Chromosomal polymorphism, morphometric traits and mating success in Leptysma argentina Bruner (Orthoptera).

The South-American species Leptysma argentina Bruner is polymorphic for a centric fusion between chromosomal pairs 3 and 6 (fusion 3/6). Cytogenetic and morphological studies revealed that fusion 3/6 significantly increases some morphometric variables in males. A selection components study showed that the fusion is positively selected for longevity, the direct effect being exerted on thorax height. Moreover, a unisexual approach revealed that sexual male selection acts by increasing third femur length. In the present study the effect of fusion 3/6 on morphometric variables and the effect of body size and karyotype on mating success in both males and females were analysed through a bisexual approach. Total body length (TL) and third femur length (FL) were significantly larger amongst the fusion carrier females. Besides, the largest females and the carriers of the fusion have increased mating success. The selection differential suggests that directional sexual selection favours the females with increased TL and fusion dosage; however, the selection gradient revealed that none of the variables here analysed is a direct target of sexual selection. The male sexual selection study agrees with previous results, showing the importance of the third pair of legs in male mating success among grasshoppers.

Distribution of IS900 restriction fragment length polymorphism types among animal Mycobacterium avium subsp. paratuberculosis isolates from Argentina and Europe.

Sixty-one Mycobacterium avium subsp. paratuberculosis isolates from cattle and deer from the Buenos Aires province, an important livestock region in Argentina, were typed by restriction fragment length polymorphisms (RFLP) analysis based on IS900. Four different RFLP patterns (designated 'A', 'B', 'C' and 'E') were identified in BstEII digests of genomic DNA. The most frequently observed type, pattern 'A', was found in 46 isolates (75%). The second, pattern 'E', included 8 isolates (13%), while the third, pattern 'B', included 6 isolates (10%). Pattern 'C' was found for only one isolate. All of the deer isolates were classified as pattern 'A', while cattle isolates represented all four RFLP patterns. Twenty-one isolates representing the four different BstEII-RFLP patterns were digested with PstI. Twenty isolates showed identical PstI-RFLP pattern. BstEII-RFLP patterns from Argentine cattle and deer were compared with patterns found in cattle, goat, deer, rabbit, and human isolates from Europe. The most common pattern in Argentina, pattern 'A', was identical to a less frequently occurring pattern R9 (C17) from Europe. The other Argentine patterns 'B', 'C' and 'E', were not found in the Europe. These results indicate that the distribution of M. avium subsp. paratuberculosis genotypes in the Buenos Aires province of Argentina is different from that found in Europe.