Infestation of Rhynchopsyllus pulex (Siphonaptera: Tungidae) on Molossus molossus (Chiroptera) in Southeastern Brazil.

The infestation of Rhynchopsyllus pulex on the bat Molossus molossus was observed using mist-nets opened between constructions in the Primatological Center, in Guapimirim, State of Rio de Janeiro, Brazil.     

A new species of Metadelphis Travassos, 1944 (Digenea: Dicrocoeliidae) from the gall-bladder of Molossus molossus (Pallas) (Chiroptera: Molossidae) in the Brazilian eastern Amazon

Systematic Parasitology - Metadelphis tkachi n. sp. is described based on material from the gall-bladder of Molossus molossus (Pallas) (Chiroptera: Molossidae) in the Brazilian eastern Amazon. The...     

DNA Barcoding Works in Practice but Not in (Neutral) Theory

Background

DNA barcode differences within animal species are usually much less than differences among species, making it generally straightforward to match unknowns to a reference library. Here we aim to better understand the evolutionary mechanisms underlying this usual “barcode gap” pattern. We employ avian barcode libraries to test a central prediction of neutral theory, namely, intraspecific variation equals 2 Nµ, where N is population size and µ is mutations per site per generation. Birds are uniquely suited for this task: they have the best-known species limits, are well represented in barcode libraries, and, most critically, are the only large group with documented census population sizes. In addition, we ask if mitochondrial molecular clock measurements conform to neutral theory prediction of clock rate equals µ.

Results

Intraspecific COI barcode variation was uniformly low regardless of census population size (n = 142 species in 15 families). Apparent outliers reflected lumping of reproductively isolated populations or hybrid lineages. Re-analysis of a published survey of cytochrome b variation in diverse birds (n = 93 species in 39 families) further confirmed uniformly low intraspecific variation. Hybridization/gene flow among species/populations was the main limitation to DNA barcode identification.

Conclusions/Significance

To our knowledge, this is the first large study of animal mitochondrial diversity using actual census population sizes and the first to test outliers for population structure. Our finding of universally low intraspecific variation contradicts a central prediction of neutral theory and is not readily accounted for by commonly proposed ad hoc modifications. We argue that the weight of evidence–low intraspecific variation and the molecular clock–indicates neutral evolution plays a minor role in mitochondrial sequence evolution. As an alternate paradigm consistent with empirical data, we propose extreme purifying selection, including at synonymous sites, limits variation within species and continuous adaptive selection drives the molecular clock.     

Isolation of Salmonella Virchow from a Fruit Bat (Pteropus giganteus)

Detection of zoonotic pathogens carried by bats is important both for understanding disease ecology and for developing preventive measures. Pteropus fruit bats have been identified as potential carriers of Salmonella enterica serotype Typhi. A cross-sectional study was conducted to determine the prevalence of Salmonella Typhi and other Salmonella serotypes in Pteropus giganteus fruit bats in Bangladesh. Rectal swabs were collected from 302 bats and cultured for Salmonella species. The bats were trapped in three districts (Faridpur, Rajbari, and Cox’s Bazar). Salmonella Typhi was not found but one juvenile female bat from Faridpur district was positive for Salmonella Virchow. Close associations between frugivorous bats, humans, and livestock in rural Bangladesh make it likely that the bat was infected by consuming contaminated water.     

Copulation Calls in Female Chimpanzees (<Emphasis Type=Italic>Pan troglodytes schweinfurthii</Emphasis>) Convey Identity but Do Not Accurately Reflect Fertility

Copulation calls are a relatively common feature of female primate behavior thought to function in the advertisement of female receptivity and subsequent incitation of male–male competition. To date, the majority of work on copulation calling behavior has focused on various monkey species, with little empirical evidence from the great apes. Previous research on wild chimpanzees (Pan troglodytes schweinfurthii) has suggested that estrous females produce copulation calls to avoid monopolization by single males and to minimize competition from other females. We here extended these findings by investigating to what degree these social demands were reflected in the calls’ acoustic structure. We recorded and acoustically analyzed 71 copulation call bouts from 6 adult female chimpanzees in the Budongo Forest, Uganda. We did not find any acoustic differences in calls given by females in fertile and nonfertile periods, as assessed by their hormonal profiles. However, the calls’ acoustic structure did reliably encode identity cues of the calling female. We propose that, in chimpanzees, the use and morphology of copulation calls have jointly been shaped by the selective advantage of concealing fertility. Owing to the low visibility conditions associated with chimpanzees’ natural forest habitat and their dispersed social system, providing identity cues may be of particular biological relevance for these nonhuman primates.     

