Two amphibian diseases, chytridiomycosis and ranaviral disease, are now globally notifiable to the World Organization for Animal Health (OIE): an assessment

The global trade in amphibians entails the transport of tens of millions of live animals each year. In addition to the impact harvesting wild animals can have on amphibian populations, there is mounting evidence that the emerging pathogens Batrachochytrium dendrobatidis and ranaviruses, the aetiological agents of chytridiomycosis and ranaviral disease, respectively, are spread through this trade. The link between these pathogens and amphibian declines and extinctions suggests that the epidemiological impact of the trade is significant and may negatively affect conservation and trade economics. Here we present a brief assessment of the volume of the global trade in live amphibians, the risk of individuals harboring infection, and information on the recent listing by the World Organization for Animal Health (OIE) of chytridiomycosis and ranaviral disease in the OIE Aquatic Animal Health Code. This listing made chytridiomycosis and ranaviral disease internationally notifiable diseases and thus subject to OIE standards, which aim to assure the sanitary safety of international trade in live amphibians and their products.     

Inhibitors of HIV-1 attachment. Part 4: A study of the effect of piperazine substitution patterns on antiviral potency in the context of indole-based derivatives

4-Fluoro- and 4-methoxy-1-(4-benzoylpiperazin-1-yl)-2-(1H-indol-3-yl)ethane-1,2-dione (2 and 3, respectively) have been characterized as potent inhibitors of HIV-1 attachment that interfere with the interaction of viral gp120 with the host cell receptor CD4. As part of an effort to understand fundamental aspects of this pharmacophore, discovered originally using a high throughput cell-based screen, modification and substitution of the piperazine ring was examined in the context of compounds 6a–ah. The piperazine ring was shown to be a critical element of the HIV-1 attachment inhibiting pharmacophore, acting as a scaffold to deploy the indole glyoxamide and benzamide in a topographical relationship that complements the binding site on gp120.     

The secretion antigen SA5K has a role in the adaptation of Mycobacterium bovis bacillus Calmette-Guérin to intracellular stress and hypoxia

The Mycobacterium tuberculosis TB8.4 (Rv1174c) gene encodes a secreted protein of 8.4 kDa (TB8.4) which has been suggested to be involved in reactivation of dormant mycobacteria. We have previously reported that inactivation of an identical gene (sa5k) in Mycobacterium bovis BCG causes impaired ability of the mutant strain (BCGsa5k::aph) to grow inside human macrophages. This study aimed to investigate the role of TB8.4 in the reactivation of aged cultures of BCG as well as the role of the sa5k gene in the resistance of BCG to intracellular stress conditions and adaptation to hypoxia. Although when added to aged cultures of BCG, TB8.4 caused a statistically significant increase in the number of colony-forming units, a similar effect was obtained in cultures incubated with BSA, suggesting a non-specific growth stimulation by TB8.4. Compared to parental BCG, the BCGsa5k::aph strain showed an increased susceptibility to reactive oxygen and nitrogen intermediates and to acid stress and an impaired ability to adapt to reduced O2 concentrations, when tested in the oxygen-limited Wayne culture system. These results suggest that the product of the sa5k gene (SA5K protein) has a role in both resistance of BCG to intracellular stress and in its adaptation to hypoxia.     

The Decline of the Sharp-Snouted Day Frog (Taudactylus acutirostris): The First Documented Case of Extinction by Infection in a Free-Ranging Wildlife Species?

Infectious diseases are increasingly recognized as the cause of mass mortality events, population declines, and the local extirpation of wildlife species. In a number of cases, it has been hypothesized that pathogens have caused species extinctions in wildlife. However, there is only one definitively proven case of extinction by infection, and this was in a remnant captive population of a Polynesian tree snail. In this article, we review the potential involvement of infectious disease in the recent extinction of the sharp-snouted day frog Taudactylus acutirostris. Our review of available evidence suggests that a virulent pathogen of amphibians, Batrachochytrium dendrobatidis, caused a rapid, catastrophic decline of this species, from which it did not recover. We propose that this is the first case of extinction by infection of a free-ranging wildlife species where disease acted as both the proximate and ultimate cause of extinction. This highlights a probable underreporting of infectious disease as a cause of biodiversity loss historically and currently.     

