Effect of plasma components on the feeding response of the mosquito Aedes aegypti L. to adenine nucleotides

ABSTRACT. The gorging response of Aedes aegypti to the ATP dissolved in platelet-poor plasma is greater than that of ATP dissolved in 0.15 m NaCl. The plasma components NaHCO₃ and albumin account for the full effect of the potentiation. Phosphate or tris buffers do not duplicate the bicarbonate effect. In 0.15 m NaCl with bicarbonate but lacking albumin the concentrations inducing 50% feeding are 58 μM ATP, 140 μM ADP, 460 μM AMP and 1500 μM cAMP. Non-adenine nucleotides such as ITP and GTP and phytic acid, and 2,3-diphosphoglyceric acid had no activity.     

Detection of potato virus Y in the aphid Myzus persicae by enzyme-linked immunosorbent assay (ELISA)

Potato virus Y was detected by enzyme linked immunosorbent assay (ELISA) in at least 50% of groups of five Myzus persicae. The mean A₄₀₅ value for groups of viruliferous aphids was 2–3 times greater than that for virus-free ones. PVY was not detected in Aphis craccivora, A. citricola or A. gossypii, three other species which transmitted the virus to peppers, and it was detected in only a small proportion of groups of Acyrthosiphon pisum. In a series of trials, success in detection of PVY by ELISA was not correlated with the ability of other aphids from the same source plant to transmit the virus to test plants. The limitation of ELISA for quantitative assay of PVY in aphids and for epidemiological work is discussed.     

Relative Time of Anthesis in Pistillate and Staminate Cucumber Flowers

Staminate (male) floral buds of cucumber plants reach anthesisat consecutive nodes of the main shoot at regular time intervals;however, pistillate (female) buds reach anthesis earlier thanmale ones, thus causing a marked deviation from the linear chronologicalsequence of male anthesia along the main shoot. Measured indays, this relative precedence of the female is greatest inwinter planting time, when short days and low temperatures causea shift towards femaleness in the whole plant, and it is smallestin late summer planting when environmental conditions favourmale tendency. There are also varietal differences in this respect—inone variety (Beth Alpha) the female precedes the male by a longerperiod of time than in another variety (Yorkstate Pickling).The position of the female flower on the main shoot does notseem to play an important role in this respect, but, as a rule,the precedence is greater for the first female than for thesecond or third female developing on the main shoot. It is suggested that the relative enhancement of one type ofsex organs (carpels) is a continuous process which determinesfirst the final sex type of the flower and later causes it toreach anthesis earlier.     

Hormonal Correlates of Paternal Care Differences in the Hylobatidae

Only one of the 15 species of monogamous hylobatids, the siamang (Symphalangus syndactylus), demonstrates direct paternal care in the form of infant‐carrying, providing a unique model for examining hormonal correlates of paternal care differences between siamangs and gibbons. We used behavioral data and fecal hormone analysis to investigate (1) differences in monthly percent father–infant proximity in relation to monthly fecal androgen metabolite concentrations from infant birth to the late postpartum period between siamangs and gibbons, (2) the pattern of change in fecal androgen and fecal estrogen metabolite concentrations during the 8‐week peripartum period between siamangs and gibbons, and (3) the change in mean fecal glucocorticoid metabolite concentrations at 1‐month postpartum from individual baseline between siamangs and gibbons. Father–infant proximity increased as androgen concentrations decreased over the postpartum period in siamangs but not in gibbons. Androgen concentrations increased around birth in siamangs during the 8‐week peripartum period, but exhibited a decreasing trend around birth in gibbons. Estrogen concentrations increased from pre‐ to postpartum in siamangs during the 8‐week peripartum period, but exhibited a decreasing trend from pre‐ to postpartum in gibbons. The difference in mean glucocorticoid metabolite concentrations from baseline was greater in siamangs than gibbons. Our data suggest a relationship between specific steroid hormone patterns and differences in paternal care among the hylobatids, warranting further investigation of such proximate mechanisms.     

Fine‐scale patterns of genetic divergence within and between morphologically variable subspecies of the sea urchin Heliocidaris erythrogramma (Echinometridae)

The spatial scale over which genetic divergences occur between populations and the extent that they are paralleled by morphological differences can vary greatly among marine species. In the present study, we use a hierarchical spatial design to investigate genetic structure in Heliocidaris erythrogramma occurring on near shore limestone reefs in Western Australia. These reefs are inhabited by two distinct subspecies: the thick‐spined Heliocidaris erythrogramma armigera and the thin‐spined Heliocidaris erythrogramma erythrogramma, each of which also have distinct colour patterns. In addition to pronounced morphological variation, H. erythrogramma exhibits a relatively short (3–4 days) planktonic phase before settlement and metamorphosis, which limits their capacity for dispersal. We used microsatellite markers to determine whether patterns of genetic structure were influenced more by morphological or life history limitations to dispersal. Both individual and population‐level analyses found significant genetic differentiation between subspecies, which was independent of geographical distance. Genetic diversity was considerably lower within H. e. erythrogramma than within H. e. armigera and genetic divergence was four‐fold greater between subspecies than among populations within subspecies. This pattern was consistent even at fine spatial scales (< 5 km). We did detect some evidence of gene flow between the subspecies; however, it appears to be highly restricted. Within subspecies, genetic structure was more clearly driven by dispersal capacity, although weak patterns of isolation‐by‐distance suggest that there may be other factors limiting gene exchange between populations. Our results show that spatial patterns of genetic structure in Western Australian H. erythrogramma is influenced by a range of factors but is primarily correlated with the distribution of morphologically distinct subspecies. This suggests the presence of reproductive barriers to gene exchange between them and demonstrates that morphological variation can be a good predictor of genetic divergence. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 578–592.     

HYDROPHOBIC LARVAL SHELLS: ANOTHER CHARACTER FOR HIGHER LEVEL SYSTEMATICS OF GASTROPODS

Higher level relationships within the Gastropoda are difficultto determine, in part due to the paucity of identified synapomorphiccharacters. Larval shell hydrophobicity may be a useful additionalcharacter for gastropod family systematics. A survey of 57 speciesindicates that larval shell hydrophobicity is common or ubiquitousin pyramidellids, opistho-branchs, and marine pulmonates butis unknown in patellogastropods, vetigastropods, and caenogas-tropods.The taxonomic distribution of hydrophobic larval shells is consistentwith the hypothesis that it is a heterobranch synapomorphy.Unfortunately the condition in key ‘lower’ heterobranchssuch as architectonicids and valvatoids is unknown. (Received 19 April 1996; accepted 8 January 1997)