RESUMO

Blood-O2 affinities (P50 ) were measured over a physiologically relevant pH range at 31 (highest temperature average of Rio Negro over the last 8 years), 33 and 35° C for 10 species of the Rio Negro, aiming to test the acute effects of temperature foreseen by the IPCC (Intergovernmental Panel on Climate Change) for coming years. The animals were collected during an expedition to the Anavilhanas Islands of the Rio Negro, 110 km upstream from Manaus (2° 23' 41″ S; 60° 55' 14″ W). Hoplias malabaricus showed higher blood-O2 sensitivity to pH changes (Bohr effect, Φ = Δlog10 P50 ΔpH(-1) ) at both 31° C (Φ = -0·44) and 35° C (Φ = -0·26) compared to Osteoglossum bicirrhosum (Φ = -0·54 at 31° C and Φ = -0·58 at 35° C), but lower P50 under most conditions, and a greater sensitivity of P50 to temperature. Two out of the 10 analysed species had significant increases of P50 (lower blood-O2 affinity) at the highest temperature throughout the pH range tested. For all other species, a minor increase of P50 over the assay-tested temperatures was observed, although all presented a normal Bohr effect. Overall, a diversity of intensities of pH and temperature effects on blood-O2 affinities was observed, which seems to be connected to the biological characteristics of the analysed species. Thermal disturbances in their habitats, likely to occur due to the global warming, would impair blood-O2 binding and unloading in some of the analysed fish species. Copyright © 2016 John Wiley & Sons, Ltd.

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Sperm motility, crucial for fertilization, has been mostly studied in two dimensions (2D) by recording their swimming trajectories near a flat surface. However, spermatozoa swim in three-dimensions (3D) to find eggs, with their speed being the main impediment to track them under realistic conditions. Here, we describe a novel method allowing 3D tracking and analysis of the trajectories of multiple free-swimming sperm. The system uses a piezo-electric device displacing a large focal distance objective mounted on a microscope to acquire 70 image stacks per second, each stack composed of 60 images that span a depth of 100 microm. With this method, 3D paths of multiple sperm in the same field could be visualized simultaneously during 1 s. Within the same sample we found that surface-confined sperm swam 25% slower, produced 3-fold fewer circular revolutions per second, and had trajectories of 134% greater radius of curvature than those sperm swimming freely in 3D.

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The effects of elevated dietary calcium (as CaCO3) and acute waterborne Cd exposure (50 microg/l) on whole body uptake, tissue uptake, and internal distribution of newly accumulated Cd, Ca2+, and Na+ in juvenile rainbow trout were examined. Fish were fed with three diets (mg Ca2+/g food): 20 (control), 30 and 60 for 7 days before fluxes were measured with radiotracers. The highest dietary Ca2+ elevation reduced waterborne whole body Ca2+ uptake, but did not protect against inhibition of waterborne Ca2+ uptake by waterborne Cd. Both Ca2+-supplemented diets reduced newly accumulated Ca2+ in the gills in relation to the control treatment, but did not prevent the Cd-inhibiting effect against accumulation of new Ca2+ in most compartments. Fish fed with Ca2+-supplemented diets showed markedly lower rates of whole body uptake and internalization (in some tissues) of waterborne Cd, illustrating that, while dietary Ca2+ supplementation did not protect against the impact of waterborne Cd on waterborne Ca2+ uptake, it did protect against the uptake of Cd. Waterborne Cd had no effect on Na+ fluxes, total Cl-, and in most body compartments, newly accumulated Na+ and total Na+ were also not affected. Dietary supplementation with CaCO3 had the same protective effect as demonstrated by dietary supplementation with CaCl2 in an earlier study. Thus, the reduction of waterborne Cd uptake and internalization by dietary Ca2+ was specifically due to Ca2+ and not to the anion.

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The present study examined the interactions between elevated dietary calcium (as ionic Ca2+ in the form of CaCl2 x 2H2O) and acute waterborne Cd exposure (50 microg/l as CdNO3 for 3 h) on whole body uptake and internal distribution of newly accumulated Cd, Ca2+, and Na+ in juvenile rainbow trout (Oncorhynchus mykiss). Fish were fed with three diets 20 (control), 30 and 60 mg Ca2+/g food: for 7 days before fluxes were measured with radiotracers over a 3h period. The two elevated Ca2+ diets reduced the whole body uptake of both Ca2+ and Cd by >50% and similarly reduced the internalization of both newly accumulated metals in most tissues, effects which reflect the shared branchial uptake route for Ca2+ and Cd. As the Ca2+ concentrations of the fluid phases of the stomach and intestinal contents were greatly elevated by the experimental diets, increased gastrointestinal Ca2+ uptake likely caused the down-regulation of the branchial Ca2+ (and Cd) uptake pathway. Waterborne Na+ uptake and internal distribution were not affected. While plasma Ca2+ surged after the first two feedings of the 60 mg Ca2+/g diet, internal homeostasis was quickly restored. Total Ca2+, Na+, and Cl- levels in tissues were not affected by diets. While dietary Ca2+ protected against waterborne Cd uptake, it did not protect against the relative inhibition of waterborne Ca2+ uptake caused by waterborne Cd. Acute exposure to 50 microg/l Cd reduced the uptake and internalization of newly accumulated Ca2+ (but not Na+) by 70% or more, regardless of diet. Since elevated dietary Ca2+ reduces waterborne Cd uptake, fish eating a Ca(2+)-rich invertebrate diet may be more protected against waterborne Cd toxicity in a field situation.