Phytotoxicity of Air Pollutants: Evidence for the Photodetoxification of SO(2) but Not O(3)

Pisum sativum L. cv Alsweet (garden pea) and Lycopersicon esculentum flacca Mill. (tomato) were used to evaluate the phytotoxicity of SO₂ and O₃ in the light and dark. Plants were grown in controlled environment chambers and exposed to SO₂ or O₃ in the light or dark at the same environmental conditions at which they were grown. The pea plants were treated with fusicoccin to ensure open stomata in the dark; the stomata of the tomato mutant remained open in the dark. Both species exhibited 64% to 80% less foliar necrosis following exposure to SO₂ (0.5 to 1.0 microliter per liter for 2 hours) in the light than in the dark. The decrease in SO₂ injury for light versus dark exposed plants was greater in fully expanded than expanding leaves. Both species exhibited 30% greater foliar necrosis following exposure to O₃ (0.2 microliter per liter for 2 hours) in the light than dark. The increase in O₃ injury in the light versus dark was similar for leaves at all stages of expansion. Leaf conductance to water vapor was 7% to 11% and 23% higher in the light than dark for fusicoccin-treated peas and tomato plants, respectively, indicating greater foliar uptake of both pollutants in the light than dark. Thus, the decreased SO₂ toxicity in the light was not associated with pollutant uptake, but rather the metabolism of SO₂. In contrast, the increased toxicity of O₃ in the light was at least in part associated with increased uptake or could not be separated from it.     

Repeated Idazoxan Increases Brain Imidazoline Receptors in Normotensive (WKY) but Not in Hypertensive (SHR) Rats

The specific binding of [3H]idazoxan in the presence of 10(-6) M (-)-adrenaline was used to evaluate the density of imidazoline receptors in the brain of spontaneously hypertensive (SHR) rats and sex- and age-matched normotensive Wistar-Kyoto (WKY) rats. In SHR rats the density of imidazoline receptors (cerebral cortex, hypothalamus, and medulla oblongata) was not different from that in normotensive (WKY) rats. However, repeated treatment with idazoxan consistently increased (23-80%) the density of imidazoline receptors in the various brain regions of WKY rats but not in SHR rats. In normotensive Sprague-Dawley rats, repeated treatment with the imidazoline drugs idazoxan and cirazoline also increased (33-37%) the density of imidazoline receptors in the cerebral cortex. The lack of regulation by idazoxan of the density of imidazoline receptors in the brain of SHR rats might reflect the existence of a relevant abnormality of these receptors in this genetic model of hypertension.     

Guanine Nucleotide Exchange Factors (GEFs) Have a Critical but Not Exclusive Role in Organelle Localization of Rab GTPases

Membrane fusion at eukaryotic organelles is initiated by Rab GTPases and tethering factors. Rabs in their GDP-bound form are kept soluble in the cytoplasm by the GDP dissociation inhibitor (GDI) chaperone. Guanine nucleotide exchange factors (GEFs) are found at organelles and are critical for Rab function. Here, we surveyed the overall role of GEFs in Rab localization. We show that GEFs, but none of the proposed GDI displacement factors, are essential for the correct membrane localization of yeast Rabs. In the absence of the GEF, Rabs lost their primary localization to the target organelle. Several Rabs, such as vacuolar Ypt7, were found at the endoplasmic reticulum and thus were still membrane-bound. Surprisingly, a Ypt7 mutant that undergoes facilitated nucleotide exchange localized to vacuoles independently of its GEF Mon1-Ccz1 and rescued vacuole morphology. In contrast, wild-type Ypt7 required its GEF for localization and to counteract the extraction by GDI. Our data agree with the emerging model that GEFs are critical for Rab localization but raise the possibility that additional factors can contribute to this process.     

