Characterization of sodium transport in gustatory epithelia from the hamster and rat

The transduction of sodium salts occurs through a variety of mechanisms, including sodium influx through amiloride-sensitive sodium channels, anion-dependent sodium movement through intercellular junctions and unidentified amiloride-insensitive mechanisms. Characterizations of sodium transport in lingual epithelium mounted in Ussing chambers have focused almost exclusively on epithelia containing only fungiform taste buds. In the present study we have investigated sodium transport by measuring NaCl-induced short-circuit current from lingual epithelia containing fungiform, foliate, vallate and palatine taste buds in the hamster and the rat. All areas show measurable sodium transport, yet significant differences were noted between the epithelia from the rat and the hamster and among the different epithelia within a single species in terms of current density, transepithelial resistance and mucosal amiloride sensitivity. In general, epithelia from the anterior tongue were of a lower resistance and transported sodium more effectively than from the posterior tongue. Moreover, fungiform- and vallate-containing epithelia in the rat had a greater current density than did the corresponding tissues in the hamster. Amiloride sensitivity also differed between the rat and the hamster. In the hamster all gustatory areas showed some amiloride sensitivity, while in the rat the vallate-containing epithelia were devoid of amiloride- sensitive sodium transport. The results are consistent with the interpretation that all chemosensitive areas may participate in the detection of salts but the degree of salt transport and the mechanism of transport is variable among different lingual epithelia and different species.      

Postsettlement growth of two estuarine crab species, Chasmagnathus granulata and Cyrtograpsus angulatus (Crustacea, Decapoda, Grapsidae): laboratory and field investigations

The estuarine grapsid crabs Chasmagnathus granulata and Cyrtograpsus angulatus belong to the most typical and dominant inhabitants of brackish coastal lagoons in southeastern South America. In a combined laboratory and field investigation of juvenile growth, we measured the increase in body size in these species under controlled conditions as well as in field experiments (in Mar Chiquita lagoon, Argentina), seasonal changes in size frequency distribution of a natural population, and growth related changes in selected morphometric traits of male and female juveniles (relations between carapace width, carapace length, propodus height and length of the cheliped, and pleon width). At 24°C, Cy. angulatus grew faster than Ch. granulata; it reached the crab-9 instar (C9; 13 mm carapace width) after 92 days, while Ch. granulata required 107 days to reach the C8 instar (7.4 mm). At 12°C, growth ceased in both species. The pleon begins to show sexual differences in the C5 (Cy. angulatus) and C8 instar (Ch. granulata), respectively, while the chelae differentiate earlier in Ch. granulata than in Cy. angulatus (in C4 vs C6). In the field, growth was maximal in summer, and was generally faster than in laboratory cultures. However, there is great individual variability in size (about 25% even in the first crab instar) and in size increments at ecdysis, increasing throughout juvenile growth. Our data indicate that, in the field, small-scale and short-term variations in feeding conditions, temperature, and salinity account for an extremely high degree of variability in the absolute and relative rates of growth as well as in the time to sexual differentiation. Received in revised form: 20 September 2001 Electronic Publication     

The same HLA-DQ alleles determine either susceptibility or resistance to different coxsackievirus-mediated autoimmune diseases.

An important characteristic of autoimmune diseases is their association with major histocompatibility complex class I and class II alleles. In this study, we compared insulin-dependent diabetes mellitus (IDDM) with idiopathic dilated cardiomyopathy (IDC) from a strictly immunologic perspective. Although the target organs are different, being in one case the insulin-producing beta cells of the pancreas and in the other case the myocytes of the heart, many aspects of the tissue-specific immune destruction are common. Similar yet different Coxsackievirus B strains with either pancreotropic or cardiotropic specificity are able to perpetrate the first injury of the respective target tissue. Their shared capacity of inducing a superantigenic reaction further enhances the damage. Once previously secluded autoantigens are then exposed to the immune system, the tissue injury is completed via a more conventional type of immune response. On the basis of the compounded results we obtained, it is possible to propose that the same HLA-DQ molecules which are able to protect the individuals from IDDM (e.g., HLA-DQA1*0102, DQB1*0602) seem to favour the enteroviral attack to the myocardium, while alleles which confer the strongest susceptibility to IDDM (e.g., DQA1*0301, DQB1*0302), seem unable to sustain the immune attack against the heart.     

Glycine immunoreactive neurons in the medulla oblongata in cats

Using a highly specific antiserum to Glycine and a very sensitive immunohistochemical technique with streptavidin-HRP, we visualized for the first time a considerable number of glycine immunoreactive cell bodies and fibers in the cat medulla oblongata. These results suggest that glycine may play an essential role in nearly all the physiological functions involving the medulla oblongata, including the muscular atonia occurring during paradoxical sleep.     

Diagnosis of aspergillosis: Role of proteomics

The expansion of the antifungal armamentarium and the implementation of imaging techniques and new nonculture-based fungal diagnostics (NCBFDs) have improved the survival of patients with invasive asper-gillosis (IA). However, mortality rates still remain high, possibly influenced by several pitfalls, affecting NCBFDs and reducing the window of opportunity for earlier treatment. A large body of in vitro and in vivo studies has demonstrated that several fungal proteic components are strongly immunogenic, and both the adaptive immunity and the innate branch are heavily involved in the recognition and clearance of fungal pathogens, resulting, on occasion, in a useful tool for the treatment of IA. By evaluating these studies, this review considers the possibility of exploiting either components of the innate or adaptive immunity to support the rapid and early diagnosis of IA.     

Population structure of the South American Estuarine crab, Chasmagnathus granulatus (Brachyura: Varunidae) near the southern limit of its geographical distribution: comparison with northern populations

Crabs are among the most conspicuous and ecologically important invertebrates of the large intertidal zones that characterize estuarine and protected coastal areas in temperate regions. The habitat, population structure and breeding cycle of Chasmagnathus granulatus (Brachyura: Varunidae), a semiterrestrial burrowing crab endemic to the warm temperate coasts of the Southwestern Atlantic, were studied in San Antonio Bay (Argentina), near the southern limit of its range. San Antonio Bay has no freshwater input, winter is relatively colder, and summer warmer, than northern habitats of this species. Crabs lived both in vegetated and unvegetated zones, but density and sex ratio varied among dates and zones. The maximum observed density was 136 crabs/m² , the maximum carapace width (CW) was 32 mm (males) and 29.8 mm (females), ovigerous females were found only in November and January, and the smallest ovigerous female measured 17 mm CW. The population structure, spatial distribution, and recruitment pattern of C. granulatusdid not differ between San Antonio Bay and northern habitats. The higher density, smaller maximum size and shorter reproductive cycle observed in San Antonio cannot be atributed to changes associated with a latitudinal cline and other factors, such as thermal amplitude and food availability, need to be studied.     

Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin

Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance.