Investigation into the Paleobiology of Dasypus bellus Using Geometric Morphometrics and Variation of the Calcaneus

The extinct taxon Dasypus bellus has long been considered identical to the extant Dasypus novemcinctus osteologically when disregarding allometric differences. In this study, we undertake a preliminary investigation into this extinct taxon and an extant relative D. novemcinctus, by comparing the calcanea of these two dasypodids. Clear osteological differences are observed including a mediolaterally-reduced facet region, an anteriorly-shortened calcaneal head, a reduced peroneal process, and a curved and dorsoventrally-shortened calcaneal foot in D. bellus. Such characters are not allometric and likely correlate to distinct behavioral differences. Specifically, we suggest that D. novemcinctus maintains a more fossorial lifestyle, while the larger D. bellus was likely more terrestrial, with potentially little digging behavior. Such lifestyle differences could not only explain the osteological differences present, but also why fossils of D. bellus have been recovered farther north than the present range of D. novemcinctus. Fossils of Dasypus may need to be re-evaluated to determine how these two taxa relate temporally and geographically, which may have further implications regarding some past interpretations and provide new details on the behavior and potential relationships between these (and other) xenarthrans.     

The gum exudates from some acacia subspecies of the series botryocephalae

Gum specimens from A. deanei subsp. paucijuga (two samples), A. irrorata subsp. irrorata, and A. dealbata subsp. subalpina have been analysed. There are minor differences between the two specimens from A. deanei subsp. paucijuga, but they, and the gum from A. irrorata subsp. irrorata, have analytical parameters that correspond well with those for species in the proposed Group A within the Botryocephalae. In contrast, the gum from A. dealbata subsp. subalpina conforms well with the analytical parameters established for A. dealbata gum, and the slight analytical differences lead to it being assigned with greater confidence to the proposed Group B. Now that the gum exudates from approximately 40% of the species within the Botryocephalae have been studied and shown to fall into two different types, it is hoped that the chemical data may be meaningful taxonomically.     

Shape Ontogeny of the Distal Femur in the Hominidae with Implications for the Evolution of Bipedality

Heterochrony has been invoked to explain differences in the morphology of modern humans as compared to other great apes. The distal femur is one area where heterochrony has been hypothesized to explain morphological differentiation among Plio-Pleistocene hominins. This hypothesis is evaluated here using geometric morphometric data to describe the ontogenetic shape trajectories of extant hominine distal femora and place Plio-Pleistocene hominins within that context. Results of multivariate statistical analyses showed that in both Homo and Gorilla, the shape of the distal femur changes significantly over the course of development, whereas that of Pan changes very little. Development of the distal femur of Homo is characterized by an elongation of the condyles, and a greater degree of enlargement of the medial condyle relative to the lateral condyle, whereas Gorilla are characterized by a greater degree of enlargement of the lateral condyle, relative to the medial. Early Homo and Australopithecus africanus fossils fell on the modern human ontogenetic shape trajectory and were most similar to either adult or adolescent modern humans while specimens of Australopithecus afarensis were more similar to Gorilla/Pan. These results indicate that shape differences among the distal femora of Plio-Pleistocene hominins and humans cannot be accounted for by heterochrony alone; heterochrony could explain a transition from the distal femoral shape of early Homo/A. africanus to modern Homo, but not a transition from A. afarensis to Homo. That change could be the result of genetic or epigenetic factors.     

Characterization of extracellular proteins in members of the Paracoccidioides complex

Paracoccidioides is a thermodimorphic fungus that causes Paracoccidioidomycosis (PCM) – an endemic systemic mycosis in Latin America. The genus comprises several phylogenetic species which present some genetic and serological differences. The diversity presented among isolates of the same genus has been explored in several microorganisms. There have also been attempts to clarify differences that might be related to virulence existing in isolates that cause the same disease. In this work, we analyzed the secretome of two isolates in the Paracoccidioides genus, isolates Pb01 and PbEpm83, and performed infection assays in macrophages to evaluate the influence of the secretomes of those isolates upon an in vitro model of infection. The use of a label-free proteomics approach (LC-MS^E) allowed us to identify 92 proteins that are secreted by those strains. Of those proteins, 35 were differentially secreted in Pb01, and 36 in PbEpm83. According to the functional annotation, most of the identified proteins are related to adhesion and virulence processes. These results provide evidence that different members of the Paracoccidioides complex can quantitatively secrete different proteins, which may influence the characteristics of virulence, as well as host-related processes.     

