摘要:

Two types of NS cells were observed medially in the pars intercerebralis of the protocerebral lobes ofH. triangularis. They constitute a dorso-medial and a dorso-lateral group. According to the size and staining properties with PF and CHP they are classified as ‘A’ and ‘B’ type cells. ‘A’ cells are further classified into ‘A1’ and ‘A2’ types, according to the shape and size and staining characters with PF. Only a few ‘B’ type cells as a group in the tritocerebrum were noticed. ‘B’ type cells are more common than ‘A’ type cells in the aboral third of the ventral region of the sub-oesophageal ganglion. In the thoracic ganglion the cells are large in size and peripherally distributed.

ISSN:0373-4137    

DOI:10.1080/11250007809440138

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

We have examined the DNA content of spermatozoa from house mouse hybrids between ST 40 chromosome karyotype and Apennine populations with 22 chromosomes, as well as from hybrids between CD and CB strains both possessing 22 chromosomes, but characterized by dissimilar Robertsonian fusions. In the spermatozoa from 22 × ST 40 strains the variations in DNA content were found to fit the variability in gamete ploidy as estimated in spermatids by scoring second meiotic metaphase chromosomes. This demonstrates that during spermiohistogenesis aneuploid spermatids are not eliminated. The rare spermatozoa produced by CD×CB hybrids display a wide variability in their DNA content, with a low percentage of values referable to haploid cells.

ISSN:0373-4137    

DOI:10.1080/11250007809440139

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The diet of the tawny owl and the barn owl's, both dwelling in the Farma Valley (Tuscany) has been studied. These two strigiformes prey upon about the same micromammal species (which make up over 95% of their diets), although in different proportions. The barn owl is more microphagous than the tawny owl.

ISSN:0373-4137    

DOI:10.1080/11250007809440140

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The eukaryotic DNA is invariably in the form of a nucleoprotein complex called chromatin. The larger protein fraction in chromatin is made up of small basic proteins called histones. In the past the histones were generally considered the repressors of the transcriptional and replicative processes. Present opinion stresses their structural role in organizing the DNA molecules in chromatin fibres. The association of histones with DNA is not random and leads to an orderly, repetitive structure. Analysis by electron microscopy and by several other optical and biochemical techniques have demonstrated that chromatin is organized in subunits which have been called “P.S.” by Rill and Van Holde (1973), “v” bodies by Olins and Olins (1973, 1974) and nucleosomes by Oudetet al. (1975). These subunits are formed by an octamer of two molecules of each of the histones H2a, H2b, H3 and H4, associated with a string of 140 base pairs of DNA (which is especially resistant to nuclease digestion). The subunits are linked by a DNA segment (whose length varies in different cell types) associated with histone H1. The internal structure and spatial arrangement of the nucleosomes, their possible association with nonhistone proteins and the significance of the nucleosomal structure in chromatin during the replicative and transcriptional processes are discussed.

ISSN:0373-4137    

DOI:10.1080/11250007809440141

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

44 albino mice of SWISS strain, isolated for 21 days, 25 in the usual plexiglas laboratory cages, 19 in large complex boxes, were tested for aggressive behaviour both in a neutral arena and in their own territory. While mice isolated in usual conditions are similarly aggressive in their territory and in a novel area, the mice isolated in a large box are strongly aggressive in defending their territory and only mildly aggressive in a novel area. The hypothesis that a too restricted environment inhibits territory formation in mice is discussed.

ISSN:0373-4137    

DOI:10.1080/11250007809440142

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Colonial growth by blastogenetic budding in colonies ofBotryllus schlosserihas been studied in field and laboratory. It can be expressed either by the number of individuals making up the colony at the various blastogenetic generations or through growth rates defined as rn-1= Xn/xn-1= growth rate at generation (n — 1)th, where xnis the number of adult zooids of the n — th generation and xn-1that of generation (n — 1)th. This second method seems to be better.

ISSN:0373-4137    

DOI:10.1080/11250007809440143

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In posterior stumps ofDendrocoelum lacteum, after amputation at a level of the body in which the regeneration of the head cannot take place, the testicular follicles remain almost unaffected. This result is similar to that obtained by us inDugesia lugubrisin which, after resection of the posterior ventral nerve cords, the testicular follicles, posterior to the wound, remained almost unaltered.

ISSN:0373-4137    

DOI:10.1080/11250007809440144

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Satellite cells isolated from skeletal muscle of adult mice undergo a process of differentiation in culture.

ISSN:0373-4137    

DOI:10.1080/11250007809440145

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The net reproduction rate, the mean generation time and the intrinsic rate of natural increase have been measured at varying food supply in the marine CopepodTisbe furcata(Baird). The population response curve of the net reproduction rate is a monotonic increasing curve of the type Ro=RMexp — K √a, whereais the food quantity, RMthe maximum attainable reproduction and K a conversion coefficient. The mean generation time curve is a decreasing curve which tends asymptotically to a minimum. The plots of the curves show that small variations of food quantity in the low supply range result in a very significant reproductive variation, while large food variations in a higher supply range do not significantly affect the population reproductive capacity.

ISSN:0373-4137    

DOI:10.1080/11250007809440146

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In three groups of catfish, treated with testosterone at three different temperatures, the erythropoietic reaction was estimated by means of the percentage count of erythroblasts in hemopoietic organs. Testosterone has a stimulating action at temperatures of 20 °C and 24 °C, on the contrary it appears to be inactive at 14 °C.

ISSN:0373-4137    

DOI:10.1080/11250007809440147

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor