Differentiation of chloroplast lamellae: Light harvesting efficiency and grana development

Incomplete development of chloroplast lamellae occurred when etiolated pea plants were greened under cycles of 2 min light, 118 min dark. Although the plastids had full photochemical activities, they were nearly agranal. They were also characterized by a high quantum requirement for whole chain electron transport in low light; this is thought to be the result of unequal light absorption by incompletely developed light-harvesting assemblies of photosystem I and II and a lack of regulation of excitation energy distribution between the two photosystems. Continuous illumination induced the final stages of membrane differentiation. These stages were primarily characterized by the appearance of grana stacking and an increase in photosynthetic unit size. A biphasic decrease in quantum requirement for whole chain electron transport correlated directly with the appearance of grana during the final steps of membrane assembly. Structural organization of the membrane may be related to the light-harvesting efficiency of the membrane.     

Conservation Genetic Resources for Effective Species Survival (ConGRESS): Bridging the divide between conservation research and practice

Policy makers and managers are increasingly called upon to assess the state of biodiversity, and make decisions regarding potential interventions. Genetic tools are well-recognised in the research community as a powerful approach to evaluate species and population status, reveal ecological and demographic processes, and inform nature conservation decisions. The wealth of genetic data and power of genetic methods are rapidly growing, but the consideration of genetic information and concerns in policy and management is limited by the currently low capacity of decision-makers to access and apply genetic resources. Here we describe a freely available, user-friendly online resource for decision-makers at local and national levels (http://congressgenetics.eu), which increases access to current knowledge, facilitates implementation of studies and interpretation of available data, and fosters collaboration between researchers and practitioners. This resource was created in partnership with conservation practitioners across the European Union, and includes a spectrum of taxa, ecosystems and conservation issues. Our goals here are to (1) introduce the rationale and context, (2) describe the specific tools (knowledge summaries, publications database, decision making tool, project planning tool, forum, community directory), and the challenges they help solve, and (3) summarise lessons learned. This article provides an outlook and model for similar efforts to build policy and management capacity.     

Histopathological and parasitological study of the gastrointestinal tract of dogs naturally infected with Leishmania infantum

Background

A nationwide survey on the microbial etiology of cases of subclinical mastitis in dairy cows was carried out on dairy farms in Sweden. The aim was to investigate the microbial panorama and the occurrence of antimicrobial resistance. Moreover, differences between newly infected cows and chronically infected cows were investigated.

Methods

In total, 583 quarter milk samples were collected from 583 dairy cows at 226 dairy farms from February 2008 to February 2009. The quarter milk samples were bacteriological investigated and scored using the California Mastitis Test. Staphylococci were tested for betalactamase production and presence of resistance was evaluated in all specific udder pathogens. Differences between newly infected cows and chronically infected cows were statistically investigated using logistic regression analysis.

Results

The most common isolates of 590 bacteriological diagnoses were Staphylococcus (S) aureus (19%) and coagulase-negative staphylococci (CNS; 16%) followed by Streptococcus (Str) dysgalactiae (9%), Str. uberis (8%), Escherichia (E.) coli (2.9%), and Streptococcus spp. (1.9%). Samples with no growth or contamination constituted 22% and 18% of the diagnoses, respectively. The distribution of the most commonly isolated bacteria considering only bacteriological positive samples were: S. aureus - 31%, CNS - 27%, Str. dysgalactiae - 15%, Str. uberis - 14%, E. coli - 4.8%, and Streptococcus spp. - 3.1%. There was an increased risk of finding S. aureus, Str. uberis or Str. dysgalactiae in milk samples from chronically infected cows compared to findings in milk samples from newly infected cows. Four percent of the S. aureus isolates and 35% of the CNS isolates were resistant to penicillin G. Overall, resistance to other antimicrobials than penicillin G was uncommon.

Conclusions

Staphylococcus aureus and CNS were the most frequently isolated pathogens and resistance to antimicrobials was rare.     

