Population structure and genetic diversity analysis in Gynaikothrips uzeli (Zimerman, 1909) (Thysanoptera: Phlaeothripidae) by RAPD markers.

Thrips are small insects (0.5-3.0 mm) with distinct habits and life histories characterized by haplodiploid sex determination. In general, low levels of genetic diversity have been reported in haplodiploid insects, although most reports focus on the order Hymenoptera. Therefore, we used RAPD markers to evaluate the structure and both inter- and intra-population genetic variability of Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae). Six populations, three from Paraná state, southern Brazil, and three from Bahia, northeastern Brazil, were studied. Similarly to other haplodiploid insects, the genetic diversity of G. uzeli was reduced. This result is putatively related to the haplodiploid sex determination system, which yields little genetic variation, and to ecological traits of the studied species, such as the low dispersal abilities and life mode in leaf galls. All individuals were homogeneously clustered in their respective collection sites, forming two main groups in which populations from similar environments were more closely related. The analyzed populations were highly structured, and the genetic variation was higher among than within populations.

Chromosomal diversity and phylogenetic inferences concerning thrips (Insecta, Thysanoptera) in a semi-arid region of Brazil.

The order Thysanoptera is composed of cosmopolitan phytophagous and predaceous insects with diverse life histories, behaviors and habits. This order is currently thought to form a trichotomy with Hemiptera and Psocodea; Hemiptera and Thysanoptera are considered to be sister groups. The interrelationships within Thysanoptera remain unclear and cytotaxonomic studies are scarce in thrips. We report, for the first time, chromosomal data on seven species of thrips collected from a semi-arid region in the States of Bahia and Pernambuco (Northeast Brazil). A distinctive chromosomal pattern was observed in Thysanoptera when compared to other members within the infraclass Paraneoptera. Considerable karyotypic differences were also found within genera and species of Thysanoptera. Based on these data, we suggest that Paraneoptera forms a polyphyletic group and that Terebrantia and Tubulifera should be regarded as sister groups. The high chromosomal variability observed in Thysanoptera indicates that chromosomal rearrangements have played a key role in their speciation pathways.

Neat DODAB vesicles: Effect of sonication time on the phase transition thermodynamic parameters and its relation with incomplete chain freezing.

Vesicle solutions formed by the cationic lipid dioctadecyldimethylammonium bromide have been extensively used in the past 20 years as model membrane systems. Often, discrepancies are found in the literature for the thermodynamic parameters of the gel-to-liquid crystal (gel-lc) phase transition of these vesicles. In this work we present a systematic DSC investigation on the influence of the sonication method on the main temperature and enthalpy of the transition for DODAB vesicles, prepared both in normal and deuterated water. It is shown that as the sonication time increases, the T(m) and enthalpy values decrease until a plateau value is reached. This effect is associated with incomplete chain crystallization in the highly curved vesicles (produced by sonication) when they are cooled below the transition temperature. The effect of aging on the sonicated solutions has also been monitored by DSC.

Allele frequencies of three STRs of the human von Willebrand factor gene (vWF) in a Brazilian population sample.

Allele frequencies were calculated for three tetrameric short tandem repeats (STRs) located in intron 40 of the human von Willebrand factor (vWA, vWF1 and vWF2) in 352 white individuals sampled from an urban population from the northeastern region of the State of São Paulo, Brazil. The exact test did not indicate any significant deviation from HWE for any of the three investigated loci. The allele frequencies of vWA and vWF1 showed unimodal and bimodal distributions, respectively, and the frequencies of vWF2 in our sample exhibited bimodal or even trimodal patterns. These differing patterns could reflect the differential action of one selective factor or of the distribution of mutations in these STRs, although the STRs are very close to one another and belong to the same gene. The frequency of paternity exclusions observed for each of these three loci conform to the theorectical expectations. The lack of difficulties regarding the methodology of typing and the forensic value of statistical parameters confirm the usefulness of these systems to study Brazilian populations.