A population genetic study of the Banks and Torres Islands (Vanuatu) and of the Santa Cruz Islands and polynesian outliers (Solomon Islands)

As part of a multidisciplinary survey of populations in the Banks and Torres Islands of Vanuatu and the Southern and Central Districts of the Solomon Islands, nearly 2,400 persons have been tested for ABO blood groups and a number of serum protein and red cell enzyme genetic marker systems. For the ABO system, the populations are characterized in general by high gene O and low gene B frequencies except in two of the Polynesian Outlier Islands, Rennell and Bellona, which have high frequencies of B. Among the serum proteins, several alleles have distributions indicating significant movement of people between islands. These include Albumin ^{New Guinea} and the transferrin alleles Tf, and Tf, and Tf. Similar specific alleles for red cell enzymes also show distributions reflecting interisland population movement as well as contact with persons from outside the southern Pacific region. Examples are ACP in the acid phosphatase system, PGM and PGM, PGM and PGM, PGK⁴ and also HbJ^Tongariki. The data available for 11 polymorphic systems were used to generate genetic distances. Of the four Polynesian Outlier Islands, Anuta is most remote genetically, with Rennell and Bellona also relatively isolated. The fourth Polynesian Outlier, Tikopia, occupies a position genetically close to the Melanesian populations of the Banks and Torres Islands and the southern Solomons. The history of early European contact and voyaging in the Pacific, as well as archaeological and linguistic evidence and local legends, indicate that significant movements of people occurred between islands and provided opportunities for genes to be introduced from Europeans, Africans, and Asians. The genetic marker studies give evidence for genes from all these sources, though at a low level. Despite this admixture, the Polynesian Outlier and Melanesian populations have preserved their own distinctive genetic patterns.     

Effects of storage on microbial loads of two commercially important shellfish species, Crassostrea virginica and Mercenaria campechiensis.

The effects of storage on the microbial load in two commercially important species of shellfish were examined. Oysters (Crassostrea virginica) were stored as shellstock, shucked meats, and fully processed meats at four temperatures for up to 21 days, and clams (Mercenaria campechiensis) were stored only as shellstock. The concentrations of most microbiological groups of organisms increased with the duration and temperature of storage in both shellfish species, although the increases were significantly lower in claims. Concentrations of Vibrio cholerae rose by approximately 1 log in oysters stored as shellstock after 7 days at 2 degrees C, and Lac+ vibrios increased 2 logs at 8 degrees C. Total counts of bacteria, fungi, coliforms, fecal streptococci, Aeromonas hydrophila, and clostridia were significantly higher in shucked oysters than in those stored as shellstock. Fecal coliforms were statistically the same, but V. cholerae, Vibrio parahaemolyticus, and the Lac+ vibrios were higher in oysters stored as shellstock. The concentrations of all microbial groups were higher in fully processed oysters than in shucked meats, with the exception of the vibrios, which showed no significant difference among the treatments. The results showed that although traditional methods of storing shellfish resulted in an overall increase in the microbial load, vibrio levels increased only in oysters stored as shellstock. Although fecal coliform and total bacterial counts did not correlate with those for vibrios in fresh oysters, strong correlations were observed in oysters stored for 7 days, suggesting that these indicators may be useful in monitoring oyster quality when meats are stored for a limited time as shellstock.     

Relationship among fecal coliforms, Escherichia coli, and Salmonella spp. in shellfish.

The relationship of fecal coliforms, Escherichia coli, and Salmonella spp. was examined in freshly harvested and stored shellfish. In 16 of 40 freshly collected oyster samples, fecal coliform levels were above the recommended wholesale level suggested by the National Shellfish Sanitation Program (less than or equal to 230/100 g), and Salmonella spp. were present in three of these samples. Salmonella spp. were not, however, present in any sample containing less than 230 fecal coliforms per 100 g. Analysis of the data suggests that low fecal coliform levels in both fresh and stored oysters are good indicators of the absence of Salmonella spp., but that high levels of fecal coliforms are somewhat limited in predicting the presence of Salmonella spp. E. coli levels correlated very strongly with fecal coliform levels in both fresh and stored oysters and clams, suggesting that there is no advantage in replacing fecal coliforms with E. coli as an indicator of shellfish quality.     

