Meiotic Transmission of Drosophila pseudoobscura Chromosomal Arrangements

Drosophila pseudoobscura harbors a rich gene arrangement polymorphism on the third chromosome generated by a series of overlapping paracentric inversions. The arrangements suppress recombination in heterokaryotypic individuals, which allows for the selective maintenance of coadapted gene complexes. Previous mapping experiments used to determine the degree to which recombination is suppressed in gene arrangement heterozygotes produced non-recombinant progeny in non-Mendelian ratios. The deviations from Mendelian expectations could be the result of viability differences between wild and mutant chromosomes, meiotic drive because of achiasmate pairing of homologues in heterokaryotypic females during meiosis, or a combination of both mechanisms. The possibility that the frequencies of the chromosomal arrangements in natural populations are affected by mechanisms other than adaptive selection led us to consider these hypotheses. We performed reciprocal crosses involving both heterozygous males and females to determine if the frequency of the non-recombinant progeny deviates significantly from Mendelian expectations and if the frequencies deviate between reciprocal crosses. We failed to observe non-Mendelian ratios in multiple crosses, and the frequency of the non-recombinant classes differed in only one of five pairs of reciprocal crosses despite sufficient power to detect these differences in all crosses. Our results indicate that deviations from Mendelian expectations in recombination experiments involving the D. pseudoobscura inversion system are most likely due to fitness differences of gene arrangement karyotypes in different environments

On Dorsal Prothoracic Appendages in Treehoppers (Hemiptera: Membracidae) and the Nature of Morphological Evidence

A spectacular hypothesis was published recently, which suggested that the “helmet” (a dorsal thoracic sclerite that obscures most of the body) of treehoppers (Insecta: Hemiptera: Membracidae) is connected to the 1st thoracic segment (T1; prothorax) via a jointed articulation and therefore was a true appendage. Furthermore, the “helmet” was interpreted to share multiple characteristics with wings, which in extant pterygote insects are present only on the 2nd (T2) and 3rd (T3) thoracic segments. In this context, the “helmet” could be considered an evolutionary novelty. Although multiple lines of morphological evidence putatively supported the “helmet”-wing homology, the relationship of the “helmet” to other thoracic sclerites and muscles remained unclear. Our observations of exemplar thoraces of 10 hemipteran families reveal multiple misinterpretations relevant to the “helmet”-wing homology hypothesis as originally conceived: 1) the “helmet” actually represents T1 (excluding the fore legs); 2) the “T1 tergum” is actually the anterior dorsal area of T2; 3) the putative articulation between the “helmet” and T1 is actually the articulation between T1 and T2. We conclude that there is no dorsal, articulated appendage on the membracid T1. Although the posterior, flattened, cuticular evagination (PFE) of the membracid T1 does share structural and genetic attributes with wings, the PFE is actually widely distributed across Hemiptera. Hence, the presence of this structure in Membracidae is not an evolutionary novelty for this clade. We discuss this new interpretation of the membracid T1 and the challenges of interpreting and representing morphological data more broadly. We acknowledge that the lack of data standards for morphology is a contributing factor to misinterpreted results and offer an example for how one can reduce ambiguity in morphology by referencing anatomical concepts in published ontologies

Comparison of diet consumption, body composition and lipoprotein lipid values of Kuwaiti fencing players with international norms

<p>Abstract</p> <p>Background</p> <p>No published data is currently available that describes the dietary patterns or physiological profiles of athletes participating on the Kuwaiti national fencing team and its potential impact on health and physical performance. The purpose of this investigation was to: 1) collect baseline data on nutrient intake 2) collect, analyze and report baseline for body composition, plasma lipid and lipoprotein concentrations during the competitive season, 3) compare the results with the international norms, 4) and provide necessary health and nutritional information in order to enhance the athletes' performance and skills.</p> <p>Methods</p> <p>Fifteen national-class fencers 21.5 ± 2.6 years of age participated in this study. Food intake was measured using a 3-day food record. Body composition was estimated using both the BOD POD and Body Mass Index (BMI). Total blood lipid profiles and maximum oxygen consumption was measured for each of the subjects during the competitive season.</p> <p>Results</p> <p>The results of the present study showed significant differences in dietary consumption in comparison with the recommended dietary allowances (RDA). The blood lipids profile and body composition (BMI and % body fat) were in normal range in comparison with international norms However, the average VO_{2 max}value was less than the value of the other fencers.</p> <p>Conclusion</p> <p>Due to the results of the research study, a dietary regimen can be designed that would better enhance athletic performance and minimize any health risks associated with nutrition. Percent body fat and BMI will also be categorized for all players. In addition, the plasma blood tests will help to determine if any of the players have an excessive level of lipids or any blood abnormalities. The outcomes of present study will have a direct impact on the players health and therefore their skills and athletic performance.</p

Bradykinin type 2 receptor -9/-9 genotype is associated with triceps brachii muscle hypertrophy following strength training in young healthy men

