Production of alloantibodies against caprine lymphocyte antigens

In all, 217 primiparous goats were each injected with blood cells from their own newborn kid. Eighty-five goats were given mononuclear cells, 61 were given leucocytes and 71 received whole blood. The goats were injected one, two or three times before collection of sera. Sera were also collected from 42 non-injected, primiparous goats. The sera were compared with regard to their potential value in class I histocompatibility typing. The percentage of potentially valuable sera was highest in the group of animals injected twice with whole blood (66 X 7%). However, this percentage was not significantly higher than the percentage in the group of animals injected once with whole blood (54 X 7%). It is concluded that injecting primiparous goats once with whole blood from their own newborn kid, is a rapid and easy method, which gives a high yield of alloantisera with potential value in class I histocompatibility typing.     

Effect of Abscisic Acid on the Transpiration of Zea mays

Intact plants of Zea mays L. were treated with foliar sprays of cis-trans-abscisic acid (ABA) at concentrations from 10⁻⁹ to 10⁻⁴M. Even the lowest concentration caused a reduction of the transpiration rate as measured between 1 and 33 h after spraying. With increasing ABA concentrations, there was a nearly linear relationship between the logarithm of the ABA concentration and the (decreasing) transpiration rate within that period. Subsequently a partial recovery of the transpiration rate set in, beginning progressively later as the ABA concentration was increased. After 5 1/2 days the transpiration rate of plants treated with 10⁻⁹ and 10⁻⁸M was nearly back to normal, whereas plants treated with 10⁻⁴M transpiration at only about 2/3 their normal rate. In experiments with detached maize leaves supplied with water or ABA solutions (10⁻⁸ to 10⁻⁵M) through their cut bases, the transpiration of control leaves decreased gradually to a low level in 24 h. ABA caused a marked and rapid reduction of the transpiration rate compared to that of the controls. After a few hours, the transpiration of the treated leaves decreased at a slower rate than that of the controls, thus approaching the control values. After 35 h, the transpiration of leaves treated with 10⁻⁵M ABA was nearly the same as in untreated leaves. Exchanging the ABA solution for distilled water after 24 h had little effect on the subsequent course of the transpiration rate.     

Differences in the Responses to Water Stress of Growing and Non-Growing Regions of Maize Mesocotyls: Protein Synthesis on Total, Free and Membrane-Bound Polyribosome Fractions

The growing and non-growing regions of the mesocotyl of youngmaize seedlings show different responses to water stress withrespect to their ability to retain polyribosomes. The growingregion shows a marked reduction in total polyribosomes, althoughsome are retained within the stressed tissue. In the non-growingregion there is little stress-induced change to the total polyribosomecontent. These results support the contention that physiologicallyyounger, growing tissues are more sensitive to water stressthan more mature tissues that have ceased to grow. The free(FP) and membrane-bound (MBP) polyribosome content of the growingmesocotyl region is considerably greater than that of the non-growingregion, which is indicative of their more active metabolism.Both the MBP and FP fractions decline when the cells of thegrowing region are subjected to stress: no differential sensitivityis evident. Hence any qualitative changes in protein synthesisinduced by stress must be expected to result from changes inactivity of both polyribosome fractions. In the stressed non-growingregion, FP decline slightly, but MBP exhibit no consistent changes.     

A field technique for the determination of zooplankton grazing on natural bacterioplankton

SUMMARY. 1. A method for the determination of zooplankton community grazing rates on natural populations of bacteria is described.
2. Undisturbed zooplankton samples were incubated with ³H-thymidine-labelled bac teriioplankton, and animals and their food subsequently separated by size.
3. Prehandling of zooplankton by concentration before incubation reduce the grazing rates by a factor ranging from three to four.
4. Time series experiments showed that appropriate incubation periods ranged from 40 min at 14°C to 60 min at 10°C.
5. Spatial variability in the zooplankton was the main source of the overall standard error. This was considerably reduced by using composite samples.     

Cessation of Protein Synthesis in Water-Stressed Pea Roots and Maize Mesocotyls without loss of Polyribosomes. Effects of Lethal and Non-Lethal Water Stress

Pea roots and maize mesocotyl segments retain polyribosomeswhen subjected to mild and moderate water stress. Even underwater-stress conditions that are lethal, i.e. where there isno recovery of protein synthesis upon return to full hydration,some polyribosomes are retained. Therefore cessation of proteinsynthesis under water stress conditions is not due to the inabilityof cells to retain their polyribosomes. This observation contradictsseveral previous reports. The polynbosome content of PEG-stressedroots is lower, at equivalent water potentials, than that ofair-dried roots. We suggest that the capacity of a higher planttissue to withstand water stress cannot easily be correlatedwith its capacity to retain polyribosomes.     

Lymphocyte antigens in Norwegian goats: serological and genetic studies

Altogether, 292 goat alloantisera were screened for antilymphocyte reactivity in a two-step dye exclusion microcytotoxicity test. Fifteen different lymphocyte antigen specificities were characterized by cluster analysis and absorption studies. The specificities were designated N1-N15 (N for Norwegian). Lymphocytes from 247 Norwegian dairy goats were tested. Each animal displayed from none to four of the characterized specificities. Lysostrip testing and family studies indicated that the specificities N1-N14 were coded for by multiple alleles belonging to at least two closely linked loci. It is suggested that these loci are part of the caprine major histocompatibility complex. Family studies gave strong evidence that the specificity N15 was not coded for by genes located in the same region as the other 14 specificities. Absorption studies showed that this specificity was located on both lymphocytes and erythrocytes.     

SEDIMENTARY STRUCTURES IN CAMBRIAN LIMESTONES STUDIED BY RADIOGRAPHY

The paper deals with radiographic studies of Middle Cambrian 'fragment limestone', and Upper Cambrian anthraconite concretions from Bornholm (Denmark). A very simple method provides good insight into the sedimentary structures of the rocks and hence a good foundation for interpretation of the lithogenesis.