Alarm Calls of California Ground Squirrels (Spermophilus beecheyi)

California ground squirrel alarm vocalizations were recorded in field and laboratory, and sonagraphically analysed. The contexts of both naturally occurring and experimentally elicited calls were noted in the field. The components of this graded system are chatters, chats and whistles. Chatters and chats are often elicited by terrestrial predators, whistles commonly by low flying raptors. Whistles are more commonly associated with cryptic behavior and flight than chatter-chats, but both call types usually elicit bipedal alert postures. These calls grade along a number of dimensions which may signal redundantly the level of excitation of the caller. We propose that the chatter-chat calls of highly aroused squirrels are composed of more and longer notes, occur at a higher rate, are less noisy and contain more frequency modulation. Whistles, however, are single-note calls that contain no frequency modulation, even though they are emitted by highly aroused squirrels and are long and noise free. Preliminary data suggest that: 1) chats are easier for a human ♀ to localize than whistles; 2) elevation of the head, by adopting bipedal postures and mounting promontories, enhances the audibility of alarms.     

Phasin Proteins Activate Aeromonas caviae Polyhydroxyalkanoate (PHA) Synthase but Not Ralstonia eutropha PHA Synthase

In this study, we performed in vitro and in vivo activity assays of polyhydroxyalkanoate (PHA) synthases (PhaCs) in the presence of phasin proteins (PhaPs), which revealed that PhaPs are activators of PhaC derived from Aeromonas caviae (PhaC_Ac). In in vitro assays, among the three PhaCs tested, PhaC_Ac was significantly activated when PhaPs were added at the beginning of polymerization (prepolymerization PhaC_Ac), whereas the prepolymerization PhaC_Re (derived from Ralstonia eutropha) and PhaC_Da (Delftia acidovorans) showed reduced activity with PhaPs. The PhaP-activated PhaC_Ac showed a slight shift of substrate preference toward 3-hydroxyhexanoyl-CoA (C₆). PhaP_Ac also activated PhaC_Ac when it was added during polymerization (polymer-elongating PhaC_Ac), while this effect was not observed for PhaC_Re. In an in vivo assay using Escherichia coli TOP10 as the host strain, the effect of PhaP_Ac expression on PHA synthesis by PhaC_Ac or PhaC_Re was examined. As PhaP_Ac expression increased, PHA production was increased by up to 2.3-fold in the PhaC_Ac-expressing strain, whereas it was slightly increased in the PhaC_Re-expressing strain. Taken together, this study provides evidence that PhaPs function as activators for PhaC_Ac both in vitro and in vivo but do not activate PhaC_Re. This activating effect may be attributed to the new role of PhaPs in the polymerization reaction by PhaC_Ac.     

Variation in the Sonar of an Aerial-hawking Bat (Eptesicus nilssonii)

Echolocation calls from 10 individually marked female northern bats (Eptesicus nilssonii) were recorded as the bats foraged at three distinct feeding sites (territories) near their maternity roost in southern Sweden (57° N). In addition, recordings of unmarked bats were made in northern Sweden (65° N). The frequency at maximum amplitude of “search phase” echolocation pulses was bimodally distributed, with peaks around 29–30 kHz and 31–32 kHz and was negatively correlated with pulse duration. The frequency at maximum amplitude was related to flight altitude (bats used higher frequencies when they flew near the ground) and also differed among the feeding sites. Hence, much of the variation, probably including regional differences, was behavioural and is interpreted as short term (in the order of s or min) adaptation to current foraging situations. Variation among individual bats, caused by age and size, seemed to be of less importance. Individuals did not use exclusive frequency bands.     

Evidence for Activation of the Oxidative Pentose Phosphate Pathway during Photosynthetic Assimilation of NO(3) but Not NH(4) by a Green Alga

Addition of NO₃⁻ to N-limited Selenastrum minutum during photosynthesis resulted in an immediate drop in the NADPH/NADP ratio and a slower increase of the NADH/NAD ratio. These changes were accompanied by a rapid decrease in glucose-6-phosphate and increase in 6-phosphogluconate, indicating activation of glucose-6-phosphate dehydrogenase and a role for the oxidation pentose phosphate pathway during photosynthetic NO₃⁻ assimilation. In contrast, the short-term changes in pyridine nucleotides and metabolites during photosynthetic assimilation of NH₄⁺ were not consistent with a stimulation of the oxidative pentose phosphate pathway.     