Computational modeling of differences in the quorum sensing induced luminescence phenotypes of Vibrio harveyi and Vibrio cholerae

Vibrio harveyi and Vibrio cholerae have quorum sensing pathways with similar design and highly homologous components including multiple small RNAs (sRNAs). However, the associated luminescence phenotypes of strains with sRNA deletions differ dramatically: in V. harveyi, the sRNAs act additively; however, in V. cholerae, the sRNAs act redundantly. Furthermore, there are striking differences in the luminescence phenotypes for different pathway mutants in V. harveyi and V. cholerae. However, these differences have not been connected with the observed differences for the sRNA deletion strains in these bacteria. In this work, we present a model for quorum sensing induced luminescence phenotypes focusing on the interactions of multiple sRNAs with target mRNA. Within our model, we find that one key parameter - the fold-change in protein concentration necessary for luminescence activation - can control whether the sRNAs appear to act additively or redundantly. For specific parameter choices, we find that differences in this key parameter can also explain hitherto unconnected luminescence phenotypes differences for various pathway mutants in V. harveyi and V. cholerae. The model can thus provide a unifying explanation for observed differences in luminescence phenotypes and can also be used to make testable predictions for future experiments.     

A developmental analysis of the histone patterns of two species of Xenopus and their hybrids

The histone patterns in Xenopus laevis and X. borealis have been examined at various developmental stages using acid-urea polyacrylamide electrophoresis. Qualitative differences between the two species have been demonstrated in the H1 fraction. These differences are not affected by alkaline phosphatase digestion. Quantitative changes during development in both H1 and H4 fractions have also been observed. In addition, histones from hybrids of the two species have been examined. H1 histones characteristic of both species are present by the neurula stage in laevis ♀ × borealis ♂ hybrids. Quantitative changes observed in borealis development are mimicked in laevis ♀ × borealis ♂ hybrid development.     

Palaeobiogeographic and metric analysis of the Mesozoic fern Weichselia

Eighty-three publications have been examined to recover information on the palaeogeography, the chronostratigraphy and the presence of the fossil fern genus Weichselia Stiehler in different depositional environments. This fossil fern foliage was reported in 72 localities worldwide. Its fossil record ranges from the Bathonian to the Cenomanian, predominating from the Berriasian to the Barremian, but still common during the Aptian to Cenomanian. Weichselia mostly occurred in continental depositional environments in Europe, whereas it has been mostly related to marginal marine depositional environments in Africa, North America, and India. Three species have been described: W. reticulata, W. peruviana, and W. negevensis. We analyse the measurements on specimens collected from sixteen localities as well as published data from twelve others. Our results suggest that: (i) the climate changes during the Aptian might have affected the pinnule size of Weichselia, as the Aptian-Cenomanian pinnules are larger than those from the Berriasian-Barremian; (ii) some differences might be explained by the metric variation of the frond parts; (iii) there are no clear differences in size between remains collected from different depositional environments; (iv) there is no sufficient evidence to determine how many species of Weichselia have existed.     

Recognition of Superior Photosynthetic Efficiency in the Field Using the CO(2)-Depletion Technique

The relationship between CO₂ exchange rate (CER) and growth of crops in the field was investigated in Connecticut Broadleaf tobacco (Nicotiana tabacum) using the CO₂-depletion technique. A particular objective was to determine if modest (i.e. <10%) varietal differences could be distinguished in mean CER. Statistical analysis of numerous CER values obtained over a wide range of irradiances during the course of the season indicated that differences of as little as 7% in the mean CER between varieties would be significant (n ~400). The usefulness of the CO₂-depletion technique in detecting modest differences in photosynthetic efficiency has thus been demonstrated. These results are discussed in relation to the prospects for introducing and detecting genetic traits which would diminish photorespiration and increase CER and growth.     

Quantitative variations in the expression of the mouse serum antigen Ss and its sex-limited allotype Slp

A radial immunodiffusion assay for quantitation of the Ss and Slp serum antigens is described. Significant differences between the mean serum concentrations of Ss and Slp were found among various inbred strains. Some of these differences have been shown to be associated with the H-2 haplotype. The quantitative difference between Slp levels associated with the H-2 ^a and H-2 ^S haplotypes has been used as a marker for the S region in the analysis of certain H-2 recombinant strains [A.TH, B10.S(7R), B10.S(9R), and B10.BSVS]. Male mice of two strains with the H-2 ^b haplotype have been shown to have significantly lower levels of Ss compared to males of the other strains tested. Male mice of every strain examined were found to have significantly higher levels of Ss in their serum than females of the same strain. The molecular relationship and developmental patterns of the Ss and Slp antigens have also been investigated using the radial immunodiffusion assay.     

Microanatomy of the abdominal stretch receptors of the crayfish (Astacus fluviatilis L.)

