Pigmentary Rhythms as Indicators of Neurosecretion

The state of contraction of crustacean chromatophores is knownto be dependent on a variety of hormones secreted by variousparts of the nervous system. For the fiddler crab the stateof the chromatophores varies with the time of day and is littleaffected by changes in light intensity or background. An additionalfactor influencing chromatophores is a lunar-tidal rhythm. Theeffects of naturally-changing photoperiods and of a constantartificial photoperiod on the condition of the chromatophoresof Uca pugnax are described. The lunar-tidal rhythm is seento affect the chromatophores at hours transitional between theday and night phase for at least 2 months after the animalsare removed from tidal conditions. The time of entrance intothe night phase of the diurnal rhythm varies widely as a functionof phase of the moon when the animals are exposed to long photoperiods.Short photoperiods restrict the range of this variation butappear to have little effect on the minimum duration of theday phase in any 15-day period. Consideration of both diurnaland tidal rhythms may permit selection of times of maximum differencesin chromatophores which might also reflect maximum differencesin neurosecretory activity.     

Surface soil chemical and physical patterns in a brigalow–Dawson gum forest,central Queensland

Brigalow (Acacia harpophylla)–Dawson gum (Eucalyptus cambageana) open forests are predominantly supported by solodic soils in central Queensland. This report describes relations between some physical, chemical and morphological properties of surface soils (0–0.10 m) within a virgin brigalow–Dawson gum forest. Soil property gradients were found to radiate horizontally from tree-dominated to non-vegetated areas, indicative of a vegetation-induction process. These reflect the importance of litterfall organic matter in determining soil fertility and soil physical conditions at this site. The decomposition of litterfall is probably responsible for significant increases in soil organic carbon (C), total nitrogen (N) and total sulphur (S) concentrations with increasing vegetation canopy cover. The composition of soil organic matter appears constant across the study area, as similar soil C:N:S ratios were recorded across all vegetation canopy classes. Soil salinity, total phosphorus, mineral nitrogen, cation exchange capacity, exchangeable calcium and exchangeable potassium levels also increased with increasing vegetation canopy cover. Surface soil physical properties were also related to vegetation canopy cover. Bulk density and the < 20 μm dispersion ratio decreased while soil micro-relief and A hor?izon depth increased with increasing vegetation canopy cover. Organic C, through inverse relations with bulk density and the < 20 μm dispersion ratio, appears to enhance soil porosity and aggregate stability, indicating the role of organic matter in the stabilization of larger virgin soil aggregates. The close association between virgin forest and surface soil fertility is seen to have implications for changes in land-use, with a decline in nutrient availability, soil aggregate stability and productivity following forest clearing.     

Photosynthetic CO2 fixation in spinach chloroplasts inhibited by pine chloroplasts or extracts of pine chloroplasts

Chloroplasts isolated from pine needles were found to be inactive with respect to CO₂ fixation. Since it was suspected that pine needles may contain substances inhibitory to photosynthesis, studies were carried out using photosynthetically active isolated spinach chloroplasts and chloroplasts isolated from pine needles. When isolated pine chloroplasts were suspended in buffer and were added to isolated spinach chloroplasts they inhibited photosynthetic CO₂ fixation. When the pine chloroplasts were separated from the medium by centrifugation, the separated pine chloroplasts severely inhibited CO₂ fixation by isolated spinach chloroplasts, but the supernatant solution from the pine chloroplasts was not inhibitory. As little as 5% pine chloroplasts (based on chlorophyll content) produced 50% inhibition of CO₂ fixation by the spinach chloroplasts. Studies of fixation of ¹⁴C-labelled CO₂ by spinach chloroplasts were carried out in which after 5 min photosynthesis the pine chloroplasts were added. It was found that the subsequent inhibition of spinach CO₂ fixation was neither due to any effect on the rate of export of photosynthetic metabolites from the chloroplasts to the medium, nor to a direct effect on the RUBP carboxylase reaction. The principal effect was found to be an inhibition of the conversion of fructose-1,6-bisphosphate and sedoheptulose-1,7-bisphosphate to the respective monophosphates and inorganic phosphate. From this finding it was concluded that a principal effect of the inhibition by pine chloroplasts is probably an inhibition either directly or indirectly of the bisphosphatase enzymes in the spinach chloroplasts. Based on its distribution between organic and aqueous acidic or neutral solutions, the inhibitory factor of the pine chloroplasts must be lipophilic. Most of the factor could be transferred to an aqueous phase in a strongly alkaline solution. Following subsequent acidification of the aqueous phase the activity could be completely transferred back into the organic phase. This procedure allowed for separation of the inhibitory factor from most of the pigments and other lipophilic substances present in the pine chloroplasts and yielded a preparation which could be subsequently fractionated by thin layer chromatography. UV absorption was found in two fast moving spots and at the origin. The fastest running spot from the thin layer chromatography plate was found to be the one containing most of the inhibitory activity.     

