The prickly pear (Opuntia ficus-indica [Cactaceae]) in South Africa: Utilization of the naturalized weed,and of the cultivated plants

In spite of successful biological control efforts, vast areas of South Africa remain infested with the spiny prickly pear weed, Opuntia ficus-indica. These remnant populations, which vary from sparse to dense and which are more or less stable, are confined mainly to the eastern Cape. They provide a popular fruit and a limited source of income for certain sectors of the population in these areas. In terms of existing legislation, there are, however, restrictions on the large-scale utilization of these fruit. A novel method for mass-rearing the cochineal insect, Dactylopius coccus, for the commercial production of a red dye (carminic acid) has been developed. The cultivated spineless prickly pear has recently been enjoying renewed attention from researchers and growers alike. Whereas it has traditionally been cultivated mainly as a droughtresistant fodder crop, and is still popular as such, it is now increasingly recognised as a fruit, in its own right, with considerable promise as a commercial crop for local and export markets. There is also a need to encourage the use of very young cladodes (nopalitos) as a highly nutritious vegetable for human consumption in South Africa.     

Alterations of Choroidal Blood Flow Regulation in Young Healthy Subjects with Complement Factor H Polymorphism

A common polymorphism in the complement factor H gene (rs1061170, Y402H) is associated with a high risk of age-related macular degeneration (AMD). In the present study we hypothesized that healthy young subjects homozygous for the high-risk haplotype (CC) show abnormal choroidal blood flow (ChBF) regulation decades before potentially developing the disease. A total of 100 healthy young subjects were included in the present study, of which 4 subjects were excluded due to problems with genotyping or blood flow measurements. ChBF was measured continuously using laser Doppler flowmetry while the subjects performed isometric exercise (squatting) for 6 minutes. The increase in ChBF was less pronounced than the response in ocular perfusion pressure (OPP), indicating for some degree of choroidal blood flow regulation. Eighteen subjects were homozygous for C, 47 subjects were homozygous for T and 31 subjects were heterozygous (CT). The increase in OPP during isometric exercise was not different between groups. By contrast the increase in ChBF was more pronounced in subjects homozygous for the high risk C allele (p = 0.041). This was also evident from the pressure/flow relationship, where the increase in ChBF in homozygous C carriers started at lower OPPs as compared to the other groups. Our data indicate that the regulation of ChBF is abnormal in rs1061170 CC carriers. So far this polymorphism has been linked to age related macular degeneration (AMD) mainly via inflammatory pathways associated with the complement system dysfunction. Our results indicate that it could also be related to vascular factors that have been implicated in AMD pathogenesis.     

Water flow influences oxygen transport and photosynthetic efficiency in corals

Recent studies indicate that the incidence and persistence of damage from coral reef bleaching are often highest in areas of restricted water motion, and that resistance to and recovery from bleaching is increased by enhanced water motion. We examined the hypothesis that water motion increases the efflux of oxygen from coral tissue thereby reducing oxidative stress on the photosynthetic apparatus of endosymbiotic zooxanthellae. We experimentally exposed colonies of Montastrea annularis and Agaricia agaricites to manipulations of water flow, light intensity, and oxygen concentration in the field using a novel mini-flume. We measured photosynthetic efficiency using a pulse amplitude modulated fluorometer to test the short-term response of corals to our manipulations. Under normal oxygen concentrations, A. agaricites showed a significant 8% increase in photosynthetic efficiency from 0.238 (± 0.032) in still water to 0.256 (± 0.037) in 15 cm s⁻¹ flow, while M. annularis exhibited no detectable change. Under high-ambient oxygen concentrations, the observed effect of flow on A. agaricites was reversed: photosynthetic efficiencies showed a significant 11% decrease from 0.236 (± 0.056) in still water to 0.211 (± 0.048) in 15 cm s⁻¹ flow. These results support the hypothesis that water motion helps to remove oxygen from coral tissues during periods of maximal photosynthesis. Flow mitigation of oxidative stress may at least partially explain the increased incidence and severity of coral bleaching in low flow areas and observations of enhanced recovery in high-flow areas.     

Thermal tolerance and climate warming sensitivity in tropical snails

Tropical ectotherms are predicted to be especially vulnerable to climate change because their thermal tolerance limits generally lie close to current maximum air temperatures. This prediction derives primarily from studies on insects and lizards and remains untested for other taxa with contrasting ecologies. We studied the HCT (heat coma temperatures) and ULT (upper lethal temperatures) of 40 species of tropical eulittoral snails (Littorinidae and Neritidae) inhabiting exposed rocky shores and shaded mangrove forests in Oceania, Africa, Asia and North America. We also estimated extremes in animal body temperature at each site using a simple heat budget model and historical (20 years) air temperature and solar radiation data. Phylogenetic analyses suggest that HCT and ULT exhibit limited adaptive variation across habitats (mangroves vs. rocky shores) or geographic locations despite their contrasting thermal regimes. Instead, the elevated heat tolerance of these species (HCT = 44.5 ± 1.8°C and ULT = 52.1 ± 2.2°C) seems to reflect the extreme temperature variability of intertidal systems. Sensitivity to climate warming, which was quantified as the difference between HCT or ULT and maximum body temperature, differed greatly between snails from sunny (rocky shore; Thermal Safety Margin, TSM = −14.8 ± 3.3°C and −6.2 ± 4.4°C for HCT and ULT, respectively) and shaded (mangrove) habitats (TSM = 5.1 ± 3.6°C and 12.5 ± 3.6°C). Negative TSMs in rocky shore animals suggest that mortality is likely ameliorated during extreme climatic events by behavioral thermoregulation. Given the low variability in heat tolerance across species, habitat and geographic location account for most of the variation in TSM and may adequately predict the vulnerability to climate change. These findings caution against generalizations on the impact of global warming across ectothermic taxa and highlight how the consideration of nonmodel animals, ecological transitions, and behavioral responses may alter predictions of studies that ignore these biological details.     

Simpler is better: fewer non‐target insects trapped with a four‐component chemical lure vs. a chemically more complex food‐type bait for Drosophila suzukii

Baits – fermented food products – are generally attractive to many types of insects, which makes it difficult to sort through non‐target insects to monitor a pest species of interest. We test the hypothesis that a chemically simpler and more defined attractant developed for a target insect is more specific and attracts fewer non‐target insects than a chemically more complex food‐type bait. A four‐component chemical lure isolated from a food bait and optimized for the spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), was compared to the original wine/vinegar bait to assess the relative responses of non‐target insects. In several field experiments in Washington State, USA, it was shown that numbers of pest muscid flies, cutworm and armyworm moths, and pest yellowjackets were reduced in traps baited with the chemical lure compared to the wine/vinegar bait. In other field experiments in the states of Washington, Oregon, and New York, numbers of non‐target drosophilid flies were also reduced in traps baited with the chemical lure relative to wine/vinegar bait. In Washington, numbers of Drosophila melanogaster Meigen and Drosophila obscura Fallen species groups and Drosophila immigrans Sturtevant were reduced in the chemical lure traps, whereas in New York, D. melanogaster and D. obscura species groups, D. immigrans, Drosophila putrida Sturtevant, Drosophila simulans Sturtevant, Drosophila tripunctata Loew, and Chymomyza spp. numbers were reduced. In Oregon, this same effect was observed with the D. melanogaster species group. Taken together, these results indicate that the four‐component SWD chemical lure will be more selective for SWD compared to fermentation baits, which should reduce time and cost involved in trapping in order to monitor SWD.     

Selective Staining by the Fluorochrome 5,5'-Diphenyl-9-ethyl-oxacarbocyanine. II. Application to Paraffin Embedded Nervous Tissue

We present a simple and rapid method to label specific structures of neural tissue in paraffin sections. After incubation of deparaffinized sections in the cyanine dye 5,5'-diphenyl-9-ethyl-oxacarbocyanine (DEOC), three different washing and mounting procedures were performed. Incubation in DEOC followed by washes in ethanol and water and mounting in glycerol-gelatin resulted in selective labeling of myelin in the central and peripheral nervous systems. Weak labeling of myelin and axons and staining of nuclei of neurons was seen after incubation in DEOC followed by washes in ethanol and xylene, and mounting in Eukitt. Nuclear proteins, the endoplasmic reticulum and the Golgi apparatus were stained strongly and exclusively after incubation in DEOC, washes in water, ethanol and xylene, and mounting in Eukitt. Thus the absorption pattern of DEOC is changed significantly by solvents applied after the fluorochrome. In any case, fluorescence did not fade even after repeated and intense fluorescence microscopy over a period of 6 months.