Subsidiary cells in the Orchidaceae: their general distribution with special reference to development in the Oncidieae

Subsidiary cell formation in leaves of the Oncidieae begins with the production of a trapezoid cell on each side of the guard cell mother cell. The trapezoid cells are formed by oblique divisions in the tiles of cells next to the tile of cells containing the guard cell mother cell. The trapezoid cell usually divides unequally to form a subsidiary cell and a derivative cell. The subsidiary cell is smaller and next to the guard cell mother cell. The derivative cell enlarges and is often indistinguishable from the other epidermal cells. Rarely, polar subsidiary cells are also formed. In very rare cases the smaller of the division products of the trapezoid cell divides to form two subsidiary cells next to each guard cell. Subsidiary cells have been found in all tribes of the epidendroid and vandoid groups, all neottoid tribes examined except the Orchideae, and the subfamily Cypripedioideae. The absence of subsidiary cells in primitive genera of the epidendroid tribes and the presence of subsidiary cells in the most advanced genera of the epidendroid and vandoid groups supports the hypothesis that the presence of subsidiary cells is an advanced condition in the Orchidaceae.     

Resistance to Water Absorption in Germinating Rapeseed (Brassica napus L.)

Dynamics of the imbibition phase of rapeseed (Brassica napusL.) was studied by evaluating water content-water potentialrelations and the permeability to water. It was found that resistanceto water absorption was very high (diffusivity was very low)during the early stages of water absorption. As seed water contentincreased, resistance decreased by more than six orders of magnitude. The concept of hydraulic conductivity of a seed was introduced.The change in hydraulic conductivity with change in seed watercontent was similar to that observed for diffusivity. It wasshown that at late stages of water absorption hydraulic conductivityapproached values found in soils at the dry end of the availablewater range. For this reason it was suggested that hydraulicconductivity in soil may have an influence on imbibition ratein the late stages of water absorption.     

Active Calcium Transport by Plant Cell Membranes

The cytosolic free calcium concentration of higher plant cellsis maintained at about 01 µM by the action of membranecalcium transporters. These act to remove calcium from the cytosoland expel it to the apoplast or accumulate it in intracellularstores. In this review, the properties and subcellular localizationsof these systems are described. The major calcium transporterof the plasma membrane is a calcium pumping ATPase which showsmany similarities to its equivalent in mammalian cells. Thetransporter has been purified from maize coleoptiles and isof M_r 140 000, binds (and is activated by) calmodulin and showscommon antigenicity with the mammalian protein. Higher plantendoplasmic reticulum also contains a calcium pumping ATPasewhich transports calcium from the cytoplasm and its role andproperties, together with those of the tonoplast calcium/protonantiporter are presented. Evidence for calcium accumulationby chloroplasts and mitochondria is considered. The review alsodeals with the regulation of plant cell membrane calcium transportand its role in providing intracellular pools of calcium forsignal transduction. Key words: Plant, calcium transport, ATPase, cell membrane, calmodulin     

A lethal ovitrap‐based mass trapping scheme for dengue control in Australia: II. Impact on populations of the mosquito Aedes aegypti

In Cairns, Australia, the impacts on Aedes aegypti L. (Diptera: Culicidae) populations of two types of ‘lure & kill’ (L&K) lethal ovitraps (LOs), the standard lethal ovitrap (SLO) and the biodegradable lethal ovitrap (BLO) were measured during three mass‐trapping interventions. To assess the efficacy of the SLO, two interventions (one dry season and one wet season) were conducted in three discrete areas, each lasting 4 weeks, with the following treatments: (i) SLOs (>200 traps, ∼4/premise), BG‐sentinel traps (BGSs; ∼15, 1/premise) and larval control (container reduction and methoprene treatment) and (ii) larval control alone, and (iii) untreated control. Female Ae. aegypti populations were monitored for 4 weeks pre‐ and post‐treatment in all three areas using BGSs and sticky ovitraps (SOs) or non‐lethal regular ovitraps (ROs). In the dry season, 206 SLOs and 15 BGSs set at 54 and 15 houses, respectively, caught and killed an estimated 419 and 73 female Ae. aegypti, respectively. No significant decrease in collection size of female Ae. aegypti could be attributed to the treatments. In the wet season, 243 SLOs and 15 BGSs killed ∼993 and 119 female Ae. aegypti, respectively. The mean number of female Ae. aegypti collected after 4 weeks with SOs and BGSs was significantly less than the control (LSD post‐hoc test). The third mass‐trapping intervention was conducted using the BLO during the wet season in Cairns. For this trial, three treatment areas were each provided with BLOs (>500, ∼4/premise) plus larval control, and an untreated control area was designated. Adult female Ae. aegypti were collected for 4 weeks pre‐ and post‐treatment using 15 BGSs and 20 SOs. During this period, 53.2% of BLOs contained a total of 6654 Ae. aegypti eggs. Over the intervention period, collections of Ae. aegypti in the treatment areas were significantly less than in the control area for BGSs but not SOs. An influx of relatively large numbers of young females may have confounded the measurement of changes in populations of older females in these studies. This is an important issue, with implications for assessing delayed action control measures, such as LOs and parasites/pathogens that aim to change mosquito age structure. Finally, the high public acceptability of SLOs and BLOs, coupled with significant impacts on female Ae. aegypti populations in two of the three interventions reported here, suggest that mass trapping with SLOs and BLOs can be an effective component of a dengue control strategy.     

Characterization of microsatellites for parentage studies of white‐throated magpie‐jays (Calocitta formosa) and brown jays (Cyanocorax morio)

White‐throated magpie‐jays (Calocitta formosa) and brown jays (Cyanocorax morio) are cooperative breeders that live in complex groups composed of helpers and multiple male and female breeders. Behavioral observations and multilocus DNA fingerprinting have indicated that the social and genetic mating systems of these two species are diverse. Extra‐group paternity appears to be common in both species, necessitating the use of single locus genetic methods to efficiently search for fathers. We therefore characterized 19 microsatellite loci for these two species (12 for magpie‐jays and seven for brown jays) to aid in parentage studies.