Microanatomical studies on the abdominal stretch receptor organs of the crayfish Astacus fluviatilis L. have been carried out in order to establish a basis for the physiological work that has been, and is being carried out on stretch receptors of various species of crayfish. Important differences have been found between these organs and those previously described by Alexandrowicz for the lobsters Homarus vulgaris and Palinurus vulgaris. With the aid of silver-impregnated preparations the relationship of sensory endings and muscle fibers has been shown as well as the pattern of the efferent innervation. The physiological significance of the histological findings has been discussed.     

The endopeptidase of the maize-affecting Marafivirus type member maize rayado fino virus doubles as a deubiquitinase

Marafiviruses are capable of persistent infection in a range of plants that have importance to the agriculture and biofuel industries. Although the genomes of a few of these viruses have been studied in-depth, the composition and processing of the polyproteins produced from their main ORFs have not. The Marafivirus polyprotein consists of essential proteins that form the viral replicase, as well as structural proteins for virus assembly. It has been proposed that Marafiviruses code for cysteine proteases within their polyproteins, which act as endopeptidases to autocatalytically cleave the polyprotein into functional domains. Furthermore, it has also been suggested that Marafivirus endopeptidases may have deubiquitinating activity, which has been shown to enhance viral replication by downregulating viral protein degradation by the ubiquitin (Ub) proteasomal pathway as well as tampering with cell signaling associated with innate antiviral responses in other positive-sense ssRNA viruses. Here, we provide the first evidence of cysteine proteases from six different Marafiviruses that harbor deubiquitinating activity and reveal intragenus differences toward Ub linkage types. We also examine the structural basis of the endopeptidase/deubiquitinase from the Marafivirus type member, maize rayado fino virus. Structures of the enzyme alone and bound to Ub reveal marked structural rearrangements that occur upon binding of Ub and provide insights into substrate specificity and differences that set it apart from other viral cysteine proteases.     

Gradients of Intercellular CO(2) Levels Across the Leaf Mesophyll

Most current photosynthesis models, and interpretations of many wholeleaf CO₂ gas exchange measurements, are based on the often unstated assumption that the partial pressure of CO₂ is nearly uniform throughout the airspaces of the leaf mesophyll. Here we present measurements of CO₂ gradients across amphistomatous leaves allowed to assimilate CO₂ through only one surface, thus simulating hypostomatous leaves. We studied five species: Eucalyptus pauciflora Sieb. ex Spreng., Brassica chinensis L., Gossypium hirsutum L., Phaseolus vulgaris L., and Spinacia oleracea L. For Eucalyptus, maximum CO₂ pressure differences across the leaf mesophyll were 73 and 160 microbar when the pressures outside the lower leaf surface were 310 and 590 microbar, respectively. Using an approximate theoretical calculation, we infer that if the CO₂ had been supplied equally at both surfaces then the respective mean intercellular CO₂ pressures would have been roughly 12 and 27 microbar less than the pressures in the substomatal cavities in these cases. For ambient CO₂ pressures near 320 microbar, the average and minimum pressure differences across the mesophyll were 45 and 13 microbar. The corresponding mean intercellular CO₂ pressures would then be roughly 8 and 2 microbar less than those in the substomatal cavities. Pressure differences were generally smaller for the four agricultural species than for Eucalyptus, but they were nevertheless larger than previously reported values.     

Quantifying the importance of protein conformation on ligand migration in myoglobin

Myoglobin (Mb) is a model system for ligand binding and migration. The energy barriers (ΔG) for ligand migration in Mb have been studied in the past by experiment and theory and significant differences between different approaches were found. From experiment, it is known that Mb can assume a large number of conformational substates. In this work, these substates are investigated as a possible source of the differences in migration barriers. We show that the initial structure significantly affects the calculated ΔG for a particular transition and that fluctuations in barrier heights δΔG are of similar magnitude as the free energy barriers themselves. The sensitivity of ΔG to the initial structure is compared to other sources of errors. Different protein structures can affect the calculated ΔG by up to 4 kcal/mol, whereas differences between simple point charge models and more elaborate multipolar charge models for the CO-ligand are smaller by a factor of two. Analysis of the structural changes underlying the large effect of the conformational substate reveals the importance of coupling between protein and ligand motion for migration.     

The impact of cis-acting polymorphisms on the human phenotype

Cis-acting polymorphisms that affect gene expression are now known to be frequent, although the extent and mechanisms by which such variation affects the human phenotype are, as yet, only poorly understood. Key signatures of cis-acting variation are differences in gene expression that are tightly associated with regulatory SNPs or expression Quantitative Trait Loci (eQTL) and an imbalance of allelic expression (AEI) in heterozygous samples. Such cis-acting sequence differences appear often to have been under selection within and between populations and are also thought to be important in speciation. Here we describe the example of lactase persistence. In medical research, variants that affect regulation in cis have been implicated in both monogenic and polygenic disorders, and in the metabolism of drugs. In this review we suggest that by further understanding common regulatory variations and how they interact with other genetic and environmental variables it will be possible to gain insight into important mechanisms behind complex disease, with the potential to lead to new methods of diagnosis and treatments.     

