The distribution of oocyte 5S,somatic 5S and 18S + 28S rDNA sequences in the lampbrush chromosomes of Xenopus laevis

The nucleolus organizer locus of Xenopus laevis lampbrush chromosomes was identified by in situ hybridization of a ³H-labelled probe complementary to 18S + 28S rDNA. The nucleolus organizer is an axial granule on chromosome III that lies four-fifths the way down this chromosome reading from its larger (left) telomere, just within an exploded region that extends to its right end, where the lateral loops are exceptionally long. By in situ hybridization of ³H-labelled oocyte and somatic 5S spacer cRNA probes to similarly RNase-treated and denatured lampbrush chromosomes, the multiple sites of oocyte and somatic 5S gene families were identified. Oocyte 5S genes lie at the larger telomeres of the 15 chromosomes that possess these structures; that is, all but chromosomes X, XVII and XVIII. There are a further four sites, all peripheral, and in three of these, on chromosomes VII, X and XI, the sequences lie on lateral loops that are resolvable with the light microscope. By contrast all of the somatic 5S gene clusters occupy peripheral sites. There are two sites on chromosome III, one of which may be shared with oocyte 5S sequences; one on chromosome VII, which is very likely shared with oocyte 5S sequences; one terminal site on chromosome X; one site on chromosome XI that lies on a single pair of long loops which are inserted in a conspicuous and recognizable axial granule, loops which certainly carry oocyte 5S sequences too; two nearly terminal sites alongside the larger telomeres on chromosomes XII and XIV; and single interstitial sites on all three of the sphere-bearing chromosomes, VIII, IX and XVI. We suggest that 5S sequences on resolvable loops are transcribed by readthrough from upstream promoters, probably by polymerase II.     

Single women, voluntary childlessness and perceptions about life and marriage

42 single women who want to be childless, 18 who desire a 1 child family, and 42 who want 2 children responded to questions about the quality of their present lives and nature of future marriages. The groups of Australian women were closely matched for age and education, and on current quality of life there were few differences. They had similar levels of positive and negative affect, and described life as enjoyable, interesting, and contented. Those wanting to be childless, however, had rated life as less optimistic and less loving, and also as currently somewhat less satisfying, but life satisfaction was still quite high. These early deciders of childlessness, and those wanting only 1 child, wanted to be financially and socially more independent in future marriage type relationships than women wanting at least 2 children. They also expected to follow interests and careers to their fullest, wanted more role innovative partners, and were somewhat less concerned about home ownership, living to a budget, and keeping contact with family and friends. All women placed considerable importance on the need for trust, self-disclosure, and open communication in a relationship, although the voluntary childless rated more highly the need for intellectual stimulation and for each partner to be happy about the success of their mate. Compared to women wanting 2 children, those wanting to be childless expected a partner to perform a wide range of non-traditional roles in the home.     

Miridae of the genusTermatophylidea [Hemiptera] as predators of cacao thrips

Three species of the neotropical genusTermatophylidea are reported as predators of the cacao thrips,Selenothrips rubrocinctus (Giard), in Jamaica, Trinidad and Surinam. It is possible that these mirids are obligate predators and prey exclusively on thrips.