Space use and genetic structure do not maintain color polymorphism in a species with alternative behavioral strategies

Space use including territoriality and spatial arrangement within a population can reveal important information on the nature, dynamics, and evolutionary maintenance of alternative strategies in color polymorphic species. Despite the prevalence of color polymorphic species as model systems in evolutionary biology, the interaction between space use and genetic structuring of morphs within populations has rarely been examined. Here, we assess the spatial and genetic structure of male throat color morphs within a population of the tawny dragon lizard, Ctenophorus decresii. Male color morphs do not differ in morphology but differ in aggressive and antipredator behaviors as well as androgen levels. Despite these behavioral and endocrine differences, we find that color morphs do not differ in territory size, with their spatial arrangement being essentially random with respect to each other. There were no differences in genetic diversity or relatedness between morphs; however, there was significant, albeit weak, genetic differentiation between morphs, which was unrelated to geographic distance between individuals. Our results indicate potential weak barriers to gene flow between some morphs, potentially due to nonrandom pre‐ or postcopulatory mate choice or postzygotic genetic incompatibilities. However, space use, spatial structure, and nonrandom mating do not appear to be primary mechanisms maintaining color polymorphism in this system, highlighting the complexity and variation in alternative strategies associated with color polymorphism.     

CORRESPONDENCE BETWEEN PHYLOGENY AND MORPHOLOGY OF SNOWELLA SPP. AND WORONICHINIA NAEGELIANA,CYANOBACTERIA COMMONLY OCCURRING IN LAKES1

In this study, the first reported isolates of the genera Snowella and Woronichinia were characterized by 16S rRNA gene sequencing and morphological analysis. Phylogenetic studies and sequences for these genera were not available previously. By botanical criteria, the five isolated strains were identified as Snowella litoralis (Häyrén) Komárek et Hindák Snowella rosea (Snow) Elenkin and Woronichinia naegeliana (Unger) Elenkin. This study underlines the identification of freshly isolated cultures, since the Snowella strains lost the colony structure and were not identifiable after extended laboratory cultivation. In the 16S rRNA gene analysis, the Snowella strains formed a monophyletic cluster, which was most closely related to the Woronichinia strain. Thus, our results show that the morphology of the genera Snowella and Woronichinia was in congruence with their phylogeny, and their phylogeny seems to support the traditional botanical classification of these genera. Furthermore, the genera Snowella and Woronichinia occurred commonly and might occasionally be the most abundant cyanobacterial taxa in mainly oligotrophic and mesotrophic Finnish lakes. Woronichinia occurred frequently and also formed blooms in eutrophic Czech reservoirs.     

Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Deactivation ofCandida rugosa lipase

Summary Deactivation ofCandida rugosa lipase was found to be complex. Hydrophobic interaction induced by iso-octane influenced the initial phase of deactivation, and increased the turn-over rate of the intermediate in the transition phase. After urea-treatment the structure of the last phase was not further influenced by thermal treatment, whereas that of initial phase was more sensitive to temperature change. Charge interaction was important in maintaining the structure during the deactivation, and especially anion charge might be a major factor.     

Genetic and physical analyses of a cluster of genes essential for xanthan gum biosynthesis in Xanthomonas campestris.

Xanthomonas campestris produces copious amounts of a complex exopolysaccharide, xanthan gum. Nonmucoid mutants, defective in synthesis of xanthan polysaccharide, were isolated after nitrosoguanidine mutagenesis. To isolate genes essential for xanthan polysaccharide synthesis (xps), a genomic library of X. campestris DNA, partially digested with SalI and ligated into the broad-host-range cloning vector pRK293, was constructed in Escherichia coli. The pooled clone bank was conjugated en masse from E. coli into three nonmucoid mutants by using pRK2013, which provides plasmid transfer functions. Kanamycin-resistant exconjugants were then screened for the ability to form mucoid colonies. Analysis of plasmids from several mucoid exconjugants indicated that overlapping segments of DNA had been cloned. These plasmids were tested for complementation of eight additional nonmucoid mutants. A 22-kilobase (kb) region of DNA was defined physically by restriction enzyme analysis and genetically by ability to restore mucoid phenotype to 10 of the 11 nonmucoid mutants tested. This region was further defined by subcloning and by transposon mutagenesis with mini-Mu(Tetr), with subsequent analysis of genetic complementation of nonmucoid mutants. A region of 13.5 kb of DNA was determined to contain at least five complementation groups. The effect of plasmids containing cloned xps genes on xanthan gum synthesis was evaluated. One plasmid, pCHC3, containing a 12.4-kb insert and at least four linked xanthan biosynthetic genes, increased the production of xanthan gum by 10% and increased the extent of pyruvylation of the xanthan side chains by about 45%. This indicates that a gene affecting pyruvylation of xanthan gum is linked to this cluster of xps genes.