Differences in the pattern visual evoked potential between pregnant and non-pregnant women

It has been proposed that latencies of some components of the pattern-reversal visual evoked potential (PRVEP) are shorter in women than in men because of differences in levels of circulating sex steroids. Pregnancy is a time when serum levels of oestrogen and progestogen are considerably greater than in the non-pregnant state. Whole and half field PRVEP latencies and amplitudes have been compared in 16 pregnant and 38 healthy non-pregnant women. The mean P100 latencies for all responses were shorter in the pregnant women, with statistically significant differences for the left eye whole field latency (P < 0.05) and the left eye right and left half field latencies (P < 0.005 and P < 0.05, respectively) and the right eye right half field latency (P < 0.05). The latencies in women in the pregnant group showed a negative correlation with gestation, which reached statistical significance for the REWF (r = −0.55, P < 0.05). These observed differences in PRVEP latencies in pregnant and non-pregnant women and the association between latency and gestation are likely to be due to differences in circulating sex steroids, and this effect may be the principal reason for latency differences between the sexes.     

Differences Found in the Macroinvertebrate Community Composition in the Presence or Absence of the Invasive Alien Crayfish,Orconectes hylas

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish (Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O. hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O. hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O. hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities.     

The first female maxilla of the hominoid Ouranopithecus macedoniensis from the late Miocene of Macedonia,Greece

A maxilla with both toothrows C-M³ of a late Miocene hominoid is described. It was found at the locality Nikiti 1 (NKT) of Chalkidiki (Macedonia, Greece). The locality has been dated to late Vallesian-earliest Turolian. The morphological characters and the comparison of the new maxilla suggest that it is a female individual of Ouranopithecus macedoniensis. It is the first known female maxilla of the species. Comparison with the other two known male maxillae of Ouranopithecus macedoniensis indicates the following differences: smaller size of maxilla and teeth, smaller mesial groove in the canine, more lingually situated mesial groove in the canine, slightly smaller mesiobuccal projection in P³ and relatively shorter P⁴. There are no significant morphological differences in the molars. Various statistical parameters for the Ouranopithecus teeth have been calculated and compared with those of the extant hominoids. This comparison suggests the presence of a single species in the sample.     

A comparison of the properties of bacteriocins formed by Lactococcus lactis subsp. lactis strains of diverse origin

Bacteriocins formed by four strains of Lactococcus lactis subsp. lactis have been studied and compared: 729 (a natural strain isolated from milk), 1605 (a mutant of strain 729), F-116 (a recombinant obtained by fusing of protoplasts of the two related strain 729 and 1605), and a nisin-forming strain obtained by adaptive selection at Moscow State University. Antimicrobial activity studies revealed differences between the strains in the effects on individual groups of microorganisms; the activities of the strains were also distinct from that of Nisaplin (a commercial preparation of the bacteriocin nisin). Methods for isolation and purification of bacteriocins have been developed, making it possible to obtain individual components of antibiotic complexes as chromatographically pure preparations. Bacteriocins formed by the strains of Lactococcus lactis subsp. lactis have been identified and differences in their biological and physicochemical properties, established. A novel potent broad-spectrum antibiotic substance distinct from nisin has been isolated from the recombinant strain F-116.     

New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus

Pterodactylus antiquus has long been thought to have been quite small (~50 cm wingspan) and to have differed from P. longicollum, Ctenochasma, Germanodactylus, and Gnathosaurus in lacking a bony cranial crest, though a soft tissue crest and occipital lappet have been described. This article describes a new specimen of P. antiquus larger than all previously known specimens, which demonstrates that the species exceeded 1 m in wingspan and had a low bony cranial crest. A smaller, incipient crest was identified on the holotype specimen. Additional specimens, including the counterpart of Wellnhofer’s original occipital lappet specimen, provide evidence of the occipital lappet and the soft tissue crest extending upward above the naso-antorbital fenestra and orbit. In order to provide a proper taxonomic context for the findings, the recent synonymization of the species Pterodactylus antiquus and P. kochi on the basis of shared correlation of tooth number and skull length despite perceived differences in dentition and skull, neck, and trunk proportions is reviewed. A measurement error that had made it appear that P. antiquus differed significantly from P. kochi in proportions is documented, and after correction of the measurement error and reevaluation of the dental evidence there are no significant differences between the two nominal species. Thus, the synonymization of P. antiquus and P. kochi was appropriate, and a revised diagnosis is presented. In addition, the species P. longicollum and P. micronyx, which for some years have been viewed as not congeneric with P. antiquus, are placed in a new genus and transferred to Aurorazhdarcho, respectively.