<p>Abstract</p> <p>Background</p> <p>Bradykinin type 2 receptor (<it>B2BRK)</it> genotype was reported to be associated with changes in the left-ventricular mass as a response to aerobic training, as well as in the regulation of the skeletal muscle performance in both athletes and non-athletes. However, there are no reports on the effect of <it>B2BRK</it> 9-bp polymorphism on the response of the skeletal muscle to strength training, and our aim was to determine the relationship between the <it>B2BRK</it> SNP and triceps brachii functional and morphological adaptation to programmed physical activity in young adults.</p> <p>Methods</p> <p>In this 6-week pretest-posttest exercise intervention study, twenty nine healthy young men (21.5 ± 2.7 y, BMI 24.2 ± 3.5 kg/m²) were put on a 6-week exercise protocol using an isoacceleration dynamometer (5 times a week, 5 daily sets with 10 maximal elbow extensions, 1 minute rest between sets). Triceps brachii muscle volumes were assessed by using magnetic resonance imaging before and after the strength training. Bradykinin type 2 receptor 9 base pair polymorphism was determined for all participants.</p> <p>Results</p> <p>Following the elbow extensors training, an average increase in the volume of both triceps brachii was 5.4 ± 3.4% (from 929.5 ± 146.8 cm³ pre-training to 977.6 ± 140.9 cm³ after training, p<0.001). Triceps brachii volume increase was significantly larger in individuals homozygous for −<it>9</it> allele compared to individuals with one or two +<it>9</it> alleles (−<it>9</it>/-<it>9</it>, 8.5 ± 3.8%; vs. -<it>9</it>/+<it>9</it> and +<it>9</it>/+<it>9</it> combined, 4.7 ± 4.5%, p < 0.05). Mean increases in endurance strength in response to training were 48.4 ± 20.2%, but the increases were not dependent on <it>B2BRK</it> genotype (−<it>9</it>/-<it>9</it>, 50.2 ± 19.2%; vs. -<it>9</it>/+<it>9</it> and +<it>9</it>/+<it>9</it> combined, 46.8 ± 20.7%, p > 0.05).</p> <p>Conclusions</p> <p>We found that muscle morphological response to targeted training – hypertrophy – is related to polymorphisms of <it>B2BRK</it>. However, no significant influence of different <it>B2BRK</it> genotypes on functional muscle properties after strength training in young healthy non athletes was found. This finding could be relevant, not only in predicting individual muscle adaptation capacity to training or sarcopenia related to aging and inactivity, but also in determining new therapeutic strategies targeting genetic control of muscle function, especially for neuromuscular disorders that are characterized by progressive adverse changes in muscle quality, mass, strength and force production (e.g., muscular dystrophy, multiple sclerosis, Parkinson’s disease).</p

Arsenic-doped high-resistivity-silicon epitaxial layers for integrating low-capacitance diodes

An arsenic doping technique for depositing up to 40-?m-thick high-resistivity layers is presented for fabricating diodes with low RC constants that can be integrated in closely-packed configurations. The doping of the as-grown epi-layers is controlled down to 5 × 1011 cm?3, a value that is solely limited by the cleanness of the epitaxial reactor chamber. To ensure such a low doping concentration, first an As-doped Si seed layer is grown with a concentration of 1016 to 1017 cm?3, after which the dopant gas arsine is turned off and a thick lightly-doped epi-layer is deposited. The final doping in the thick epi-layer relies on the segregation and incorporation of As from the seed layer, and it also depends on the final thickness of the layer, and the exact growth cycles. The obtained epi-layers exhibit a low density of stacking faults, an over-the-wafer doping uniformity of 3.6%, and a lifetime of generated carriers of more than 2.5 ms. Furthermore, the implementation of a segmented photodiode electron detector is demonstrated, featuring a 30 pF capacitance and a 90 ? series resistance for a 7.6 mm2 anode area.Delft Institute of Microsystems and Nanoelectronics DimesElectrical Engineering, Mathematics and Computer Scienc

Improved RF Devices for Future Adaptive Wireless Systems Using Two-Sided Contacting and A1N Cooling

This paper reviews special RF/microwave silicon device implementations in a process that allows two-sided contacting of the devices: the back-wafer contacted silicon-on-glass (SOG) substrate-transfer technology (STT) developed at DIMES. In this technology, metal transmission lines can be placed on the low-loss glass substrate, while the resistive/capacitive parasitics of the silicon devices can be minimized by a direct two-sided contacting. Focus is placed here on the improved device performance that can be achieved. In particular, high-quality SOG varactors have been developed and an overview is given of a number of innovative highly-linear circuit configurations that have successfully made use of the special device properties. A high flexibility in device design is achieved by two-sided contacting because it eliminates the need for buried layers. This aspect has enabled the implementation of varactors with special Ndx -2 doping profiles and a straightforward integration of complementary bipolar devices. For the latter, the integration of AlN heatspreaders has been essential for achieving effective circuit cooling. Moreover, the use of Schottky collector contacts is highlighted also with respect to the potential benefits for the speed of SiGe heterojunction bipolar transistors (HBTs).Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc