Aspects of the biology of Pilot whales (Globicephala melaena) in recent mass strandings on the British coast

Five mass strandings of Pilot whales, involving from 23 to 40 animals, occurred on the British coast between 1982 and 1985. The sex ratio in all strandings was biased towards females (62% overall), but more than one mature male was present in each group. A multi-male, polygynous social system is suggested. Growth is rapid from a mean body length at birth of 1.78 m to about 3 m at 2–3 years. Thereafter, males grow faster than females and attain a greater body length by some 18–25%. Maximum body lengths in this study were of a 6.3 m male and a 5.5 m female. The greatest ages determined were of a 20-year-old male and a 25-year-old female, but there is a possibility that readable dentine is not deposited in the teeth of older animals and that some whales are thus of a greater age than can be detected. Females become sexually mature at about seven years of age and a body length of 3–4 m. Some reach sexual senility before death. Males mature at a greater age and at about 5 m in length. Annual calf production is about 11% and no seasonality in parturition could be detected. Pollutant levels are generally within the range of those published for odontocetes, but PCB levels are higher than any yet found in other Pilot whale populations. Evidence of squid was found in three digestive tracts. Blubber thickness increases with the size of the animal, reaching 35–65 mm in adults. The existence of an annual, rigid north-south migrational pattern is unlikely.     

Critical Concentration of Tissue 9

Solution culture experiments with spring wheat (Triticum aestivumcv. Neepawa) showed that the critical phosphorus concentrationin the shoot (CPC) was lower when root temperatures were optimalfor growth. Root temperatures of 10, 15, 20 and 25°C wereused, the optimal was 25°C. The plants were sampled at definedstages, either at 4·0 g fr. wt. or with 6 mature leavesand the phosphorus (P) status of the plants at the samplingtime was evaluated by observing the responses of other plantsto an additional supply of P. These two precautions were criticalto the interpretation of the data and may explain the discrepancyin the literature about the relationship between plant growthrate and the CPC. Key words: Relative growth rate, Wheat     

Entrainment of Geotropic Oscillations in Hypocotyls of Heliunthus annuus– An Experimental and Theoretical Investigation

A theory for the geotropic movements of the Heliunthus unnuus hypocotyl has been given earlier by Johnsson et ul. In the present paper this theory is tested by extensive experiments. The magnitude as well as the rate of geotropic curvature are found to be in agreement with the theoretical predictions. Further, the geotropic reaction time, defined as the time between the start of geotropic stimulation and the start of the geotropic reaction is determined as a function of the stimulation angle with respect to the plumb line. A slight variation found in the reaction time is included in the theory.     

Differential Under-replication of Satellite DNAs during <Emphasis Type="Italic">Drosophila</Emphasis> Development

SATELLITE DNAs are heavily concentrated in the centromeric heterochromatin of metaphase chromosomes^1–3. Satellites and other repeated polynucleotide sequences are under-represented in the polytene, salivary gland cells of Drosophila melanogaster, D. virilis and D. hydei larvae but are fully represented in diploid cells from embryos and imaginal disks^4–6. This under-representation in polytene cells stems from the association of heterochromatin in the chromocentre and the progressive under-replication of the chromocentre during larval development^7,8.     

Transplantation Immunity in Annelids. III. Effects of Temperature on Xenograft Rejection in Earthworms

Earthworms are capable of destroying body wall xenografts. Xenograftstransplanted Eisenia foetidaLumbricus terrestris at varioustemperatures showed that graft survival time is inversely proportionalto temperature in both cases. Colder temperatures slow graftrejection, but higher temperatures, up to optimal limits, accelerategraft destruction. At 21 C, Eisenia grafts on Lumbricus hostsare rejected faster than at any other experimental temperature;the variability in individual times is lessened. Beginning at23 C sub-optimal conditions are approached. Thus, graft survivaltimes are more prolonged. Lumbricus grafts on Eisenia hostsare rejected most quickly at 23 C; at 27 C all Eisenia are dead.A review of the earthworm's general thermal dependence is presentedand a rationalization for prolonged second-set graft survival(negative memory) at low temperatures is given. Temperatureeffects probably account for the lack of positive memory at15 C from previous studies.     