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Two months after starting highly active antiretroviral treatment (HAART), an individual with human immunodeficiency virus type 1 (HIV-1) infection and profound CD4+ T lymphocytopenia developed several erythematous plaques on his face, which were due to borderline tuberculoid leprosy with reversal reaction. The temporal association between the development of these lesions and changes in blood CD4+ lymphocyte count and plasma HIV-1 load observed during HAART strongly suggests that the presentation of leprosy resulted from immune reconstitution.

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We measured unidirectional ion fluxes of fish collected directly from the Rio Negro, an extremely dilute, acidic blackwater tributary of the Amazon. Kinetic analysis of Na(+) uptake revealed that most species had fairly similar J(max) values, ranging from 1,150 to 1,750 nmol g(-1) h(-1), while K(m) values varied to a greater extent. Three species had K(m) values <33 micromol L(-1), while the rest had K(m) values >or=110 micromol L(-1). Because of the extremely low Na(+) concentration of Rio Negro water, the differences in K(m) values yield very different rates of Na(+) uptake. However, regardless of the rate of Na(+) uptake, measurements of Na(+) efflux show that Na(+) balance was maintained at very low Na(+) levels (<50 micromol L(-1)) by most species. Unlike other species with high K(m) values, the catfish Corydoras julii maintained high rates of Na(+) uptake in dilute waters by having a J(max) value at least 100% higher than the other species. Corydoras julii also demonstrated the ability to modulate kinetic parameters in response to changes in water chemistry. After 2 wk in 2 mmol L(-1) NaCl, J(max) fell >50%, and K(m) dropped about 70%. The unusual acclimatory drop in K(m) may represent a mechanism to ensure high rates of Na(+) uptake on return to dilute water. As well as being tolerant of extremely dilute waters, Rio Negro fish generally were fairly tolerant of low pH. Still, there were significant differences in sensitivity to pH among the species on the basis of degree of stimulation of Na(+) efflux at low pH. There were also differences in sensitivity to low pH of Na(+) uptake, and two species maintained significant rates of uptake even at pH 3.5. When fish were exposed to low pH in Rio Negro water instead of deionized water (with the same concentrations of major ions), the effects of low pH were reduced. This suggests that high concentrations of dissolved organic molecules in the water, which give it its dark tea color, may interact with the branchial epithelium in some protective manner.

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Human Herpes virus type-8 (HHV-8) seroprevalence was studied in a population of HIV positive intravenous drug users (IVDUs) from Argentina. Analysis of this population also indirectly made it possible to study HHV-8 blood transmission, because these individuals frequently engage in needle sharing behavior and are capable of acquiring a broad array of blood borne pathogens, including Hepatitis B/C virus. The seroprevalence of HHV-8 in IVDUs was compared to a group of non-IVDUs and HIV negative individuals. Of the 223 individuals tested, 13.45% were HHV-8 positive, 16.99% in the IVDUs group, and 5.71% in the non-IVDUs. Among HIV positive IVDUs, 25/144 (17.36%) were also HHV-8 seropositive. The seropositivity rate of HHV-8 in HIV negative IVDUs was 11.1%. In contrast, HHV-8 seroprevalence in HIV negative heterosexual individuals without drug usage behavior was even lower (5.71%). The rate of HHV-8 infection in HIV positive IVDUs was three times as high compared to the non IVDU HIV negative individuals, suggesting that IVDU is a risk for HHV-8 infection. Furthermore, it was found that IVDUs showed a very high rate of Hepatitis B/C (52.77%), which also correlate with HHV-8 infection in this population (23.68%). All Hepatitis B/C positive individuals were also HIV positive. Our data confirm other studies showing that individuals who share needles are at risk for acquiring Hepatitis B/C and HIV infections. In addition, our results suggest that they are also at risk to acquiring HHV-8 infection by the same route.

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Human Herpes virus type-8 (HHV-8) seroprevalence was studied in a population of HIV positive intravenous drug users (IVDUs) from Argentina. Analysis of this population also indirectly made it possible to study HHV-8 blood transmission, because these individuals frequently engage in needle sharing behavior and are capable of acquiring a broad array of blood borne pathogens, including Hepatitis B/C virus. The seroprevalence of HHV-8 in IVDUs was compared to a group of non-IVDUs and HIV negative individuals. Of the 223 individuals tested, 13.45

were HHV-8 positive, 16.99

in the IVDUs group, and 5.71

in the non-IVDUs. Among HIV positive IVDUs, 25/144 (17.36

) were also HHV-8 seropositive. The seropositivity rate of HHV-8 in HIV negative IVDUs was 11.1

. In contrast, HHV-8 seroprevalence in HIV negative heterosexual individuals without drug usage behavior was even lower (5.71

). The rate of HHV-8 infection in HIV positive IVDUs was three times as high compared to the non IVDU HIV negative individuals, suggesting that IVDU is a risk for HHV-8 infection. Furthermore, it was found that IVDUs showed a very high rate of Hepatitis B/C (52.77

), which also correlate with HHV-8 infection in this population (23.68

). All Hepatitis B/C positive individuals were also HIV positive. Our data confirm other studies showing that individuals who share needles are at risk for acquiring Hepatitis B/C and HIV infections. In addition, our results suggest that they are also at risk to acquiring HHV-8 infection by the same route.

RESUMO

Sensitivity to acid water was assessed in three species of Amazonian fish that encounter naturally acidic blackwaters to differing degrees in the wild: tambaqui (Colossoma macropomum), matrincha (Brycon erythropterum), and tamoatá (Hoplosternum littorale), in decreasing order of occurrence in blackwater. Fish were exposed to a graded reduction in water pH, from pH 6 to 5 to 4 to 3.5, followed by return to pH 6. Fish were exposed to each new pH for 24 h. During these exposures, net transfers of ions (Na+, K+, Cl-, and Ca2+) and acid-base equivalents to and from the external water were used as physiological indicators of acid tolerance. Exposure to pH 5 had a minimal effect on net ion fluxes. Significant net losses of all ions (except Ca2+) were recorded in all three species during the first few hours of exposure to pH 4. However, ion balance was usually restored within 18 h at pH 4. Exposure to pH 3.5 caused even greater ion losses in all three species and proved to be acutely lethal to tamoatá. Matrincha sustained irreversible physiological damage at pH 3.5, as ion fluxes did not recover following return to pH 6 and there was some mortality. Tambaqui suffered the least ionoregulatory disturbances at pH 3.5 and was the only species to make a full recovery on return to pH 6. In all species, there was a tendency for ammonia excretion to increase at low water pH, but even at pH 3.5, there was no significant net uptake of acid from the water. Overall, there was a strong relationship between the magnitude of ionic disturbances and the lethality of exposure to low pH. The relative insensitivity of the ionoregulatory system of tambaqui to low pH indicates that this is a feature of fish native to blackwater systems rather than one that is common to all Amazon fish.

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RESUMO

Our goal was to compare the internal physiological responses to acid challenge in an acidophilic tropical teleost endemic to dilute low-pH waters with those in nonacidophilic temperate species such as salmonids, which have been the subjects of most previous investigations. The Amazonian tambaqui (Colossoma macropomum), which migrates between circumneutral water and dilute acidic "blackwater" of the Rio Negro, was exposed to a graded low-pH and recovery regime in representative soft water (Na+ = 15, Cl- = 16, Ca2+ = 20 mumol L-1). Fish were fitted with arterial catheters for repetitive blood sampling. Water pH was altered from 6.5 (control) to 5.0, 4.0, 3.0, and back to 6.5 (recovery) on successive days. Some deaths occurred at pH 3.0. Throughout the regime, there were no disturbances of blood gases (O2 and CO2 tensions and contents) or lactate levels, and only very minor changes in acid-base status of plasma and red cells. However, erythrocytic guanylate and adenylate levels increased at pH's less than or equal to 5.0. Down to pH 4.0, plasma glucose, cortisol, and total ammonia levels remained constant, but all increased at pH 3.0, denoting a stress response. Plasma Na+ and Cl- levels declined and plasma protein concentration increased at pH 3.0, indicative of ionoregulatory and fluid volume disturbance, and neither recovered upon return to pH 6.5. Cortisol and ammonia elevations also persisted. Transepithelial potential changed progressively from highly negative values (inside) at pH 6.5 to highly positive values at pH 3.0; these alterations were fully reversible. Experimental elevations in water calcium levels drove the transepithelial potential positive at circumneutral pH, attenuated or prevented changes in transepithelial potential at low pH, and reduced Na+ and Cl- loss rates to the water during acute low-pH challenges. In general, tambaqui exhibited responses to low pH that were qualitatively similar but quantitatively more resistant than those previously documented in salmonids.

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