Close karyological kinship between the reptilian suborder serpentes and the class aves

Summary In contrast to the situation found in two classes of warm-blooded vertebrates, mammals and birds, the class Reptilia is not uniform with regard to total genetic content; rather, it contains two distinct categories. The close cytological kinship between snakes and birds was revealed. Both are almost identical in total genetic content, which is about 50 per cent that of placental mammals. Both have microchromosomes, as well as Z-chromosomes very similar in absolute size, comprising nearly 10 per cent of the homogametic haploid (AZ) set. This leads to the implication that snakes and birds originated from the same lineage, and that their Z-chromosomes have not changed substantially since the Jurassic period of the Mesozoic era, about 180 million years ago.Within the reptilian suborder Serpentes, the step-by-step differentiation from the primitive ZW pair to the grossly heteromorphic ZW pair could be observed. In the ancient family Boidae, the sex chromosomes were still homomorphic to each other. In the family Colubridae, the beginning of heteromorphism was manifested in two ways. In some species, a pericentric inversion on the W caused it to differ from the Z; in others, duplication of the W occurred. In the family Crotalidae, the W had apparently achieved its very specialized status; it was a distinctly smaller element.In Säo Paulo, this work was supported by Fundacão de Amparo a Pesquisa do Estado de São Paulo e Fundo de Pesquisas do Instituto Butantan. In Duarte, this work was supported in part by grant CA-05138-05, National Cancer Institute, U. S. Public Health Service. Contribution No. 36-64, Department of Biology, City of Hope Medical Center.     

ETUDE DES COMPLEXES DE PIGMENTS CHLOROPHYLLIENS D'EUGLENA GRACILIS AU COURS DE LA CROISSANCE ET A L'ETAT ADULTE

Une tude des cellules d'Euglnes et de leurs extraits prparsavec les ultra-sons, chauffs ou non chauffs (quelques heures 35), montre que:

1. le chauffage ne dtruit pas la chlorophylle de faon notable;
2. en prsence d'alcool, un agrgat de chlorophylle ayant unebanded'absorption 740–750 mµ apparait dans lesextraitsd'Euglnes ges de plus de 11 jours;
3. les jeunesEuglnes et les Euglnes ges et chauffes ne peuventformerl'agrgat absorbant aux grandes longueurs d'ondes;
4. deux outrois complexes chlorophylliens diffrents sont impliqusdansla formation des agrgats qui absorbent 740 mµ.

¹ Travail rendu possible par l'attribution d'une bourse d'tudede l'universit de Montral l'un des auteurs (DE K.) et l'octroid'une subvention de recherches (A-1196) du Conseil Nationaldes Recherches du Canada.     

Decomposition of cellulose in soils

1. Cellulose decomposition in forest and orchard soils was investigated by studying the breakdown of boiled and washed cellophane in the soils and in vitro. Decomposition occurred from quick to slow in the order: orchard on clay soil, forest on clay soil, forest on sandy loam, and in the latter in the order: calcareous mull, acid mull and mor. 2. In the different forest soils which were investigated the rate of decomposition was parallel to their water capacity. It slowed down considerably when the water content of the soil decreased, especially after the wilting point was reached. 3. Of the fungi isolated from these soils, those from orchard soil — 5% to 50%Fusarium spp. — were among the fastest decomposers of cellulose. This agrees with, and may explain the high rate of decomposition in orchard soil. 4. Decomposition in pure culture is quicker than in soil. As filtersterilized soil extract checked the decomposition in pure culture, but heat-sterilized soil extract did not, an extractable but heat-sensitive substance may be one retarding factor.