Adaptations of Polygynous Breeding in the Bobolink, Dolichonyx oryzivorus

In some species of polygynous songbirds, males assist in feedingnestlings of their first (primary) female but ignore offspringof subsequent (secondary) mates. A number of adaptations importantin minimizing the disadvantages of a secondary status in femaleBobolinks (Dolichonyx oryzivorus) have been discovered. In Bobolinks, clutches of secondary females are significantlysmaller than those of primary females, thereby adjusting broodsize to correspond better with food delivery capabilities ofsecondary hens. Commencement of incubation with deposition ofthe penultimate egg allows additional brood size adjustment,for the resulting hatching asynchronism promotes efficient cullingof the late-hatching chick in times of food shortage, withoutendangering the entire brood. Secondary females differ fromprimary pairs in food exploitation techniques by capitalizingon insects found close to the nest and by showing less discriminationin food selection. Such behavior permits compensation in therate of food delivery trips to secondary nestlings so as toequal the tempo maintained by both members of the primary pair,yet results in quantitative disparities in food brought to primaryand secondary nestlings. Flexibility in male feeding responses,resulting in partial male assistance at secondary nests in situationswhere secondary brood size is exceptionally large, is also importantin helping to maximize the reproductive performance of birdsengaging in this mating strategy.     

Infection of stored celery plants by Centrospora acerina

Chlamydospores in tissue near the bases of plants and in attached soil particles were the main form of inoculum of Centrospora acerina (Hartig) Newhall found on celery plants prepared for storage. Most of these spores remained ungerminated for several weeks but subsequently formed germtubes, terminal appressoria and infection-pegs, which usually penetrated the plant surface through either the intact cuticle or damaged areas. For several weeks after the beginning of storage the plants were highly resistant to infection. During this time, appressoria failed to penetrate the intact cuticle and, if the fungus entered through damaged areas, hyphal growth in tissue was suppressed. Infection was often found to be associated with abrasion or splitting of the cuticle in commercially stored plants and, in experiments, deliberate damage enhanced the probability of infection. The development of the disease was much slower at 2 d?C than at 15 d?C.     

Studies on plant cuticle

The cuticles of plants of the Saxifragaceae, Rosaceae and Leguminosae are compared by chemical methods. Wide differences occur in the deposits of surface wax and cuticular membrane even within species of one genus. The relative proportions of four hydroxy-fatty acids in the cutin acids of plants of the families are assessed and the value of cutin analysis as a taxonomic criterion is discussed.     

A re-examination of the induction of phloem transfer cell development in pea leaves (Pisum sativum)

Abstract The development of phloem transfer cells in expanded dark grown leaflets of pea seedlings (Pisum sativum) has been re-examined. In agreement with previous observations transfer cells in leaflets maintained in the dark did not form wall ingrowths to the same extent as those placed in the light. A previous report that exposure to light in a carbon dioxide depleted atmosphere inhibited wall ingrowth formation could not be confirmed. It was found that dark grown leaflets could be induced to form wall ingrowths without illumination by immersing them in a glucose solution, demonstrating for the first time that light is not necessary for phloem transfer cell differentiation in leaves. Attempts were made to alter the carbohydrate level in the whole seedling by removing the cotyledons, but this had no recognizable effect on wall ingrowth formation in any of the treatments. Starch grain formation in the plastids was taken as an indication of available soluble carbohydrate level in the leaflets. It is concluded that both light and the presence of soluble carbohydrate can independently induce wall ingrowth formation in phloem transfer cells of pea leaflets.     

Inhibition of Cell Wall-Associated Peroxidase Isozymes with British Anti-Lewisite

Conditions were established for the use of British Anti-Lewisite(BAL) to inhibit preferentially the extracellular isoperoxidasesin pea stems. After a 2 h incubation period with 9.09 x 10⁴M BAL, approximately half of the activity of cell wall-associatedperoxidase was lost, while little inhibition of cytoplasmicenzyme was observed. Four isozymes from cell wall material wereidentified on starch gel e0lectrophoresis and stained with eugenol.Activity was tested with eugenol, ferulic and caffeic acids,and several redox dyes to probe the possible involvement ofthese isozymes in lignin biosynthesis. All isozymes had similarK_m values with eugenol and caffeic acid as compared to benzidine,a standard redox dye.