Morphological integration and serial homology: A case study of the cranium and anterior vertebrae in salamanders

Serial homology or the repetition of equivalent developmental units and their derivatives is a phenomenon encountered in a variety of organisms, with the vertebrate axial skeleton as one of the most notable examples. Serially homologous structures can be viewed as an appropriate model system for studying morphological integration and modularity, due to the strong impact of development on their covariation. Here, we explored the pattern of morphological integration of the cranium and the first three serially homologous structures (atlas, first, and second trunk vertebrae) in salamandrid salamanders, using micro-CT scanning and three-dimensional geometric morphometrics. We explored the integration between structures at static and evolutionary levels. Effects of allometry on patterns of modularity were also taken into account. At the static level (within species), we analyzed inter-individual variation in shape to detect functional modules and intra-individual variation to detect developmental modules. Significant integration (based on inter-individual variation) among all structures was detected and allometry is shown to be an important integrating factor. The pattern of intra-individual, asymmetric variation indicates statistically significant developmental integration between the cranium and the atlas and between the first two trunk vertebrae. At the evolutionary level (among species), the cranium, atlas, and trunk vertebrae separate as different modules. Our results show that morphological integration at the evolutionary level coincides with morphological and functional differentiation of the axial skeleton, allowing the more or less independent evolutionary changes of the cranial skeleton and the vertebral column, regardless of the relatively strong integration at the static level. The observed patterns of morphological integration differ across levels, indicating different impacts of developmental and phylogenetic constraints and functional demands.     

Phylogenetic relationships and biogeography of midwife toads (Discoglossidae: Alytes)

Aim To devise a robust phylogenetic hypothesis for midwife toads (Alytes: Anura: Discoglossidae) and to discuss its implications for the reconstruction of the biogeographical history of the group. Location Western Palearctic. Methods Analysis of sequences of mitochondrial DNA (cytochrome b and 16S RNA, 861 bp) and 29 characters of cranial osteology of all species and subspecies within Alytes. Results Phylogenetic analyses support a sister group relationship between Alytes dickhilleni and A. muletensis, and of this clade with A. maurus. The monophyly of A. obstetricans is controversial; in particular, the phylogenetic position of A. obstetricans almogavarii is uncertain. The estimated dates for the cladogenetic events within Alytes are congruent with those derived from independent analyses (allozymes), except for the differentiation of A. o. almogavarii and the split between A. dickhilleni and A. muletensis. Main conclusions The phylogeny based on the analysis of morphological and mtDNA data differs from previous hypotheses in the positions of A. o. almogavarii and A. maurus. Events associated with the radiation of Alytes are the formation of large inland saline lakes in Iberia c. 16 Ma and the 11 ° C dramatic decrease in average annual temperature during the Middle–Late Badenian transition c. 14–13.5 Ma (A.cisternasii vs. the ancestor of the remaining clades), the structuring of the Neo‐Pyrenees and the reopening of the Betic Strait c. 10–8 Ma(A. o. almogavarii vs. A. obstetricans and vs. the subgenus Baleaphryne), the opening of the Gibraltar Strait at the end of the Messinian Salinity Crisis at c. 5.3 Ma (A. maurus vs. the ancestor of the A. dickhilleni A. muletensis clade) and a transmarine colonization event at c. 3 Ma (the ancestor of A. muletensis vs. A. dickhilleni). Following the new hypothesis, A. maurus, previously considered a subspecies of A. obstetricans, deserves species status. Second, A. o. almogavarii is a well‐differentiated lineage that was isolated from other A. obstetricans more than c. 5 Ma, but later lost its genetic and specific identity following secondary contact, hybridization and introgression with the main stock. The presence of a marked morphological and genetic diversity within A. obstetricans renders reconstruction of the evolutionary history of the genus more complicated than previously appreciated.     

