Territorial behaviour in southern impala rams (Aepyceros melampus Lichtenstein)

The role of territoriality was investigated by studying 25 impala rams at a reserve in the Waterberg region of South Africa (23°45′S, 28°23′E). Mean territorial tenure was 67.25 days (range 23–99), with a mean territory size of 21.0 ± 11.27 ha, compared with home ranges of 34.1 ± 9.03 ha for territorial rams and 58.8 ± 33.35 ha for bachelor rams, using the fixed kernel method. Territory boundaries remained constant, whilst the area surrounding important features such as water holes, appears to be neutral in terms of territoriality. The rut, as evidenced from peaks in chasing and roaring, lasted for 2 months from 10 April to 10 June 2001, with intensified behaviour including matings observed from 16 May to 4 June 2001. Territorial rams chase and roar more than bachelors. Flehmen and display behaviours are performed by all rams, whilst fights and other reproductive behaviours are generally rare. Bachelors browse more than territorial rams. Only bachelors spar and allogroom, and orally groom themselves more than territorial rams.     

Group differences in mean intelligence for the Dutch and Third World immigrants.

Evidence from eleven samples indicates that the mean IQ of third world immigrants in the Netherlands is lower than the Dutch mean by approximately one standard deviation for Surinamese and Antillians, and by approximately one and a half standard deviations for Turks and Moroccans. Since IQ tests provide the best prediction of success in school and organizations, it could be that the immigrants' lower mean IQ is an important factor in their low status on the Dutch labour market. The IQs of second-generation immigrants are rising.     

TWO TYPES OF CYTOPLASMIC CLEAVAGE IN THE COENOCYTIC SOIL ALGA PROTOSIPHON BOTRYOIDES (CHLOROPHYCEAE)1

Cytokinesis in the coenocytic green alga Protosiphon botryoides (Kütz.) Klebs was studied with transmission electron microscopy. In vegetative cells, nuclei with associated basal bodies and dictyosomes are scattered throughout the cytoplasm. Mature cells may develop either multinucleate resting spores (coenocysts) or uninucleate zoospores. Cytokinesis may be preceded by contraction of the protoplast due to the disintegration of vacuoles that are present in larger, siphonous cells. The formation of coenocysts in ageing, siphonous cells, is signalled by cleavage of the chloroplast and the development of arrays of phycoplast microtubules in one or more transversely oriented planes through the cell. Nuclei with associated basal apparatuses stay dispersed throughout the cytoplasm; the basal bodies apparently are not involved in organization of the phycoplast. The plasma membrane invaginates, resulting in a centripetal cleavage of the protoplast into two or more multinucleate daughter protoplasts. Simultaneously, wall material is deposited along the outside of the daughter protoplasts by dictyosome-derived vesicles, and finally two or more thick-walled coenocysts are formed. The formation of zoospores, on the other hand, is signalled by clustering of the nuclei in one or more groups depending on the shape of the mother cell. The nuclei become arranged with the associated basal apparatuses facing toward the center of the cluster. Bundles of phycoplast microtubules develop between the nuclei, radiating from the center of a cluster toward the plasma membrane; basal apparatuses or associated structures apparently are involved in organization of the phycoplast. Cleavage furrows grow out centrifugally along these bundles of micro-tubules, fed by dictyosome-derived vesicles. No wall material is deposited. An additional mitotic division occurs during cleavage, and finally numerous uninucleate, wall-less, biflagellate zoospores are formed. The ultrastructural features of the two different types of cytoplasmic cleavage associated with two different types of daughter cells have not previously been reported for chlorophycean algae.     

Unusual swimming mechanism in Calycopsis borchgrevinki (Hydrozoa)

Calycopsis borchgrevinki (Browne, 1910) from Antarctic waterswas studied histologically. The entire bell is enclosed in achitin-like skin, supported by chitin-like rods in the radialmesogleal fibres. In the tentacles a thick mesogloea is presentwithout chitinous structures. The gonads are embedded in thestomach folds. It is postulated that these characters are adaptationsto ecological conditions in Antarctic waters.     

Chromosomal locations of the gene coding for the CD3 (T3) γ subunit of the human and mouse CD3/T-cell antigen receptor complexes

The gene coding for the M _r 26000 chain of the human CD3 (T3) antigen/T-cell antigen receptor complex was mapped to chromosome band 11q23 by using a cDNA clone (pJ6T3 -2), by in situ hybridization to metaphase chromosomes and by Southern blot analysis of a panel of human-rodent somatic cell hybrids. The mouse homolog, here termed Cdg-3, was mapped to chromosome 9 using the mouse cDNA clone pB10.AT3 -1 and a panel of mouse-hamster somatic cell hybrids. Similar locations for the CD3 genes have been described previously. Thus, the corporate results indicate that the CD3 and genes have remained together since they duplicated about 200 million years ago.     

Zinc,copper, selenium,and glutathione peroxidase in blood of 11-yr-old dunedin,New Zealand children

Blood was obtained from 564 11-yr-old children who had participated since birth in a multidisciplinary health and development study. Serum zinc concentration did not differ between the boys and the girls (mean±SD: 91=17 μg/100 mL,n=453). Five-6% of serum zinc values were low; although there was a weak correlation with height, none of the boys with low values were below the 10th percentile for height for this group. Serum copper concentration (112±24 μg/100 mL,n=454) was unrelated to sex, height, weight, body mass index, socioeconomic status (SES), or iron status. Blood selenium concentration (49±10 ng/mL,n=564) was lower than previously reported for Dunedin children; it was higher in children in the lower SES categories. The data represent normal values for healthy, 11-yr-old NZ children.