RNA of Australia Antigen

ALTHOUGH the exact nature of Australia (Au) antigen is not resolved, increasing evidence suggests that it is the causal agent of viral hepatitis. This supposition is based chiefly on the frequent occurrence of Au antigen in the sera of patients with viral hepatitis^1–4 and on its virus-like appearance under the electron microscope^5–7. Biochemical studies have shown that Au antigen consists largely of protein, with a minor lipid moiety^{8, 9}. So far, however, no genetic material has been detected in the Au antigen and it has been suggested that the Au antigen might be “a unique infectious particle with little or no nucleic acid”¹⁰. We wish to present evidence, however, that RNA is an essential component of Au antigen.     

Composition of Mammalian Eumelanins: Analyses of DHICA-Derived Units in Pigments From Hair and Melanoma Cells

The proportions in which two eumelanin monomers, namely 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and 5,6-dihydroxyindole (DHI), compose the eumelanin polymer are believed to determine properties of the pigment including its color. These proportions are, however, not well elucidated for naturally occurring eumelanins, largely because of methodological difficulties. In this study we estimate the content of DHICA-derived units in mammalian eumelanins using a combination of two analytical techniques: 1) quantitation of DHICA-derived eumelanin by measuring the yield of pyrrole-2,3,5-tricarboxylic acid (PTCA index) and 2) spectrophotometrical quantitation of total (DHI + DHICA) eumelanin at 350 nm (A₃₅₀ index). The ratio of PTCA/A₃₅₀ measured for melanins synthesized from DHI and DHICA mixed in various molar proportions correlates well with the content of DHICA in synthetic polymers. Using this relationship as a standard curve we estimated the proportion of DHICA-derived units in mammalian eumelanins from hair and melanoma cells and found it to be much higher in rodent pigments (58.8%-98.3%; two species, mouse and hamster were examined) as compared to human eumelanins (19.2%-41.8%; one Caucasian and one Oriental individual were examined). No relationship between proportion of DHICA-derived units in eumelanin and hair color is found. The latter seems to be determined predominantly by the ratio of pheo- to eumelanin synthesis.     

Characterization of 14 polymorphic microsatellite markers for the black‐tailed prairie dog (Cynomys ludovicianus)

We report the development of 14 polymorphic microsatellite markers for the black‐tailed prairie dog, Cynomys ludovicianus. The number of alleles per locus ranges from three to 11, and the observed heterozygosity ranges from 0.37500 to 1.0000. These markers will benefit studies of landscape effects on prairie dog migration, disease dynamics, and conservation efforts.     

Foot-thumping as an alarm signal in macropodoid marsupials: prevalence and hypotheses of function

• 1 Alarm signalling as a means to reduce predation risk is an important component of the behavioural repertoire of many species. It has previously been noted that many of the macropodoid marsupials (kangaroos, wallabies and rat‐kangaroos) produce a foot‐thump, an audible signal created by striking the ground with one or both feet, that is most likely an alarm signal.
• 2 The prevalence of foot‐thumping within the macropodoids and hypotheses of its function as an alarm signal have been poorly documented. To address this issue, we investigate the prevalence of foot‐thumping in macropodoids and interpret possible function according to current alarm signalling theory. Evidence for foot‐thumping was found in almost all macropodoids. In light of this, the behaviour appears to be a conservative trait that may have arisen alongside or followed the evolution of bipedal locomotion, and suggests that this trait carries significant benefits that transcend ecological and predation differences among species.
• 3 Nine alarm signal hypotheses were explored in order to determine the function of foot‐thumping in macropodoid marsupials. However, the existing evidence for consistent function remains inconclusive. Therefore, a series of predictions were developed to provide the foundation for future research to investigate more thoroughly the function of foot‐thumping in macropodoid marsupials.

     

Analysis of a Repeat-Containing Family of Giardia lamblia Variant-Specific Surface Protein Genes: Diversity Through Gene Duplication and Divergence

ABSTRACT. Giardia lamblia trophozoites express on their surfaces one of a set of cysteine-rich antigenically variant proteins, called variant-specific surface proteins, which comprise the majority of proteins detected by surface labeling. While these VSP proteins may be immunodominant proteins important in the host immune response to G. lamblia , the ability to switch expression from one VSP to another may provide a means for the trophozoites to avoid the host immune response. The first VSP characterized, VSPA6 (from the A6 clone of the WB isolate, originally termed CRP170), contains 18–23 copies of a 65 amino acid repeat. We have now used the repeat as a probe to isolate from a WBA6 genomic library two genes related to vspA6 (called vspA6-S1, vspA6-S2). Sequence analysis of the vspA6-S1 gene revealed nearly two complete copies of the 195 bp repeat and substantial nucleotide and translated amino acid similarity in the coding regions 5'and 3'to the repeats. The vspA6-S2 gene, while still related, showed greater divergence from vspA6 than vspA6-S1 in the nonrepeat coding region and contained nearly four copies of a 201 bp repeat that was 75% identical to the 195 bp vspA6 repeat. These results suggest that gene duplication followed by divergence has played a key role in the generation of the vsp gene repertoire.     