Emergence,Echolocation, Diet and Foraging Behavior of Molossus ater (Chiroptera: Molossidae)1

Between 4 and 16 January 1996, during a period of cool weather, we studied the emergence and foraging behavior of Molossus ater at a site near Akumal, in the Yucatan Peninsula in Mexico. The bats, a colony of at least 32 individuals, roosted in a north-facing cinder block wall, and emerged about sunset. Emerging bats were usually clustered in time, while those returning usually were not. Radio-tracking revealed that the bats foraged for short periods (mean 26.8 min) and captures of returning individuals indicated that 27 of 28 had fed, taking, on average, 4.4 g of insects, mainly hydrophilid beetles. On some nights, few or none of the radio-tagged bats emerged from the roost. Calculations concerning the costs of flight and roosting show that they were more than covered by the energy intake the bats achieved. Molossus ater have high aspect ratio (8.3–9.1) wings and high wing-loadings of 17.55–24.15 N/m². When searching for prey, these bats produce long (12.3 ms), narrowband(3.8 kHz), echolocation calls that sweep from 27.6–23.8 kHz. Energy was not limiting for these bats at the time of our study.     

Cell Volume Changes Regulate Slick (Slo2.1), but Not Slack (Slo2.2) K+ Channels

Slick (Slo2.1) and Slack (Slo2.2) channels belong to the family of high-conductance K⁺ channels and have been found widely distributed in the CNS. Both channels are activated by Na⁺ and Cl⁻ and, in addition, Slick channels are regulated by ATP. Therefore, the roles of these channels in regulation of cell excitability as well as ion transport processes, like regulation of cell volume, have been hypothesized. It is the aim of this work to evaluate the sensitivity of Slick and Slack channels to small, fast changes in cell volume and to explore mechanisms, which may explain this type of regulation. For this purpose Slick and Slack channels were co-expressed with aquaporin 1 in Xenopus laevis oocytes and cell volume changes of around 5% were induced by exposure to hypotonic or hypertonic media. Whole-cell currents were measured by two electrode voltage clamp. Our results show that Slick channels are dramatically stimulated (196% of control) by cell swelling and inhibited (57% of control) by a decrease in cell volume. In contrast, Slack channels are totally insensitive to similar cell volume changes. The mechanism underlining the strong volume sensitivity of Slick channels needs to be further explored, however we were able to show that it does not depend on an intact actin cytoskeleton, ATP release or vesicle fusion. In conclusion, Slick channels, in contrast to the similar Slack channels, are the only high-conductance K⁺ channels strongly sensitive to small changes in cell volume.     

Recombinant p35 from Bacteria Can Form Interleukin (IL-)12, but Not IL-35

The Interleukin (IL)-12 family contains several heterodimeric composite cytokines which share subunits among each other. IL-12 consists of the subunits p40 (shared with IL-23) and p35. p35 is shared with the composite cytokine IL-35 which comprises of the p35/EBI3 heterodimer (EBI3 shared with IL-27). IL-35 signals via homo- or heterodimers of IL-12Rβ2, gp130 and WSX-1, which are shared with IL-12 and IL-27 receptor complexes, respectively. p35 was efficiently secreted in complex with p40 as IL-12 but not with EBI3 as IL-35 in several transfected cell lines tested which complicates the analysis of IL-35 signal transduction. p35 and p40 but not p35 and EBI3 form an inter-chain disulfide bridge. Mutation of the responsible cysteine residue (p40_C197A) reduced IL-12 formation and activity only slightly. Importantly, the p40_C197A mutation prevented the formation of antagonistic p40 homodimers which enabled the in vitro reconstitution of biologically active IL-12 with p35 produced in bacteria (p35_bac). Reconstitution of IL-35 with p35_bac and EBI3 did, however, fail to induce signal transduction in Ba/F3 cells expressing IL-12Rβ2 and gp130. In summary, we describe the in vitro reconstitution of IL-12, but fail to produce recombinant IL-35 by this novel approach.