Mechanics of gliding in birds with special reference to the influence of the ground effect

A model of the mechanics of gliding without loss of altitude (horizontal gliding) is developed. The model can be employed to assess the influence of the principal drag components (induced, profile and parasite drag), choice of initial and final glide velocities and height above the ground on glide distance. For birds gliding near to the ground the ground effect acts to decrease the induced drag and increase the lift to drag ratio of the wings. Minimum drag speed is reduced for birds gliding near to the ground. The model is applied to the gliding flight of the black skimmer (Rhyncops nigra). Glide distances for given initial and final velocities are significantly increased in the influence of the ground effect over out of ground effect values.     

Gibberellins and Heterosis in Maize : II. Response to Gibberellic Acid and Metabolism of [H]Gibberellin A(20)

Two maize inbreds, CM7 and CM49, and CM7 × CM49, their F₁ hybrid (which displayed significant heterosis), were examined with regard to response to exogenous gibberellin A₃ (GA₃), and in their ability to metabolize GA₂₀, a native GA of maize. The leaf sheath elongation response to GA₃ was far greater for the imbreds than for their hybrid. The inbreds also displayed significant elongation of the leaf blades in response to GA₃, whereas the hybrid was unaffected. Promotion of cell division in the leaf sheath of CM7 and the hybrid was effected by GA₃, but no promotion of cell elongation was observed in CM49, even though significant leaf sheath elongation occurred. Shoot dry weight of both inbreds was significantly increased by GA₃, but response by the hybrid in this parameter was slight and variable. Root dry weight of CM7 was significantly increased by GA₃, but was unchanged in CM49 and the hybrid. Thus, inbred shoot dry weight increases effected by GA₃ were not at the expense of the root system. Rapid metabolism of [2,3-³H]GA₂₀ occurred in all genotypes, although genotypic differences were observed. The hybrid had the highest rates of metabolism to GA glucosyl conjugate-like substances. Oxidative metabolism was also fastest in the hybrid, followed by CM7, and slowest in CM49, the slowest-growing inbred. Thus, rate of GA₂₀ metabolism is under genetic control in normal (i.e. not dwarfed) maize genotypes. These results, taken together with previous reports that the hybrid has significantly enhanced levels of endogenous GA-like substances, suggest that GA play a role in the expression of heterosis in maize.     

Effects of anoxia and flooding on alcohol dehydrogenase in roots of Glyceria maxima and Pisum sativum

Flood tolerant Glyceria maxima and intolerant Pisum sativum were compared in respect of the effects of anoxia and flooding on the maximum catalytic activities of alcohol dehydrogenase in their roots. Small (<73%) increases in enzyme activity occurred when excised roots of both species were incubated in nitrogen for up to 2 days. Further incubation in nitrogen rapidly and permanently damaged the roots of both species. Enzyme activity in flooded roots of Glyceria was about double that in corresponding non-flooded roots. A marginally greater difference was found for roots of Pisum. It was concluded that the two species respond so similarly to the above treatments that variation in the extent of induction of alcohol dehydrogenase is unlikely to be a significant factor in determining their ability to tolerate flooding.     

Relation of some M1 characters to the frequency of M2 mutants inArabidopsis thaliana

The relation of the M₁ root length and the frequency of M₁ chlorophyll chimeras to the sterility grade and to the frequency of M₂ mutants ofArabidopsis thaliana is demonstrated.     

A PLUCHEA HYBRID FROM THE PACIFIC

Two species of Pluchea have been introduced into the Hawaiian Islands in the present century. These are P. indica, native to southeastern Asia, and P. odorata, native to the western hemisphere. Both are erect shrubs. Within the past 30 years a third Pluchea taxon, a sprawling shrub morphologically distinct from the two species, has appeared in the Hawaiian Islands and on other islands in the tropical Pacific. On the basis of morphology, fertility, meiotic behavior, and other evidence, it is concluded that the third taxon is a hybrid between the two species. The hybrid is highly sterile; it has a limited capacity for asexual reproduction. Metaphase I configurations for both species were found to be 10_II; the most frequent configuration in the hybrid was 8_II + 4_I. The hybrid is given a binomial.