Generation and maintenance of diversity in the cattle MHC class I region

Major histocompatibility complex (MHC) class I genes play a crucial role in the immune defence against intracellular pathogens. An important evolutionary strategy is to generate and maintain a high level of diversity in these genes. Humans express three highly polymorphic classical MHC class I genes (HLA-A, HLA-B and HLA-C). In contrast, some species, for example rat and rhesus macaque, maintain diversity by generation of haplotypes that vary considerably with regard to the number and combination of transcribed genes. Cattle appear to use both strategies. We show that various combinations of six apparently classical genes, three of which are highly polymorphic, are transcribed on different haplotypes. Although additional sequences were identified in both cDNA and gDNA, it was not possible to assign them to any of these defined genes. Most were highly divergent or were non-classical class I genes. Thus, we found little evidence for frequent duplication and deletion of classical class I genes as reported in some other species. However, the maintenance of class I diversity in cattle may involve limited gene shuffling and deletion, possibly as a result of unequal crossing-over within the class I region.The first two authors made an equal contribution to this work.     

Differences between arterial and mixed venous levels of plasma hydroperoxides following major thoracic and abdominal operations

Fatty acid hydroperoxides in the plasma of 18 patients who were undergoing normal postoperative periods following major thoracic or abdominal operations were measured by using a sensitive assay based upon the activation of the cyclooxygenase activity of prostaglandin H synthase. Following major thoracic operations of nine patients, the mean difference between the arterial (0.49 ± 0.13 μM, mean ± S.E.M.) and mixed venous (−0.09 ± 0.12 μM) level of hydroperoxide was 0.58 ± 0.13 μM (p < 0.01). In marked contrast to this result, major abdominal operations of nine patients led to a mean difference between the arterial (−0.19 ± 0.16 μM) and mixed venous (0.46 ± 0.08 μM) hydroperoxide levels of −0.65 ± 0.17 μM (p < 0.01). Both pulmonary and intraabdominal tissues appear capable of generating significant amounts of fatty acid hydroperoxide in response to standard surgical procedures. The A-MV differences suggest that the blood-borne hydroperoxides were rapidly cleared from the circulation by tissue capillary beds.     

FISH studies of the sperm of fathers of paternally derived cases of trisomy 21: no evidence for an increase in aneuploidy

Paternal nondisjunction accounts for approximately 5% of cases of trisomy 21. To test the hypothesis that, in some such cases, the fathers might be predisposed to meiotic nondisjunction, we utilized fluorescence in situ hybridization (FISH) to screen for aneuploidy in sperm. We analyzed sperm samples from ten males with a trisomy 21 offspring of paternal origin. Among these individuals, the overall frequency of disomy 21 was 0.15%, comparable to estimates of disomy 21 in the general male population. Furthermore, none of the ten fathers of trisomy 21 individuals had significantly elevated levels of disomic sperm. Thus, our results provide no evidence that the occurrence of a trisomy 21 conceptus of paternal origin imparts an increased risk of trisomy in subsequent pregnancies. Received: 9 September 1998 / Accepted: 30 September 1998     

Male competition reverses female preference for male chemical cues

Females must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses that fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. In Bolitotherus cornutus (forked fungus beetles), males compete for access to females, but copulation requires female cooperation. In this study, we use behavioral trials to determine whether females use chemical cues to differentiate between males and whether the outcome of recent male competition alters female preference. We measured female association time with chemical cues of two size‐matched males both before and after male–male competition. Females in our study preferred to associate with future losers before males interacted, but changed their preference for realized winners following male competitive interactions. Our study provides the first evidence of change in female preference based solely on the outcome of male–male competition.