Geographical gradients in seed mass in relation to climate

Aim To determine whether latitudinal and longitudinal gradients in seed mass are related to variation in climatic features including temperature, solar radiation and rainfall. Location Australia. Methods Seed mass was estimated from over 1600 provenances covering the latitudinal and longitudinal extents of 34 perennial Glycine taxa in Australia. Climatic data were obtained from ANUCLIM 5.1 for collection locations based on long‐term meteorological records across Australia. These climatic data were subject to principal components analysis to extract three components as climatic indices. Generalized linear models were used in three separate sets of analyses to evaluate whether seed mass–latitude and seed mass–longitude relationships persisted after taking climatic variation into account. First, relationships were examined across species in analyses that did not explicitly consider phylogenetic relationships. Secondly, phylogenetic regressions were performed to examine patterns of correlated evolutionary change throughout the Glycine phylogeny. Within‐species analysis was also performed to examine consistency across different taxonomic levels. Results Geographical variation in seed mass among species was related primarily to temperature and solar radiation, while rainfall was much less influential upon seed mass. Partialing out the influence of temperature and solar radiation in models resulted in the disappearance of significant seed mass–latitude and seed mass–longitude relationships. Patterns within species were generally consistent with patterns among species. However, in several species, factors additional to these climatic variables may contribute to the origin and maintenance of geographical gradients in seed mass, as significant seed mass–latitude and seed mass–longitude relationships remained after controlling for the influence of climatic variables. Main conclusions Our empirical results support the hypotheses that (1) seed mass is larger at low latitudes and in the interior of the Australian continent due to increased metabolic costs at high temperatures, and that (2) higher levels of solar radiation result in an increase in the availability of photosynthate, which in turn leads to an increase in biomass for the production of large seeds. In effect, our findings show that greater energy is available precisely where needed, that is, where high temperatures require large seed mass on the basis of metabolic requirements.     

Enols as potent antibacterial agents.

This paper describes the discovery of alpha-trifluoroketoacetamides as potent antibacterial agents against Gram-positive organisms. The initial SAR indicates that the aryl ethyl side chain is essential in maintaining antibacterial activity. The SAR observations have been utilized to design a bioisostere for the alpha-trifluoroketoacetamide with good activity against Gram-positive organisms.     

Dual Y-chromosome painting and immunofluorescence staining of archival human liver transplant biopsies.

Combining fluorescence in situ hybridization (FISH) and indirect immunofluorescence staining of protein markers provides a highly specific method for identifying chromosomes in phenotypically defined cells and tissues. We developed a technique enabling dual chromosome painting and immunofluorescence staining of archival formalin-fixed, paraffin-embedded material, and used this to phenotype chimeric cells in female-to-male human liver transplants.     

Extrapair paternity and egg hatchability in tree swallows: evidence for the genetic compatibility hypothesis?

Tree swallows (Tachycineta bicolor) show one of the highestlevels of extrapair paternity in birds, and there is evidencethat females have control over who fathers their offspring.However, it is unclear which benefits female tree swallows obtainfrom mating with multiple males. Using microsatellite DNA fingerprinting,we studied extrapair paternity in relation to nesting successand male, female, and offspring characteristics. More than 70%of all nests contained extrapair young, and more than half ofall offspring were extrapair. Within broods, the extrapair youngwere often fathered by several males. Despite screening allresident and some floater males, we could identify the biologicalfather of only 21% of all extrapair offspring. All identifiedextrapair males were close neighbors. Extrapair males did notdiffer from within-pair males in any of the measured characteristics,except that the former had larger cloacal protuberances than thelatter. Extrapair males were equally successful in gaining paternityin their own broods as males that did not father extra young.In nests with mixed paternity, extrapair young did not differfrom within-pair young in body size or mass. However, nestswith extrapair young had higher hatching success than nestswithout extrapair young. All examined unhatched eggs were fertilizedand thus hatch failure resulted from embryo mortality. The availabledata are in accordance with the genetic diversity and the geneticcompatibility hypothesis, but not with the good genes hypothesis.     

Prevalence and phenotype consequence of FRAXA and FRAXE alleles in a large,ethnically diverse,special education-needs population.

