Host Specialization and Dispersal in Avian Haemosporidians

In order to be able to understand the ecological and evolutionary processes involved in the emergence of infectious diseases, one needs to comprehend how parasites arrive at new geographical areas and how they manage to maintain viable populations and even expand their ranges. We discuss host specificity in avian haemosporidians and how encounter and compatibility filters affect the dispersal of avian haemosporidians, and how these filters affect avian haemosporidian assemblages at different spatial and evolutionary scales. There are at least three important barriers to the dispersal of avian haemosporidians: (i) geographic barriers, (ii) environmental barriers, and (iii) interspecies barriers. In this chapter, we discuss the factors involved in these barriers and their effects on the structure of avian haemosporidian assemblages. Host specificity plays an important role in parasite dispersal, and in the case of avian haemosporidians that are vector-borne parasites, it needs to be evaluated both at the vector and bird host levels. Understanding the effects of these factors on host–vector–parasite dynamics is important to unravel the dispersal and diversification mechanisms of avian haemosporidians. We end this chapter reviewing host specialization in avian haemosporidians of tropical regions, discussing the mechanisms involved in the dispersal and specialization of these parasites and point out important research gaps that need attention

Angiotensin-converting enzyme gene polymorphism, left ventricular remodeling, and exercise capacity in strength-trained athletes

The mechanisms that regulate the development of human physiological cardiac hypertrophy remain poorly understood. The renin-angiotensin system, which is modulated by genetic polymorphism, plays an important role in the regulation of vascular tone and myocardial hypertrophy. Although a few studies have analyzed the association of angiotensin-converting enzyme (ACE) polymorphism and left ventricular (LV) hypertrophy in isotonic exercise-trained subjects who developed eccentric cardiac hypertrophy, there has been no research done in power athletes who developed concentric cardiac hypertrophy. We have hypothesized that ACE genotypic modulation characteristics may affect LV mass in power athletes. This study included 29 elite Caucasian wrestlers ( mean age, 22.6 years) and 51 age-matched sedentary subjects. According to the absence or presence of the insertion segment in the polymerase chain reaction (PCR) product, the subjects were classified as homozygous deletion-deletion (DD), insertion-insertion (II), or heterozygous insertion-deletion ( ID). The association of LV hypertrophy with ACE gene insertion/deletion (I/D) polymorphism was analyzed. Left ventricular mass and index were determined by echocardiography. Angiotensin-converting enzyme genotyping was performed on peripheral leukocytes using the polymerase chain reaction technique. The study and control group subjects were similar in height and weight. Left ventricular hypertrophy in the athletes was more apparent than in the controls. Angiotensin-converting enzyme genotype II frequency was 17.2% (5) in the athletes, 17.6% (9) in the controls; ID frequency was 51.7% (15) in the athletes, 56.8% (29) in the controls; and the DD frequency was 31% ( 9) in the athletes and 25.4% ( 13) in the controls. Left ventricular mass and mass index were found to be higher in genotype DD (126.2 +/- 2.9 g/m(2)) than genotype II (85.5 +/- 4.0 g/m(2)) or genotype ID (110.1 +/- 2.3 g/m(2)) in the athletes ( P < 0.001). Furthermore, maximal oxygen consumption in genotype DD was found to be higher than in II and ID. An association was found between ACE gene I/D polymorphism and LV hypertrophy in strength-trained athletes

Effects of exercise on visual evoked potentials

PubMedID: 16051549The aim of this study was to investigate the effects of acute or habitual exercise on visual evoked potentials (VEP). The study group consisted of 9 female and 7 male volleyball players and the control group contained 9 female and 7 male students who were not involved in any sportive activity. The N75, P100, and N145 latency and amplitudes were measured before and after exercise. Intragroup comparison was made to evaluate the acute effects and intergroup comparison for the chronic effects of exercise. Significant differences were noted between athletes and the sedentary subjects in terms of pre-exercise left-N145 latencies and amplitudes and left -P100 amplitudes. Right-eye N145 latencies of inactive female subjects obtained before and after exercise were also statistically different. The results suggest that acute and habitual exercise affects the VEP responses independent from the body temperature and other physiological parameters. Small sized pre-exercise P100 amplitudes in the athletes can be attributed to the effect of rapid visual-activity-demanding sports on the central nervous system. Visual evoked potentials maybe used as neurophysiological criteria in defining the performance of an athlete. Copyright © 2005 Taylor & Francis Inc

Genetic Diversity and Identification of Palearctic Black Flies in the Subgenus Wilhelmia (Diptera: Simuliidae)

Accurate species identifications are the essential first step in understanding the medical, economic, and ecological importance of black flies. The utility of DNA barcoding based on cytochrome c oxidase subunit 1 (COI) sequences was evaluated for identifying six common species of Palearctic black flies in the subgenus Wilhelmia, including several that are virulent pests. Chromosomally identified larvae from Turkey and Germany and COI sequences in GenBank were analyzed. Intraspecific genetic divergence was 0.7-3.5% (mean 1.6%), whereas interspecific genetic divergence was 2.7-16.9%. On the basis of COI barcodes, the six nominal species of Simulium (Wilhelmia) were clustered in three distinct clades with high levels of genetic divergence, using maximum likelihood and Bayesian analyses. All specimens of Simulium equinum (L.), Simulium pseudequinum Seguy, and Simulium paraequinum Puri were correctly identified. However, >75% of identifications were ambiguous for Simulium lineatum (Meigen) and Simulium turgaicum Rubtsov (Meigen) because of overlapping intra-and interspecific divergence of the two species and Simulium balcanicum (Enderlein), all three of which are chromosomally similar and nearly isomorphic. Phylogenetic evaluation showed that S. balcanicum, S. equinum, S. pseudequinum, and S. paraequinum were monophyletic, with high bootstrap and posterior probability values, but it also showed that S. lineatum and S. turgaicum were paraphyletic, each clustering in two distinct groups, suggesting the presence of cryptic taxa. Although DNA barcoding provided a partialmeans of identification and indications of additional biodiversity, other- molecularmarkers are needed to clarify the limits of all pest species of the subgenus Wilhelmia