Differential staining and microchromosomal variation in karyotypes of four Brazilian species of Tupinambinae lizards (Squamata : Teiidae)

Kayotypes of four neotropical teiid lizard species (Tupinambinae) were herein studied after conventional as well as silver staining and CBG-banding: Crocodilurus amazonicus (2n = 34), Tupinambis teguixin (2n = 36), Tupinambis merianae and Tupinambis quadrilineatus (2n = 38). The karyological data for T. quadrilineatus as well as those obtained using differential staining for all species were unknown until now. The karyotypes of all species presented 12 macrochromosomes identical in morphology, but differed in the number of microchromosomes: 22 in C. amazonicus, 24 in T. teguixin and 26 in T. quadrilineatus and T. merianae. The Ag-NOR located at the secondary constriction at the distal end of pair 2 is shared by all species, contrasting with the variability observed for this character in species of the related Teiinae. CBG-banding revealed a species-specific pattern in T. quadrilineatus with conspicuous interstitial C-blocks at the proximal region of the long arm of pair 4 and the whole heterochromatic short arm of pair 6. The karyological data reported here corroborates the relationship hypothesis obtained for Tupinambis based on molecular characters. T. teguixin presents the putative ancestral karyotype for the genus with 2n = 36 whereas T. merianae and T. quadrilineatus exhibit 2n = 38, due to an additional pair of microchromosomes.

Using ecological niche modelling to infer past, present and future environmental suitability for Leiopelma hochstetteri, an endangered New Zealand native frog

Leiopelma hochstetteri is an endangered New Zealand frog now confined to isolated populations scattered across the North Island. A better understanding of its past, current and predicted future environmental suitability will contribute to its conservation which is in jeopardy due to human activities, feral predators, disease and climate change. Here we use ecological niche modelling with all known occurrence data (N = 1708) and six determinant environmental variables to elucidate current, pre-human and future environmental suitability of this species. Comparison among independent runs, subfossil records and a clamping method allow validation of models. Many areas identified as currently suitable do not host any known populations. This apparent discrepancy could be explained by several non exclusive hypotheses: the areas have not been adequately surveyed and undiscovered populations still remain, the model is over simplistic; the species` sensitivity to fragmentation and small population size; biotic interactions; historical events. An additional outcome is that apparently suitable, but frog-less areas could be targeted for future translocations. Surprisingly, pre-human conditions do not differ markedly highlighting the possibility that the range of the species was broadly fragmented before human arrival. Nevertheless, some populations, particularly on the west of the North Island may have disappeared as a result of human mediated habitat modification. Future conditions are marked with higher temperatures, which are predicted to be favourable to the species. However, such virtual gain in suitable range will probably not benefit the species given the highly fragmented nature of existing habitat and the low dispersal ability of this species. (C) 2010 Elsevier Ltd. All rights reserved.

CONSIDERATIONS ON THE REINTRODUCTION AND RECOVERY OF THE ALAGOAS CURASSOW MITU MITU (LINNAEUS, 1766) FROM EXTINCTION USING A POTENTIALLY HYBRID CAPTIVE STOCK

The Alagoas Curassow Mitu mitu is considered extinct in the wild. Since 1979, two females and a male caught in the wild have bred successfully in captivity, and, in 1990, hybridizations between M. mitu and Razor-billed Mitu M. tuberosum were performed. By June 2008, there were around 130 living birds in two different aviaries. We sequenced two regions of the mitochondrial DNA of both captive stocks of Alagoas Curassows. We unequivocally identified hybrids that have haplotype typical of M. tuberosum. However, unless the original studbook can be recovered there is no confident way to discriminate ""pure"" M. mitu birds for breeding and reintroduction purposes. Allied with morphological data gathered in an independent study, we suggest that conservation actions need to focus on specimens with diagnostic phenotypic characters of M. mitu, and avoid birds with mitochondria, genetic contribution of M. tuberosum. Although we have detected low levels of genetic variability among captive birds, the steady increase of the captive population suggests that inbreeding depression and hybridization are not a reproductive hindrance. Reintroduction of some of these potential hybrid birds in the original area of occurrence of the Alagoas Curassow may be the only hope to fill in the ecological niche left vacant. An educational program involving local communities to conserve future reintroduction of curassows and their restored habitat is highly recommended. Accepted 12 November 2009.

Strain variation in ppGpp concentration and RpoS levels in laboratory strains of Escherichia coli K-12

Laboratory strains and natural isolates of Escherichia coli differ in their level of stress resistance due to strain variation in the level of the sigma factor sigma(S) (or RpoS), the transcriptional master controller of the general stress response. We found that the high level of RpoS in one laboratory strain (MC4100) was partially dependent on an elevated basal level of ppGpp, an alarmone responding to stress and starvation. The elevated ppGpp was caused by two mutations in spoT, a gene associated with ppGpp synthesis and degradation. The nature of the spoT allele influenced the level of ppGpp in both MC4100 and another commonly used K-12 strain, MG1655. Introduction of the spoT mutation into MG1655 also resulted in an increased level of RpoS, but the amount of RpoS was lower in MG1655 than in MC4100 with either the wild-type or mutant spoT allele. In both MC4100 and MG1655, high ppGpp concentration increased RpoS levels, which in turn reduced growth with poor carbon sources like acetate. The growth inhibition resulting from elevated ppGpp was relieved by rpoS mutations. The extent of the growth inhibition by ppGpp, as well as the magnitude of the relief by rpoS mutations, differed between MG1655 and MC4100. These results together suggest that spoT mutations represent one of several polymorphisms influencing the strain variation of RpoS levels. Stress resistance was higher in strains with the spoT mutation, which is consistent with the conclusion that microevolution affecting either or both ppGpp and RpoS can reset the balance between self-protection and nutritional capability, the SPANC balance, in individual strains of E coli.

Analysis of genotypic variation in genes associated with virulence in Aggregatibacter actinomycetemcomitans clinical isolates

Background and Objective: Although certain serotypes of Aggregatibacter actinomycetemcomitans are associated more with aggressive periodontitis than are other serotypes, the correlation between distinct lineages and virulence traits in this species is poorly understood. This study aimed to evaluate the polymorphism of genes encoding putative virulence factors of clinical isolates, and to correlate these findings with A. actinomycetemcomitans serotypes, genotypes and periodontal status of the hosts. Material and Methods: Twenty-six clinical isolates from diverse geographic populations with different periodontal conditions were evaluated. Genotyping was performed using pulse-field gel electrophoresis. Polymorphisms in the genes encoding leukotoxin, Aae, ApaH and determinants for serotype-specific O polysaccharide were investigated. Results: The isolates were classified into serotypes a-f, and exhibited three apaH genotypes, five aae alleles and 25 macrorestriction profiles. Two serotype b isolates (7.7%), obtained from Brazilian patients with aggressive periodontitis, were associated with the highly leukotoxic genotype; these isolates showed identical fingerprint patterns and aae and apaH genotypes. Serotype c, obtained from various periodontal conditions, was the most prevalent among Brazilian isolates, and isolates were distributed in two aae alleles, but formed a genetically distinct group based on apaH analysis. Cluster analysis showed a close relationship between fingerprinting genotypes and serotypes/apaH genotypes, but not with aae genotypes. Conclusion: Apart from the deletion in the ltx promoter region, no disease-associated markers were identified. Non-JP2-like strains recovered from individuals with periodontal disease exhibited considerable genetic variation regarding aae/apaH genotypes, serotypes and XhoI DNA fingerprints.

Technical variation in a sample of high level judo players

Technical actions performed by two groups of judokas who won medals at World Championships and Olympic Games during the period 1995-2001 were analyzed. In the Super Elite group (n = 17) were the best athletes in each weight category. The Elite group (n = 16) were medal winners who were not champions and did not win more than three medals. Super Elite judokas used a greater number of throwing techniques which resulted in scores, even when expressed relative to the total number of matches performed, and these techniques were applied in more directions than those of Elite judokas. Further, the number of different throwing techniques and the variability of directions in which techniques were applied were significantly correlated with number of wins and the number of points and ippon scored. Thus, a greater number of throwing techniques and use of directions for attack seem to be important in increasing unpredictability during judo matches.

Intraspecific variation in 16S rRNA gene of Mycoplasma synoviae determined by DNA sequencing

Mycoplasma synoviae (MS) is an important avian pathogen may cause both respiratory disease and joint inflammation synovitis in poultry, causing economic losses to the Brazilian poultry industry. The genotypic variation in 16S rRNA gene is unknown. Partial sequences of 16S rRNA gene of 19 strains of M. synoviae were sequenced and analyzed in order to obtain molecular characterization and evaluation of the genetic variability of strains from distinct Brazilian areas of poultry production. Different polymorphic patterns were observed. The number of polymorphic alterations in the studied strains ranged from 0 to 6. The nucleotide variations, including deletion, insertion and substitutions, ranged from 3 to 5. The genotypic diversity observed in this study may be explained by spontaneous mutations that may occur when a lineage remains in the same flock for long periods. The culling and reposition in poultry flocks may be responsible for the entry of new strains in different areas. (C) 2008 Elsevier Ltd. All rights reserved.

Intraspecific sequence variation in 16S rRNA gene of Ureaplasma diversum isolates

Ureaplasma diversum infection in bulls may result in seminal vesiculitis, balanoposthitis and alterations in spermatozoids. In cows, it can cause placentitis, fetal alveolitis, abortion and the birth of weak calves. U. diversum ATCC 49782 (serogroups A), ATCC 49783 (serogroup C) and 34 field isolates were used for this study. These microorganisms were submitted to Polymerase Chain Reaction for 16S gene sequence determination using Tact High Fidelity and the products were purified and bi-directionally sequenced. Using the sequence obtained, a fragment containing four hypervariable regions was selected and nucleotide polymorphisms were identified based on their position within the 16S rRNA gene. Forty-four single nucleotide polymorphisms (SNP) were detected. The genotypic variability of the 16S rRNA gene of U. diversum isolates shows that the taxonomy classification of these organisms is likely much more complex than previously described and that 16S rRNA gene sequencing may be used to suggest an epidemiologic pattern of different origin strains. (c) 2011 Elsevier B.V. All rights reserved.

Protein variation in blood-dwelling schistosome worms generated by differential splicing of micro-exon gene transcripts

Schistosoma mansoni is a well-adapted blood-dwelling parasitic helminth, persisting for decades in its human host despite being continually exposed to potential immune attack. Here, we describe in detail micro-exon genes (MEG) in S. mansoni, some present in multiple copies, which represent a novel molecular system for creating protein variation through the alternate splicing of short (<= 36 bp) symmetric exons organized in tandem. Analysis of three closely related copies of one MEG family allowed us to trace several evolutionary events and propose a mechanism for micro-exon generation and diversification. Microarray experiments show that the majority of MEGs are up-regulated in life cycle stages associated with establishment in the mammalian host after skin penetration. Sequencing of RT-PCR products allowed the description of several alternate splice forms of micro-exon genes, highlighting the potential use of these transcripts to generate a complex pool of protein variants. We obtained direct evidence for the existence of such pools by proteomic analysis of secretions from migrating schistosomula and mature eggs. Whole-mount in situ hybridization and immunolocalization showed that MEG transcripts and proteins were restricted to glands or epithelia exposed to the external environment. The ability of schistosomes to produce a complex pool of variant proteins aligns them with the other major groups of blood parasites, but using a completely different mechanism. We believe that our data open a new chapter in the study of immune evasion by schistosomes, and their ability to generate variant proteins could represent a significant obstacle to vaccine development.

Är variation i STFI-tjocklek ett bra mått på kartongs bulighet? : Are variation in STFI-thickness a good measure of uneven surface, bumpiness, on cardboard?

This degree project aim to evaluate if variations of the STFI thickness can be used to assess bumpiness on cardboard. During the project cardboard samples were measured using Bendtsen, PPS, a L&W formation tester, OptiTopo, Ambertec formation, the STFI thickness tester and a visual comparison. The different methods were then compared to see if there is any correlations between them. The results showed that the visual comparison and OptiTopo correlates. The STFI thickness tester shows however no correlation with the OptiTopo and visual comparison, thus aren't suitable measuring bumpiness.