We conducted a large population-based survey of fragile X (FRAXA) syndrome in ethnically diverse metropolitan Atlanta. The eligible study population consisted of public school children, aged 7-10 years, in special education-needs (SEN) classes. The purpose of the study was to estimate the prevalence among whites and, for the first time, African Americans, among a non-clinically referred population. At present, 5 males with FRAXA syndrome (4 whites and 1 African American), among 1,979 tested males, and no females, among 872 tested females, were identified. All males with FRAXA syndrome were mentally retarded and had been diagnosed previously. The prevalence for FRAXA syndrome was estimated to be 1/3,460 (confidence interval [CI] 1/7,143-1/1,742) for the general white male population and 1/4, 048 (CI 1/16,260-1/1,244) for the general African American male population. We also compared the frequency of intermediate and premutation FRAXA alleles (41-199 repeats) and fragile XE syndrome alleles (31-199 repeats) in the SEN population with that in a control population, to determine if there was a possible phenotype consequence of such high-repeat alleles, as has been reported previously. No difference was observed between our case and control populations, and no difference was observed between populations when the probands were grouped by a rough estimate of IQ based on class placement. These results suggest that there is no phenotype consequence of larger alleles that would cause carriers to be placed in an SEN class.     

The population genetics of the causative agent of snake fungal disease indicate recent introductions to the USA

Snake fungal disease (SFD; ophidiomycosis), caused by the pathogen Ophidiomyces ophiodiicola (Oo), has been documented in wild snakes in North America and Eurasia, and is considered an emerging disease in the eastern United States of America. However, a lack of historical disease data has made it challenging to determine whether Oo is a recent arrival to the USA or whether SFD emergence is due to other factors. Here, we examined the genomes of 82 Oo strains to determine the pathogen’s history in the eastern USA. Oo strains from the USA formed a clade (Clade II) distinct from European strains (Clade I), and molecular dating indicated that these clades diverged too recently (approximately 2,000 years ago) for transcontinental dispersal of Oo to have occurred via natural snake movements across Beringia. A lack of nonrecombinant intermediates between clonal lineages in Clade II indicates that Oo has actually been introduced multiple times to North America from an unsampled source population, and molecular dating indicates that several of these introductions occurred within the last few hundred years. Molecular dating also indicated that the most common Clade II clonal lineages have expanded recently in the USA, with time of most recent common ancestor mean estimates ranging from 1985 to 2007 CE. The presence of Clade II in captive snakes worldwide demonstrates a potential mechanism of introduction and highlights that additional incursions are likely unless action is taken to reduce the risk of pathogen translocation and spillover into wild snake populations.

Snake fungal disease is an emerging disease in eastern North America, but the origins of the disease have been unclear. This study uses population genetic data to show that the fungus that causes the disease was introduced multiple times to North America over the last few hundred years.     

A versatile computational pipeline for bacterial genome annotation improvement and comparative analysis, with Brucella as a use case

We present a bacterial genome computational analysis pipeline, called GenVar. The pipeline, based on the program GeneWise, is designed to analyze an annotated genome and automatically identify missed gene calls and sequence variants such as genes with disrupted reading frames (split genes) and those with insertions and deletions (indels). For a given genome to be analyzed, GenVar relies on a database containing closely related genomes (such as other species or strains) as well as a few additional reference genomes. GenVar also helps identify gene disruptions probably caused by sequencing errors. We exemplify GenVar's capabilities by presenting results from the analysis of four Brucella genomes. Brucella is an important human pathogen and zoonotic agent. The analysis revealed hundreds of missed gene calls, new split genes and indels, several of which are species specific and hence provide valuable clues to the understanding of the genome basis of Brucella pathogenicity and host specificity.     

Isolation, Identification, and Metabolic Role of the Sudanophilic Granules of Zoogloea ramigera

Organisms isolated from activated sludge and identified as Zoogloea ramigera accumulated large amounts of sudanophilic granules as the cultures flocculated. The granules were extracted by chloroform and precipitated with ether from acid-hydrolyzed cells. Identification of the sudanophilic granules as poly-β-hydroxybutyric acid (PHB) was confirmed by physical, chemical, and infrared spectral analyses. The isolated polymer accounted for 12.0 to 50.5% of the dry weight of the cells. The polymer was not synthesized when the culture was grown in a growth-limiting concentration of organic substrate; it did accumulate when the culture was grown in medium enriched with carbon and energy sources. An increase in concentration of intracellular PHB was directly proportional to optical density and uptake of glucose. Aside from intracellular storage of PHB as endogenous metabolite, the accumulation of PHB is noted as a possible mechanism of flocculation.     

Fur seals at Macquarie Island: post-sealing colonisation,trends in abundance and hybridisation of three species

Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The first breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954–2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is significant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been affected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.