The breeding biology of White-tailed Tropicbirds Phaethon lepturus at Cousin Island, Seychelles

During 1981–1983 the population of White-tailed Tropicbirds Phaethon lepturus at Cousin Island, Seychelles, bred aseasonally and asynchronously. The mean interval between consecutive successful breeding attempts was 273 days. Most individuals nested in the same site, and with the same partner, in successive attempts, but 7-5% of nest sites were used by more than one pair; 21 % of pairs which lost eggs, and 13% of those which lost chicks re-nested. Incubation lasted 40–41 days, with a mean incubation shift length of 6-6 days. Fledging periods varied between 67 and 89 days (mean 76-5 days). Mean fledging weight was not significantly greater than the average weight of breeding adults.
Fledging success was 36%. Many of the 39% of eggs which failed to hatch probably did so as a result of exposure to the sun's heat, following temporary desertion by adults which were themselves heat-stressed during incubation. Of the 41 % of chicks which died, most died young; many were probably killed by crabs Ocypode spp. Not more than 10% of all nest failures were due to nest site competition. A few chicks probably starved to death.
At the time of the study, both food and nesting sites were evidently in excess. A considerable increase in the size of the population will be possible before density-dependent control mechanisms begin to operate.     

The BULT Melanoma: A Spontaneous Transplantable Tumor in Mice

The BULT melanoma originated at Brown University as a spontaneous, small black nodule on the tail of an adult female mouse of the LT/Ch strain. Histological examination of a portion of the tumor indicated that it was intradermal and consisted predominantly of heavily melanized, ovoid to fusiform cells with melanin-laden macrophages scattered among them. The BULT melanoma has been maintained in LT/Ch mice for approximately 5 years by periodic transplantation, at first subcutaneously on the flanks and, more recently, intramuscularly in the hind legs. The shift in transplantation site was made following a marked decline in the growth of subcutaneous grafts. The transplants have retained the uniform deep-black melanization and general histology of the primary melanoma. Numerous melanosomes at all stages of development are found within the melanoma cells. DOPA-positive cytoplasmic vesicles are abundant. Occasional autophagic vacuoles containing clusters of melanosomes are also present. A few metastases from the transplanted melanoma have been observed in lymph nodes and on one occasion in the lungs. When grown in vitro, BULT melanoma cells do not require special growth promoting agents (e.g., TPA; cAMP) in order to proliferate. The BULT melanoma differs in one or more respects from each of the other three transplantable spontaneous mouse melanomas widely used in cancer research. In addition, it arose in a strain of mice characterized by the spontaneous death of melanocytes while the latter are engaged in synthesizing eumelanin within hair follicles. Karyotypic analysis of cultured cells showed a modal chromosome number of 68 with a range of 58–72 chromosomes.     

Responses of Cultured Melanocytes to Defined Growth Factors

To proliferate in vitro, normal melanocytes, unlike normal fibroblasts, require specific growth factors in addition to those supplied in serum. The substances that promote melanocyte proliferation, such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and stimulators of cyclic adenosine monophosphate (cAMP), also promote pigmentation. Consequently, cell division and expression of at least some differentiated functions are not mutually exclusive for melanocytes. At present, the only known natural growth factor that can replace TPA in normal human melanocyte cultures is basic fibroblast growth factor (bFGF). Like TPA, bFGF is effective, most of the time, only in the presence of added cAMP. Some preparations of bFGF, however, may have a highly labile, intrinsinc cAMP stimulatory activity. It is thus possible that bFGF can assume two forms, dependent on and independent of cAMP stimulatory activity. Alternatively, a second factor may exist in pituitary glands that co-purifies with bFGF but deteriorates with storage. Abnormal melanocytes in culture, such as those derived from dysplastic nevi and primary melanomas, depend on the specific factors (bFGF and cAMP), whereas melanocytes from metastatic melanomas do not     

A sporulation medium for Clostridium perfringens

A new solidified medium for inducing sporulation of Clostridium perfringens is described. The essential components of the medium are bile, bicarbonate and quinoline. The medium induced significant sporulation in all of 100 strains of Cl. perfringens isolated at random from human faecal specimens. The majority (94%) of strains sporulated profusely.     

Passive Haemagglutination Test for Anti-rhinovirus Antibodies

The use of chromic chloride as a coupling reagent has made it possible to coat red cells with rhinovirus protein. This is shown by immunofluorescence, electron microscopy and immunocolloidal experiments.     

Genetics and Molecular Biology of Mouse Pigmentation

The formation of mouse coat color is a relatively complex developmental process that is affected by a large number of mutations, both naturally occurring and induced. The cloning of the genes in which these mutations occur and the elucidation of the mechanisms by which these mutations disrupt the normal pigmentation pattern is leading to an understanding of the way interactions between gene products lead to a final phenotype.