papillomatoses in stillborns and neonates dead upon birth. The studied material was collected from five necropsies. The histopathological evaluation showed hyperkeratosis, acanthosis, papillomatosis, perinuclear haloes, and nuclear abnormalities. In three of the cases, the electron microscopy identified nuclear and cytoplasmatic viral particles ranging from 40 to 60 nm in size, compatible with HPV. The immunohistochemical study of those lesions showed nuclear and cytoplasmatic positivity. The authors concluded that the presence of viral particles suggestive of HPV added to the immunopositivity indicated the possibility of viral infection.

Enterovirus associated placental morphology: a light, virological, electron microscopic and immunohistologic study.

The purpose of this study was to identify the possible effect of enteroviruses on placental tissue. Seventy-eight pregnant women were studied throughout their pregnancy: enteroviral infection was detected by faecal viral isolation and seric neutralization of previously identified virus in cell culture. In 19 cases of confirmed maternal infection, placentae were examined grossly, by optical microscopy, immunohistochemical and electron microscopic methods. Ten term placentae from women included in the study, with no clinical, serological or virological evidence of enteroviral infection, were used as control, and examined by gross and optical microscopy. In 17 specimens (echovirus-coxsackievirus) an haematogenous placentitis was suspected on the basis of gross observation. Microscopic lesions were similar to those found in other viral infections, with specific features. The nature of the inflammatory reaction pointed to the presence of an acute type of haematogenous placentitis, not present in placentae of the control group. The authors (AA) comment on the results and present the hypotheses about the available data: (1) maternal enteroviremia and faecal virus shedding without placental invasion, placentary damage being an unspecific consequence of infection; (2) direct virus-induced injury is not the only possible cause for the lesions: (3) placental enteroviral infection occurred with placental pathology but the virus did not cross the organ as the newborn had no signs of infection.

Congenital echo virus infection--morphological and virological study of fetal and placental tissue.

A prospective study of 78 pregnant women was undertaken to detect maternal enterovirus infection. Maternal faecal specimens and blood samples, placental and fetal tissue were taken for viral study, electron microscopy, histochemistry, and morphological examination. We present the post-mortem findings in three fetuses whose maternal infection was detected before delivery by isolation of ECHO virus type 33 and type 27 from faecal specimens and/or placental and fetal tissues. The morphological aspects were similar in all cases and included an acute infection of the placenta and hypoxic/hypotensive injury to fetal organs. In one case, viral particles were detected by electron microscopy of the fetal liver. This series of cases of intrauterine ECHO virus infection confirms the potential gravity of such infection during pregnancy and the need to prevent enteroviral disease.

Enterovirus isolation from foetal and placental tissues.

Four spontaneous abortions and two stillbirth occurred during a prospective survey following the teratogenicity of echoviruses in 80 pregnant women selected at random from the Antenatal Care Service. Echovirus types 19, 27, and 33. Coxsackie B2 and B6 were isolated from placental and foetal tissues (brain, liver, kidney, heart, and spleen). The mothers also excreted the virus by faeces at least twenty days before abortion and responded serologically, indicating active virus infection. Almost all aborted children were anomalous with signs of viral infection.