SOME LESSER KNOWN FEATURES OF THE ANCIENT CEPHALOPOD ORDER ELLESMEROCERIDA (NAUTILOIDEA, CEPHALOPODA)

Abstract:  Three specimens of the small breviconic ellesmeroceratid Paradakeoceras minor Flower, 1964 from the Tremadocian of the New York area preserve the annular elevation and muscle scars in moulds of the body chamber. The annular elevation is positioned at the base of the body chamber and is wider on the convex side of the shell than on the concave side. Multiple paired muscle scars can be seen within this annular elevation. A well-preserved body chamber of the breviconic ellesmeroceratid Levisoceras cf. edwardsi Ulrich, Foerste and Miller is described. Its body chamber shows a strong anterior–posterior asymmetry, which is common within the Ellesmeroceratida. The shape of the body chamber and of the soft body attachment structures has led to a reconstruction of an ellesmeroceratid soft body that is organized like a primitive conchiferan mollusc. Based on this reconstruction, a tryblidian cephalopod ancestor is supported. An evolutionary scenario is reconstructed from an ancestral nautiloid that is stretched along the anterior–posterior axis, and has serially arranged shell muscles and a small mantle cavity, towards a modern cephalopod with a dorsal–ventral body orientation, reduced number of shell muscles and a large mantle cavity.     

Use and commercialization of Podocnemis expansa (Schweiger 1812) (Testudines: Podocnemididae) for medicinal purposes in two communities in North of Brazil

The emergence of alternative medicines for AIDS in Asia and Africa was discussed at a satellite symposium and the parallel session on alternative and traditional treatments of the AIDSImpact meeting, held in Marseille, in July 2007. These medicines are heterogeneous, both in their presentation and in their geographic and cultural origin. The sessions focused on the role of these medications in selected resource poor settings in Africa and Asia now that access to anti-retroviral therapy is increasing. The aims of the sessions were to (1) identify the actors involved in the diffusion of these alternative medicines for HIV/AIDS, (2) explore uses and forms, and the way these medicines are given legitimacy, (3) reflect on underlying processes of globalisation and cultural differentiation, and (4) define priority questions for future research in this area. This article presents the insights generated at the meeting, illustrated with some findings from the case studies (Uganda, Senegal, Benin, Burkina Faso, China and Indonesia) that were presented. These case studies reveal the wide range of actors who are involved in the marketing and supply of alternative medicines. Regulatory mechanisms are weak. The efficacy claims of alternative medicines often reinforce a biomedical paradigm for HIV/AIDS, and fit with a healthy living ideology promoted by AIDS care programs and support groups. The AIDSImpact session concluded that more interdisciplinary research is needed on the experience of people living with HIV/AIDS with these alternative medicines, and on the ways in which these products interact (or not) with anti-retroviral therapy at pharmacological as well as psychosocial levels.     

OUGHT WE TO ENHANCE OUR COGNITIVE CAPACITIES?1

Ought we to improve our cognitive capacities beyond the normal human range? It might be a good idea to level out differences between peoples cognitive capacities; and some people's reaching beyond normal capacities may have some good side‐effects on society at large (but also bad side‐effects, of course). But is there any direct gain to be made from having ones cognitive capacities enhanced? Would this as such make our lives go better? No, I argue; or at least there doesn't seem to be any evidence suggesting that it would. And it doesn't matter whether we consider the question from a narrow hedonistic perspective, from a more refined hedonistic perspective, from a desire‐satisfaction view, or from some reasonable objective list view of what makes a life go well. Only an extremely perfectionist – and implausible – view of what makes our lives go well could support any direct value in cognitive enhancement. Finally, our sense of identity gives us no good reasons to enhance even our capacity to remember. So, cognitive enhancement as such would not improve our lives.     