Phylogeny and evolution of phytophagous ladybird beetles (Coleoptera: Coccinellidae: Epilachnini), with recognition of new genera

Phytophagous ladybird beetles of the tribe Epilachnini are a cosmopolitan, species‐rich group of significant economic importance as pests of agricultural crops. The tribe is well characterized morphologically and clearly monophyletic, but very little is known about its internal phylogenetic relationships and their genus‐level taxonomy. In order to infer the evolutionary history of Epilachnini, test its monophyly and provide a phylogeny‐based classification, we assembled a comprehensive dataset, consisting of four DNA markers (18S and 28S rRNA and 16S, COI mtDNA) and a matrix of 104 morphological characters for 153 species of Epilachnini representing all previously recognised genera, ～11% of the known species, and 14 outgroup taxa. Molecular, morphological and combined datasets were analysed using maximum likelihood, parsimony and Bayesian inference. Bayes factors and Approximately Unbiased tests (AU) were used to compare alternative phylogenetic hypotheses of unconstrained and backbone‐constrained analysis. Only 14 of the 25 included genera were recovered monophyletic, as originally defined. Afidentula Kapur, Afidenta Dieke, Afissula Kapur, Epilachna Chevrolat, Henosepilachna Li Toxotoma Weise and Mada Mulsant are shown to be poly‐ or paraphyletic; Chnootriba Chevrolat, Subafissa Bielawski, Lalokia Szawaryn & Tomaszewska and Papuaepilachna Szawaryn & Tomaszewska form monophyletic groups within larger clades of genus level. All of these genera are redefined here. The two largest genera of Epilachnini, Epilachna Chevrolat and Henosepilachna Li were represented by multiple monophyletic clades, which we described as new genera: Chazeauiana Tomaszewska & Szawaryn gen.n. ; Diekeana Tomaszewska & Szawaryn gen.n .; Fuerschia Tomaszewska & Szawaryn gen.n. and Ryszardia Tomaszewska & Szawaryn gen.n . The following new synonyms are proposed: Afissa Dieke (=Afissula Kapur); Henosepilachna Li in Li & Cook (=Subafissa Bielawski); Papuaepilachna Szawaryn & Tomaszewska (=Lalokia Szawaryn & Tomaszewska). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:440E7FA4‐C859‐47E0‐8335‐30D478CBA8FA .     

Patterns of divergence in the olive sunbird Cyanomitra olivacea (Aves: Nectariniidae) across the African rainforest–savanna ecotone

In the debate over modes of vertebrate diversification in tropical rainforests, two competing hypotheses of speciation predominate: those that emphasize the role of geographical isolation during glacial periods and those that stress the role of ecology and diversifying selection across ecotones or environmental gradients. To investigate the relative roles of selection versus isolation in refugia, we contrasted genetic and morphologic divergence of the olive sunbird (Cyanomitra olivacea) at 18 sites (approximately 200 individuals) across the forest–savanna ecotone of Central Africa in a region considered to have harboured three hypothesized refugia during glacial periods. Habitats were characterized using bioclimatic and satellite remote‐sensing data. We found relatively high levels of gene flow between ecotone and forest populations and between refugia. Consistent with a pattern of divergence‐with‐gene‐flow, we found morphological characters to be significantly divergent across the gradient [forest versus ecotone (mean ± SD): wing length 60.47 ± 1.81 mm versus 62.18 ± 1.35 mm; tarsus length 15.51 ± 0.82 mm versus 16.00 ± 0.57 mm; upper mandible length 21.77 ± 1.09 mm versus 23.19 ± 0.98 mm, respectively]. Within‐habitat comparisons across forest and ecotone sites showed no significant differences in morphology. The results show that divergence in morphological traits is tied to environmental variables across the gradient and is occurring despite gene flow. The pattern of divergence‐with‐gene‐flow found is similar to that described for other rainforest species across the gradient. These results suggest that neither refugia, nor isolation‐by‐distance have played a major role in divergence in the olive sunbird, although ecological differences along the forest and savanna ecotone may impose significant selection pressures on the phenotype and potentially be important in diversification. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 821–835.     

A new genus of pliosaur (Reptilia: Sauropterygia) from the Lower Jurassic of Holzmaden,Germany

Abstract: The exquisitely preserved holotype of the pliosaur ‘Rhomaleosaurus’victor (SMNS 12478) is described from the Toarcian Posidonien‐Schiefer (Upper Lias, Lower Jurassic) of Holzmaden (Baden‐Württemberg), Germany. The specimen presents a novel combination of synapomorphies and unique morphometric proportions separating it from Rhomaleosaurus sensu stricto and warranting the erection of a new genus, Meyerasaurus gen. nov. Historically, the name ‘Thaumatosaurus’ has been interchangeable with Rhomaleosaurus and is frequently associated with SMNS 12478 in the literature. However, this is an invalid taxon and cannot be reinstated. The anatomy of Meyerasaurus victor is compared in detail with other pliosaurs, and its taxonomic affinity is reviewed. M. victor belongs to the family Rhomaleosauridae and shares several anatomical characters with Rhomaleosaurus including a short and robust premaxillary rostrum (length‐to‐width ratio c. 1.0), parallel premaxilla–maxilla sutures anterior to the nares, vomers contacting the maxillae posterior to the internal nares, and c. 28 cervical vertebrae minus the atlas–axis. The known geographical distribution of Rhomaleosaurus, which previously extended across the German and English palaeobiogeographical zones, is reduced to the English zone as a consequence of the referral of SMNS 12478 to a new genus. This is significant because it contributes to an ongoing trend of increasing generic separation between the German and English zones, while increasing the generic diversity within the German zone itself.