An Examination of the Value of 14C-urea as a Source of 14CO2 for Studies of Assimilate Distribution

Twenty-four hours after leaf 3 of a plant of Lolium multiflorumLam, was supplied with a droplet of ¹⁴C-urea and the plant enclosedin a polyethylene bag with an untreated plant, there were significantamounts of radiocarbon recovered from the untreated plant. Theleaf treated with ¹⁴C-urea was the major source of ¹⁴C leakagebut significant losses were also recorded from other parts ofthe plant. Reducing the humidity within the bag decreased theamount of ¹⁴CO₂ which escaped. Losses of radiocarbon from CO₂-treated plants were very low compared with those from urea-treatedplants but the pattern of assimilate distribution within thetwo types of plants was very similar. The possible causes ofthese effects are considered and the usefulness of ¹⁴C-ureaas a source of ¹⁴CO₂ discussed.     

EVALUATION OF BITTERNESS AND ASTRINGENCY OF (+)-CATECHIN AND (-)-EPICATECHIN IN RED WINE AND IN MODEL SOLUTION

Two stereoisomeric phenolic compounds, (+)-catechin and (-)-epicatechin, were rated for perceived intensity of oral astringency and bitterness by trained judges using the scalar method. Mouth drying and mouth roughening were also assessed, since they are often associated with astringency. Amounts of 375, 750 and 1500 mg/L of each compound were tasted in red wine, and in a model system, similar in composition to a dry table wine. Preliminary tests showed that these concentrations were above the threshold level but within the range found in wine. A control sample (model solution or wine without the addition of the above phenolic compounds) was also evaluated. The results showed that the two compounds were both bitter and astringent. The high (-)-epicatechin concentration was significantly more bitter and astringent than the equal concentration of (+)-catechin in the model solution. Mouth drying and roughening ratings showed a similar increasing pattern with the ratings of astringency particularly at the higher concentrations. However, these attributes were rated differently from astringency suggesting that although they contribute to astringency, they are not subsumed by it.     

A comparison of queen oviposition rates from monogyne and polygyne fire ant, Solenopsis invicta, colonies

Abstract. The oviposition rate of individual queens of Solenopsis invicta Buren (Hymenoptera: Formicidae) in relation to their weight and number of queens present in the colony was investigated by direct 2 h observations. There is a strong positive correlation between the weight of a queen and its oviposition rate in both monogyne and polygyne colonies. However, the number of eggs laid per mg queen is higher for moonogyne queens than for polygyne queens. This difference is more evident when the total weight of queens present in a colony is considered. The individual queen oviposition rate is negatively correlated with the number of queens in the colony. In addition, the weight loss per egg laid is significantly greater for polygyne than for monogyne queens, probably due to differences in egg size. These data suggest that oviposition is more efficient in monogyne than in polygyne queens at the individual level; however, at the colony level, polygyne colonies produce significantly more eggs. Comparison of colony level efficiency predicts that polygyne colonies must have at least nine queens to compete reproductively with a mature monogyne queen. Therefore, oligogyny does not appear to be a viable strategy for S.invicata.     

Performance of carbendazim formulations injected for the control of Dutch elm disease

Formulations of carbendazim, containing varying mineral acid concentrations, injected into elm trees were evaluated for their protectant and eradicant activities against Dutch elm disease. Those with high acid contents were the best protectants but none was entirely successful as an eradicant. The distribution of carbendazim within elm trees was erratic and there was a large fall-off in available fungitoxicant within the twigs 55–97 days after injection.     

Biology and ecology of three species of Australian Dragonets (Pisces: Callionymidae)

Callionymus sublaevis, C. calcaratus and C. calauropomus collected from Moreton Bay and offshore Queensland, were studied biologically and ecologically and the findings compared with other callionymid fishes from Australian waters and other areas. Predominant preys types included penaeid prawns, pelecypods and poly-chaetes. Differences in temporal feeding intensity and prey types eliminated competition in some cases. Through brain pattern analyses, these callionymids were shown to be predominantly sight feeders even at depth, although gustatory feeding also increased slightly with depth. Sex ratios in C. sublaevis were almost even, while C. calauropomus had a predominance of males. C. calcaratus had a predominance of females, but considerable variation occurred on a seasonal basis. Although considerable variation was found in spawning times and spawning period length, the histological changes that occurred in the development of oocytes was similar. The ovarian cycle in C. sublaevis was studied in detail and found to be typical of most teleosts. Length-weight regression coefficients in all species were significantly higher than 3.0, indicating that the weight increased faster than the cube of their length. In all cases females were heavier in older fish with the least difference in length-weight occurring between the males and females of C. calcaratus. Otoliths were found to be satisfactory and reliable for use as a method for age and growth determinations in two of the callionymids studied. Overlap of age groups was found in all species and this was mostly attributed to the length of spawning period. The dragonets studied here all reached age group IV+ and attained maturity usually by the second year. No evidence was found to indicate that males die after spawning as has been shown in C. lyra. Observations on predation by benthic piscivorous fishes and by one avian predator are reported.     

Studies in vitro and in vivo with powdery mildew fungicides

Droplets of 4-(i-cycloalkylalkyl)-2,6-dinitrophenols often protect areas of leaf very much greater than that of the initial deposit against powdery mildew. For a given alkyldinitrophenol, this type of protection is greater on apple than on marrow leaves. This zonal protection is not correlated with vapour activity in vitro or in vivo, or with inhibition of conidial germination in vitro, but is correlated with the degree of protection obtained when leaves are sprayed to give good cover. By contrast, crotonic esters of these alkyl-dinitrophenols do not show zonal activity, but nevertheless often exhibit protectant activity comparable with that of the parent phenols. These results suggest that exploitation of favourable hydrogen bonding characteristics in the fungicide molecule may lead to better control of fungal diseases in the field as a result of enhanced movement of fungicide in or on the leaf cuticle (zonal movement) or easier penetration of the fungal conidium.     

Observations on thermoregulation in the western slender glass lizard, Ophisaurus attenuatus attenuatus (Sauria: Anguidae)

Based upon thermocouple implantation, thermal preferenda and voluntary maxima for the head and body were studied in three individuals of Ophisaurus attenuatus attenuatus collected in Texas. Calculated grouped data for the head and body mean preferred temperature were 31.2°C (range 29.O° -34.7°C) and 31.8°C (range 30.3° -34.5°C) respectively. Gaping or panting were found to be absent in the O. a. attenuatus examined in this study.     

Dolphin swimming–a review

Research into dolphin swimming has historically been guided by false assumptions of 'effortless', 'high-speed' swimming. These assumptions have instigated the development of drag-reduction hypotheses but tests of these hypotheses have generally had little success. The autecological approach has dominated recent efforts and has been more successful. In this review we summarize results of decades of research efforts to study these creatures. (1) Drag is minimized primarily by the streamlined shape of the body and appendages, with no known contributions from compliant dampening, dermal ridges, secretions, boundary layer heating, or skin folds. All indications are that the boundary layer is turbulent. (2) Muscles for the upstroke and downstroke of swimming dolphins provide approximately equal power. (3) Output force is enhanced by insertions occurring on the long processes of the vertebrae and on the subdermal connective tissue sheath. (4) Measured swimming speeds are lower than previously believed, with maximum reported routine speeds being approximately 3 m/s. (5) Porpoising behaviour appears to be the most energetically conservative manner in which to breathe when swimming at high speed. (6) Riding surf and wind waves involves the balance between the wave slope and the weight of the animal whereas riding the bow wave involves the interaction of the pressure wave in front of a ship and the drag of the dolphin.