Behavioural responses of carnivorous marsupials (Planigale maculata) to toxic invasive cane toads (Bufo marinus)

The arrival of a toxic invasive species may impose selection on local predators to avoid consuming it. Feeding responses may be modified via evolutionary changes to behaviour, or via phenotypic plasticity (e.g. learning, taste aversion). The recent arrival of cane toads (Bufo marinus) in the Northern Territory of Australia induced rapid aversion learning in a predatory marsupial (the common planigale, Planigale maculata). Here, we examine the responses of planigales to cane toads in north‐eastern Queensland, where they have been sympatric for over 60 years, to investigate whether planigale responses to cane toads have been modified by long‐term exposure. Responses to toads were broadly similar to those documented for toad‐naïve predators. Most Queensland planigales seized (21 of 22) and partially consumed (11 of 22) the first toad they were offered, but were likely to ignore toads in subsequent trials. However, unlike their toad‐naïve conspecifics from the Northern Territory, the Queensland planigales all survived ingestion of toad tissue without overt ill effects and continued to attack toads in a substantial proportion of subsequent trials. Our data suggest that (i) learning by these small predators is sufficiently rapid and effective that selection on behaviour has been weak; and (ii) physiological tolerance to toad toxins may be higher in planigales after 60 years (approximately 60 generations) of exposure to this toxic prey.     

The influence of the host plant on the population dynamics of Acizzia russellae (Homoptera: Psyllidae)

Abstract. 1. The role of the host plant, Acacia karroo , in the population dynamics of the indigenous non-pest psyllid, Acizzia russellae , was investigated.
2. Population levels of A.russellae in early summer were almost 10 times greater on the regenerative foliage of pruned trees (cut back in spring) than on normal trees. During late summer and winter, populations declined far more slowly on pruned trees, so that very much higher numbers of psyllids were maintained on these trees through to the next spring. This finding, and others, suggest that natural enemies and climate are not major determinants in the population dynamics of this insect under normal conditions in the field.
3. Laboratory measurements of several chemical and physical characteristics of the foliage of pruned and normal trees did not reveal any differences which would account for the observed effects.
4. Measurements of organic nitrogen concentrations in the leaves of normal A. karroo trees in the field showed significant correlations between psyllid numbers and leaf nitrogen, but only during summer in November and January.
5. Psyllid performance in the laboratory (duration of life cycle, egg production, and dry weight of emergent females) was significantly better for psyllids reared on plants containing high amino nitrogen.
6. It is suggested that the availability of quantities of suitably high quality nutrients in the leaves of pruned A. karroo trees explains the "epidemic" population levels achieved by the psyllid on pruned plants. It seems that characteristics of the host plant impose the major limitation on psyllid population growth, which may explain the permanent low endemic population levels of this insect in the field.     

Molecular evidence of the survival of subterranean amphipods (Arthropoda) during Ice Age underneath glaciers in Iceland

Two endemic groundwater arthropod crustacean species, Crangonyx islandicus and Crymostygius thingvallensis, were recently discovered on the mid‐Atlantic volcanic island of Iceland. The extent of morphological differences from closest relatives, endemism, along with the geographic isolation of Iceland and its complete coverage by glaciers 21 000 years ago, suggests that these two species have survived glaciation periods in sub‐glacial refugia. Here we provide strong support for this hypothesis by an analysis of mitochondrial genetic variation within Crangonyx islandicus. Our results show that the species is divided into several distinct monophyletic groups that are found along the volcanic zone in Iceland, which have been separated by 0.5 to around 5 million years. The genetic divergence between groups reflects geographic distances between sampling sites, indicating that divergence occurred after the colonization of Iceland. The genetic patterns, as well as the dependency of genetic variation on distances from the tectonic plate boundary and altitude, points to recent expansion from several refugia within Iceland. This presents the first genetic evidence of multicellular organisms as complex as crustacean amphipods which have survived glaciations beneath an ice sheet. This survival may be explained by geothermal heat linked to volcanic activities, which may have maintained favourable habitats in fissures along the tectonic plate boundary in Iceland during glaciations.