High temporal and individual variation in the prevalence and intensity of chytrid infection in the southernmost Leaf Frog of the genus Pithecopus (Anura,Phyllomedusidae)

Hydrobiologia - Pithecopus rusticus is an endemic amphibian restricted to the type locality, in southern Brazil, and possibly endangered to extinction, due to habitat degradation. However, an...     

Social effects on fruit fly courtship song

Courtship behavior in Drosophila has often been described as a classic innate behavioral repertoire, but more recently extensive plasticity has been described. In particular, prior exposure to acoustic signals of con‐ or heterspecific males can change courtship traits in both sexes that are liable to be important in reproductive isolation. However, it is unknown whether male courtship song itself is socially plastic. We examined courtship song plasticity of two species in the Drosophila melanogaster subgroup. Sexual isolation between the species is influenced by two male song traits, the interpulse interval (IPI) and sinesong frequency (SSF). Neither of these showed plasticity when males had prior experience of con‐ and heterospecific social partners. However, males of both species produced longer bursts of song during courtship when they were exposed to social partners (either con‐ or heterospecific) than when they were reared in isolation. D. melanogaster carrying mutations affecting short‐ or medium‐term memory showed a similar response to the social environment, not supporting a role for learning. Our results demonstrate that the amount of song a male produces during courtship is plastic depending on the social environment, which might reflect the advantage of being able to respond to variation in intrasexual competition, but that song structure itself is relatively inflexible, perhaps due to strong selection against hybridization.     

A homologue of Drosophila aurora kinase is oncogenic and amplified in human colorectal cancers.

Genetic and biochemical studies in lower eukaryotes have identified several proteins that ensure accurate segregation of chromosomes. These include the Drosophila aurora and yeast Ipl1 kinases that are required for centrosome maturation and chromosome segregation. We have identified two human homologues of these genes, termed aurora1 and aurora2, that encode cell-cycle-regulated serine/threonine kinases. Here we demonstrate that the aurora2 gene maps to chromosome 20q13, a region amplified in a variety of human cancers, including a significant number of colorectal malignancies. We propose that aurora2 may be a target of this amplicon since its DNA is amplified and its RNA overexpressed, in more than 50% of primary colorectal cancers. Furthermore, overexpression of aurora2 transforms rodent fibroblasts. These observations implicate aurora2 as a potential oncogene in many colon, breast and other solid tumors, and identify centrosome-associated proteins as novel targets for cancer therapy.     

Citizen science and observer variability during American pika surveys

Within- and between-group observer variability can confound scientific discovery. If observer variability can be quantified and is addressed, data collected by participants with wide ranges of experience and training can yield more reliable inferences. The American pika (Ochotona princeps) is a mammalian sentinel of climate change that has received consideration for listing under the United States Endangered Species Act. As a result, numerous pika monitoring initiatives have been started throughout the mountains in western North America. Some initiatives employ research teams of biological science technicians (professionals), whereas many rely on networks of citizen scientists, or volunteers, for data collection. To date, few studies have quantified observer variability during pika surveys; none have explored the reliability of professional crews or volunteers. We conducted pika surveys in Glacier National Park, Montana, to quantify observer variability. We investigated observer variability 1) among a crew of professionals, 2) among volunteers, and 3) between professionals and volunteers. Professionals were more consistent at identifying pika signs and estimating potential home ranges and consistently found more pika signs than did the volunteers, with the exception of pika sightings. Estimates of pika occupancy were consistent at each site among volunteers conducting sitting surveys. We suggest that sitting surveys conducted by volunteers can reliably detect pika site occupancy. However, data on population dynamics of pikas (e.g., density) should be collected by professionals. Observer variability analyses of this nature should be common practice for wildlife-resource managers and scientists, especially with observers of varying levels of experience and motivation. © 2012 The Wildlife Society.     

Carolina Chickadee (Aves, Paridae, Poecile carolinensis) Vocalization Rates: Effects of Body Mass and Food Availability under Aviary Conditions

We evaluated the effect of body mass and several environmental factors on vocalization rates of Carolina chickadees ( Poecile carolinensis ) housed in an aviary. Two different nonsong vocalizations (tseet and chick-a-dee) and song (fee-bee fee-bay) were recorded. Food was delivered from a feeder and three different levels of food access were presented to each bird: 10, 40 and 55 min/d. Two scales of body mass were measured: 'dawn mass' and 'focal mass' (mass during a focal observation divided by dawn mass). Across all birds, there was a significant negative correlation between both nonsong vocalization rates and body mass (both dawn and focal mass) and the effect of mass on call rate was greatest for days when food was relatively abundant. Nonsong vocalizations were also given at higher rates when food was limited (10 min/d) than when food was more abundant (40 and 55 min/d). No changes in call rates with time of day were observed. Overall, song rates were substantially lower than nonsong rates. Unlike nonsong rates, song rates were highest in birds that had relatively high dawn mass. No significant correlation between song rates and focal mass was observed, and no significant correlation between song rates and time of day was observed. Finally, vocalizations from nonfocal birds had little effect on vocalization rates of focal birds. Our results suggest that nonsong communicative signals are more important for birds facing energetic stress, while song is more important for birds that are not energetically stressed.     

Cytotoxic activity of lymphocytes. VI. Heterogeneity of cytotoxins in supernatants of mitogen-activated lymphocytes.

Two different lymphotoxins synthesized by human blood lymphocytes stimulated with phytohemagglutin (PHA) are described. The two toxins are called alpha-LT and beta-LT relative to their elution order on gel chromatography. Their m.w. are 75,000 and 45,000 daltons, respectively. Both toxins appear as early as 7 hr after the addition of PHA, with the amount of beta-toxin exceeding that of alpha-LT initially. Both toxins are differentiated from a third toxin (adherent cell toxin, ACT) made by plastic-adherent cells without requiring mitogen-stimulation. Depletion of macrophages or B cells does not affect the synthesis of either lymphotoxin. Monospecific antisera were elicited to alpha-LT. Antisera elicited to beta-LT also neutralized alpha-LT but to a significantly lesser degree. Alpha-LT appears to be the lymphotoxin described by most other workers. Beta-LT is unstable at 37 degrees C which may explain why the low m.w. lymphotoxin has not been described previously.     

Purification, characterization, and cloning of a serine proteinase inhibitor from the ectoparasite Haematobia irritans irritans (Diptera: Muscidae)

The fly Haematobia irritans irritans is one of the most important ectoparasites in cattle production, due to its ability to suck large amounts of blood. This report describes the purification and characterization of a serine proteinase inhibitor (HiTI) present in H. i. irritans head and thorax extracts. The HiTI purified by affinity chromatography on trypsin-Sepharose has a molecular mass of 7029Da by MALDI-TOF mass spectrometry. HiTI inhibited bovine trypsin, human neutrophil elastase, and a trypsin-like enzyme purified from H. i. irritans abdomen with dissociation constants of 0.57, 1.30, and 0.20nM, respectively. The HiTI partial amino acid sequence allowed its classification into the BPTI-Kunitz-type family. An HiTI cDNA fragment was cloned in the pGEMT vector using RT-PCR. The translated amino acid sequence of HiTI cDNA confirmed a unique Kunitz-type-domain protein. Our results suggest that HiTI could control some endogenous enzyme, e.g., the H. i. irritans trypsin-like protein.