The occurrence and frequency of 2n pollen in 2x, 4x,and 6x wild,tuber-bearing Solanum species from Mexico,and Central and South America

Summary The occurrence of 2n pollen-producing plants was investigated in 187 plant introductions (PIs) of 38 wild species of tuber-bearing Solanum. These 2x, 4x, and 6x species are from Mexico, and Central and South America. The determination of 2n pollen-producing plants was conducted using acetocarmine glycerol. Plants with more than 1% large-size pollen were regarded as 2n pollen-producing plants. 2n pollen-producing plants were identified in the following species: 10 out of 12 Mexican 2x species, seven of nine South American 2x species, seven of seven Mexican and Central American 4x species, five of five South American 4x species, and five of five Mexican 6x species. The frequency of 2n pollen-producing plants varied among species at the same ploidy level, but the range of frequency, generally between 2 and 10% among species, was similar over different ploidy levels. The general occurrence of 2n pollen in both 2x and polyploid species, which are evolutionarily related, is evidence that the mode of polyploidization in tuber-bearing Solanums is sexual polyploidization. Furthermore, the frequencies of 2n pollen-producing plants in autogamous disomic polyploid species were not markably different from those of their related diploid species. It is thought that the frequent occurrence of 2n gametes with autogamy tends to disturb the fertility and consequently reduce fitness of polyploids. Thus, we propose that the breeding behavior of polyploids and the occurrence of 2n gametes may be genetically balanced in order to conserve high fitness in polyploid species in tuberbearing Solanum.Paper No. 3114 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc.     

Actualización en el manejo de la degeneración macular asociada a la edad

Age-related macular degeneration is the leading cause of legal blindness in people over 50 in developed countries. It is a multifactorial disease resulting from the interaction of genetic and environmental factors, and the age is the only worldwide admitted risk factor. The socioeconomic impact of the disease reaches enormous proportions, if we take into account the high cost of the available antiangiogenic therapy, the strict schedule of medical visits that it requires, and the impairment that it gives rise to. The response to treatment and the visual outcomes improve with early management of the retinal lesions, thus the early diagnosis of the disease in its initial phases, based on self-control with an Amsler grid and with regular ophthalmologic assessments, is essential.     

Relocation,consolidation, and settlement pattern in the Canadian subarctic

The relocation and consolidation of subarctic native populations into settlement patterns designed according to southern, urban models has often resulted in cultural confusion and an increase in interpersonal tension, alcohol abuse, and violence. Through a review of selected case material, and the detailed examination of one relocated community, the dynamics of this situation are highlighted. Where native communities have re-established themselves beyond the reach of government planners, the recreation of more culturally appropriate settlement patterns has ensued.     

Semen cryopreservation in golden‐headed lion tamarin,Leontopithecus chrysomelas

Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, susceptibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins.     

Conformist learning in nine-spined sticklebacks' foraging decisions

Theoretical analyses have reported that in most circumstances where natural selection favours reliance on social learning, conformity (positive frequency-dependent social learning) is also favoured. These findings suggest that much animal social learning should involve a copy-the-majority strategy, yet there is currently surprisingly little evidence for conformist learning among animals. Here, we investigate this possibility in the nine-spined stickleback (Pungitius pungitius) by manipulating the number of demonstrator fish at two feeders, one rich and one poor, during a demonstration phase and evaluating how this affects the likelihood that the focal fish copy the demonstrators'' apparent choices. As predicted, we observed a significantly increased level of copying with increasing numbers of demonstrators at the richer of the two feeders, with copying increasing disproportionately, rather than linearly, with the proportion of demonstrators at the rich foraging patch. Control conditions with non-feeding demonstrators showed that this was not simply the result of a preference for shoaling with larger groups, implying that nine-spined sticklebacks copy in a conformist manner.     

Chroococcopsis epiphytica n. sp., eine neue Cyanophycee aus dem Gebiet des Neusiedler Sees

The morphology and life history ofChroococcopsis epiphytica nova spec. is described, a German and Latin diagnosis is added. Cultivated plants display some differences in comparison with plants in their natural habitat: calcification occurs only in the natural medium, endosporangia are developed only by cultivated plants. At the basis, where single cells and thalli are attached, a special sort of jelly is produced; it is discernible only by elective staining with methylene blue. The systematic position of the new species is discussed.