On the origins and genetic diversity of South American chickens: one step closer

Local chicken populations are a major source of food in the rural areas of South America. However, very little is known about their genetic composition and diversity. Here, we analyzed five populations from South America to investigate their maternal genetic origin and diversity, hoping to mitigate the lack of information on local chicken populations from this region. We also included three populations of chicken from the Iberian Peninsula and one from Easter Island, which are potential sources of the first chickens introduced in South America. The obtained sequencing data from South American chickens indicate the presence of four haplogroups (A, B, E and D) that can be further subdivided into nine sub‐haplogroups. Of these, four (B1, D1a, E1a(b), E1b) were absent from local Iberian Peninsula chickens and one (D1a) was present only on Easter Island. The presence of the sub‐haplogroups A1a(b) and E1a(b) in South America, previously only observed in Eastern Asia, and the significant population differentiation between Iberian Peninsula and South American populations, suggest a second maternal source of the extant genetic pool in South American chickens.     

The role of body size in mating success of Sphenarium purpurascens in Central Mexico

1. The effect of body size on the assortative mating and reproductive behaviour of the univoltine grasshopper Sphenarium purpurascens (Charpentier) was studied in Central Mexico. 2. Assortative mating by size was observed in the field. Evidence of positive assortative mating in relation to body size was found in laboratory experiments. Female fecundity and male success in contests were also correlated with body size. 3. Larger females had a higher number of eggs per pod. Larger males usually won fights and were able to take over females from other males, and to resist takeovers by other males while guarding. 4. Individuals of both sexes were observed copulating with more than one sexual partner in the field, suggesting polygamy. Male–male contests determined access to females, and males exhibited a postcopulatory prolonged mate-guarding behaviour lasting up to 18 days. 5. In a 2-year study, sex ratio was male-biased at the beginning of the reproductive season and decreased to 1:1 by the end of the season, suggesting that the population is protandrous. 6. The results of this study indicate that assortative mating results from male–male competition and female availability, and suggests that body size is a potential target of natural and sexual selection.     

Localization of dipeptidyl aminopeptidase yscIV in the plasma membrane of Saccharomyces cerevisiae

The subcellular distribution of dipeptidyl aminopeptidase activity was studied in protoplast lysates of Saccharomyces cerevisiae that were virtually free from vacuolar contamination. Dipeptidyl aminopeptidase yscIV, the STE13 gene product, was found to be associated with plasma membrane vesicles after sucrose gradient isopycnic centrifugation. Another dipeptidyl aminopeptidase activity, not yet fully characterized, was localized in a microvesicular population co-sedimenting with chitosomes.     

Yeast vacuolar aminopeptidase yscI. Isolation and regulation of the APE1 (LAP4) structural gene

The structural gene, APE1, (LAP4), for the vacuolar aminopeptidase I of Saccharomyces cerevisiae was cloned with the aid of a staining technique which permitted monitoring of aminopeptidase activity in yeast colonies. Genetic linkage data demonstrate that integrated copies of the cloned gene map to the APE1 locus. The nucleotide sequence of the cloned gene was determined. The open reading frame of APE1 consists of 514 codons and, therefore, encodes a larger protein (MW 57,003) than the reported mature aminopeptidase yscI (MW 44,800), suggesting that proteolytic processing must occur. A 1.75-kb mRNA, which is made in substantial amounts only when yeast cells have exhausted the glucose supply, was identified.