The crested newt Triturus cristatus recolonized temperate Eurasia from an extra‐Mediterranean glacial refugium

We assess the role of the Carpathians as an extra‐Mediterranean glacial refugium for the crested newt Triturus cristatus. We combine a multilocus phylogeography (one mitochondrial protein‐coding gene, three nuclear introns, and one major histocompatibility complex gene) with species distribution modelling (projected on current and Last Glacial Maximum climate layers). All genetic markers consistently show extensive genetic variation within and genetic depletion outside the Carpathians. The species distribution model suggests that most of the current range was unsuitable at the Last Glacial Maximum, but a small suitable area remained in the Carpathians. Triturus cristatus dramatically expanded its postglacial range, colonizing much of temperate Eurasia from a glacial refugium in the Carpathians. Within the Carpathians, T. cristatus persisted in multiple geographically discrete regions, providing further support for a Carpathian ‘refugia within refugia’ scenario. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 574–587.     

Multilocus species tree analyses resolve the radiation of the widespread Bufo bufo species group (Anura, Bufonidae)

New analytical methods are improving our ability to reconstruct robust species trees from multilocus datasets, despite difficulties in phylogenetic reconstruction associated with recent, rapid divergence, incomplete lineage sorting and/or introgression. In this study, we applied these methods to resolve the radiation of toads in the Bufo bufo (Anura, Bufonidae) species group, ranging from the Iberian Peninsula and North Africa to Siberia, based on sequences from two mitochondrial and four nuclear DNA regions (3490 base pairs). We obtained a fully-resolved topology, with the recently described Bufo eichwaldi from the Talysh Mountains in south Azerbaijan and Iran as the sister taxon to a clade including: (1) north African, Iberian, and most French populations, referred herein to Bufo spinosus based on the implied inclusion of populations from its type locality and (2) a second clade, sister to B. spinosus, including two sister subclades: one with all samples of Bufo verrucosissimus from the Caucasus and another one with samples of B. bufo from northern France to Russia, including the Apennine and Balkan peninsulas and most of Anatolia. Coalescent-based estimations of time to most recent common ancestors for each species and selected subclades allowed historical reconstruction of the diversification of the species group in the context of Mediterranean paleogeography and indicated a long evolutionary history in this region. Finally, we used our data to delimit the ranges of the four species, particularly the more widespread and historically confused B. spinosus and B. bufo, and identify potential contact zones, some of which show striking parallels with other co-distributed species.     

Hybrid zone formation and contrasting outcomes of secondary contact over transects in common toads

Much progress in speciation research stems from documenting patterns of morphological and genetic variation in hybrid zones. Contrasting patterns of marker introgression in different sections of the contact can provide valuable insights on the relative importance of various evolutionary mechanisms maintaining species differences in the face of hybridization and gene flow and on hybrid zone temporal and spatial dynamics. We studied species interactions in the common toads Bufo bufo and B. spinosus in France and northwestern Italy using morphological and molecular data from the mitochondrial and nuclear genomes in an extensive survey, including two independent transects west and east of the Alps. At both, we found sharp, coincident and concordant nuclear genetic transitions. However, morphological clines were wider or absent and mtDNA introgression was asymmetric. We discuss alternative, nonexclusive hypotheses about evolutionary processes generating these patterns, including drift, selection, long‐distance dispersal and spatial shifts in hybrid zone location and structure. The distribution of intraspecific mtDNA lineages supports a scenario in which B. bufo held a local refugium during the last glacial maximum. Present‐day genetic profiles are best explained by an advance of B. spinosus from a nearby Iberian refugium, largely superseding the local B. bufo population, followed by an advance of B. bufo from the Balkans, with prongs north and south of the Alps, driving B. spinosus southwards. A pendulum moving hybrid zone, first northwards and then southwards, explains the wide areas of introgression at either side of the current position of the contact zones.     

Ice premelting during differential scanning calorimetry

Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important.