Variation of System Performance with Design and Climate for Combisystems in Sweden

In Sweden, 90% of the solar heating systems are solar domestic hot water and heating systems (SDHW&H), so called combisystems. These generally supply most of the domestic hot water needs during the summer and have enough capacity to supply some energy to the heating system during spring and autumn. This paper describes a standard Swedish combisystem and how the output from it varies with heating load, climate within Sweden, and how it can be increased with improved system design. A base case is defined using the standard combi- system, a modern Swedish single family house and the climate of Stockholm. Using the simulation program Trnsys, parametric studies have been performed on the base case and improved system designs. The solar fraction could be increased from 17.1% for the base case to 22.6% for the best system design, given the same system size, collector type and load. A short analysis of the costs of changed system design is given, showing that payback times for additional investment are from 5-8 years. Measurements on system components in the laboratory have been used to verify the simulation models used. More work is being carried out in order to find even better system designs, and further improvements in system performance are expected.

Färg och missfärgning hos sågad björk : - Variation samt effekter av avverkningstidpunkt, lagring av timmer och torkning av sågad vara

Variation i björkvirkets färg beror på art, läge i träd, ursprung och lagringstid. Vårtbjörk har en mörkare färg än glasbjörk, men livligare struktur och glans. Timmer hugget under tillväxtsäsongen bör sågas färskt eller lagras högst en månad. Vid brädgårdstorkning är god luftcirkulation och skydd för väta och direkt solljus väsentligt. Strövirkets färskhet är av stor betydelse för att undvika fuktfärgning av virket.Variation in birch colours depend on species, position in tree, origin and the storage period. White birch is darker than hairy birch but with a lively structure and shine. During vegetation period timber storage exceeding one month should be avoided. Air circulation, protection from rain and direct sunlight are essential for yard drying. Freshness of stickers used for stacking is important to avoid water marks on wood surface.

A Linguistic Analysis of the Written Production of Second Language Learners : The Variation of Article Usage by Adult Chinese Learners of English

This study aims to test Robertson’s lexical transfer principle, which posits that Chinese learners use demonstratives (particularly this) and the numeral one as markers of definiteness and indefiniteness. This is tested by analysing Chinese learners’ written production collected from the Spoken and Written English Corpus of Chinese Learners 2.0 (SWECCL 2.0). The purpose is to understand the variation of article usage by adult Chinese learners of English. More specifically, the study examines to what extent articles, possessive and demonstrative pronouns are used in Chinese learners’ English and how definite and indefinite articles are used by the Chinese learners. Findings suggest that Robertson’s lexical transfer principle was corroborated by the present study. In addition, Chinese learners prefer to use demonstrative determiners, the possessive determiner our, and the numeral one to perform the function of marking definiteness and indefiniteness. In particular, the learners try to use the demonstrative determiners that and this in the anaphoric function instead of the definite article, and the demonstrative determiner those is frequently used in the cataphoric function. What is more, the learners use the numeral one as a marker of indefiniteness, and it is also used as a marker of definiteness in the anaphoric function. Further, the possessive determiner our is used as a marker of definiteness in larger situation uses referring to something unique. To this end, the study is able to show that the definite article is used to perform the function of marking indefiniteness, and in some particular contexts the definite article functions as a Chinese specifier in Chinese learners’ English. Also, the indefinite article is frequently used in quantifier phrases but is rarely used in other functions. There are three main reasons that may explain why Chinese learners use determiners variously. Firstly, the choice of determiners by Chinese learners is influenced by linguistic contexts. Secondly, because of learning strategies, Chinese learners try to ignore the anaphoric function and cataphoric function that they are not yet ready to process in article usage. Thirdly, interlanguage grammar influences the optionality in the use of articles. 

Defining the role of common variation in the genomic and biological architecture of adult human height

Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated ∼2,000, ∼3,700 and ∼9,500 SNPs explained ∼21%, ∼24% and ∼29% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/β-catenin and chondroitin sulfate-related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.2014