Subterranean glacial spillways: an example from the karst of South Wales, UK

Many karst areas in the UK have been glaciated one or more times during the last 0.5 Ma, yet there are few documented examples of caves in these regions being affected by glacial processes other than erosion. The karst of South Wales is one area where sub or pro-glacial modification of pre-existing caves is thought to occur. Evidence from the Ogof Draenen cave system suggests that caves can sometimes act as subterranean glacial ‘underspill’ channels for melt-water. This cave, one of the longest in Britain with a surveyed length of over 70 km, underlies the interfluve between two glaciated valleys. Sediment fills and speleo-morphological observations indicate that melt-water from a high level glacier in the Afon Lwyd valley (>340m asl) filled part of the cave and over-spilled into the neighbouring Usk valley, temporarily reversing non-glacial groundwater flow directions in the cave. It is suggested that this may have occurred during a Middle Pleistocene glaciation

A structural investigation of the sulphated polysaccharide pachymenia carnos (J. Ag.) J. Ag.

The highly sulphated, methylated polysaccharide isolated from Pachymenia Carnosa, a red seaweed, was shown to contain D- galactose, 2-o (underscore) methyl-D- galactose, 6-o (underscore) -methyl- D- galactose and 4-o (underscore)-methylgalactose. The polysaccharide was desulphated with methanolic hydrogen chloride. Methylation of the desulphated polysaccharide revealed that it was composed entirely of (1→73) and (1→4) links in approximately equal amounts. Treatment of the polysaccharide with alkali showed that the majority of the ester sulphate groups were alkali-stable. Partial hydrolysis and acetolysis studies indicated that the polysaccharide was extremely complex, and contained alternate (1→3) and β (1→4) glycosidic linkages. There is evidence for the presence of D-galactose-6-sulphate

An ultrastructural investigation of the surface microbiota present on the leaves and reproductive structures of the resurrection plant Myrothamnus flabellifolia

The leaves, flower and stems of the southern African angiosperm resurrection plant Myrothamnus flabellifolia were investigated at the ultrastructural level to determine the source of previously reported fungal contamination. Fungal mycelia and hyphae of the genera Aspergillus and Penicillium were found localized to the hydathodes of the leaves and stigmatic surfaces of the female flowers in both desiccated and hydrated specimens. A waxy bacterium of the genus Bacillus was found to colonise the waxy epidermal surfaces of the leaves and flowers which was also where fungal cells were found to be absent. It is suggested that the wax like deposits within the leaves and stems as well as over the epidermal surface prevent the growth of the fungal organisms. These fungi opportunistically invade moist surfaces, such as the floral stigmas, during periods of moisture availability and may thus negatively impact plant development

Insights into the cellular mechanisms of desiccation tolerance among angiosperm resurrection plant species

ABSTRACT Water is a major limiting factor in growth and reproduction in plants. The ability of tissues to survive desiccation is commonly found in seeds or pollen but rarely present in vegetative tissues. Resurrection plants are remarkable as they can tolerate almost complete water loss from their vegetative tissues such as leaves and roots. Metabolism is shut down as they dehydrate and the plants become apparently lifeless. Upon rehydration these plants recover full metabolic competence and 'resurrect'. In order to cope with desiccation, resurrection plants have to overcome a number of stresses as water is lost from the cells, among them oxidative stress, destabilization or loss of membrane integrity and mechanical stress. This review will mainly focus on the effect of dehydration in angiosperm resurrection plants and some of the strategies developed by these plants to tolerate desiccation. Resurrection plants are important experimental models and understanding the physiological and molecular aspects of their desiccation tolerance is of great interest for developing drought-tolerant crop species adapted to semi-arid areas

Wellbeing and healthcare access for sexuality and gender minority secondary school students with long-term health conditions

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Reconstruction of MIS 5 climate in the central Levant using a stalagmite from Kanaan Cave, Lebanon

Lying at the transition between the temperate Mediterranean domain and subtropical deserts, the Levant is a key area to study the palaeoclimatic response over glacial–interglacial cycles. This paper presents a precisely dated last interglacial (MIS 5) stalagmite (129–84 ka) from the Kanaan Cave, Lebanon. Variations in growth rate and isotopic records indicate a warm humid phase at the onset of the last interglacial at ~ 129 ka that lasted until ~ 125 ka. A gradual shift in speleothem isotopic composition (125–122 ka) is driven mainly by the δ18O source effect of the eastern Mediterranean surface waters during sapropel 5 (S5). The onset of glacial inception began after ~ 122 ka, interrupted by a short wet pulse during the sapropel 4 (S4) event. Low growth rates and enriched oxygen and carbon values until ~ 84 ka indicate a transition to drier conditions during Northern Hemisphere glaciation

Screening Different Zambian Market Classes of Common Beans (Phaseolus vulgaris) for Antioxidant Properties and Total Phenolic Profiles

Abstract Nutraceutical foods are thought to play an important role in the prevention and management of cardiovascular diseases, diabetes, obesity and some cancers. This study was undertaken to screen the commonly grown Zambian market classes of common beans for nutraceutical value based on the antioxidant activities (DPPH and FRAP) and total polyphenolic profiles. Phenolic phytochemical profiles were determined using Folin Ciocalteu assay and aluminium chloride colorimetric method. The total polyphenol content ranged from 37.3 to 123.7 mg GAE / 100 g DW. Red beans consistently displayed the highest total polyphenol contents in both the methanolic and aqueous extracts, followed by grey mottled, brown and white. Tannin concentration ranged from 10.2 to 55.4 mg GAE / 100 g DW for the aqueous and from 3.1 to 53 mg GAE / 100 g DW for the 70% methanol extract. Flavonoid concentration ranged from 42.1 to 62.6 mg quercetin equivalents / 100 g DW (aqueous extraction) and 95.2 to 123.5 mg quercetin equivalents / 100 g DW (70% methanol extraction). The various classes of common beans displayed varying antioxidant activities. The bean extracts exhibited DPPH free radical scavenging activities with pseudo firstorder rate constants (K) ranging between 0.006 min -1 and 0.053 min -1 and FRAP derived antioxidant power between 1.69 and 6.88 Fe 2+ / 100 g DW. The red market class displayed the highest antioxidant activity in the aqueous extract, but showed little difference with the grey mottled beans in the methanolic extract. Ranking the market classes based on the free radical scavenging capacities and the FRAP-derived total antioxidant power, the following order was observed: red beans > grey mottled beans > brown beans > white beans. On a comparative basis, white beans displayed far lower antioxidant activities compared to the others. Keywords: antioxidant, polyphenols, nutraceuticals, common beans Cite This Article

Synapse-specific expression of calcium-permeable AMPA receptors in neocortical layer 5

In the hippocampus, calcium‐permeable AMPA receptors have been found in a restricted subset of neuronal types that inhibit other neurons, although their localization in the neocortex is less well understood. In the present study, we looked for calcium‐permeable AMPA receptors in two distinct populations of neocortical inhibitory neurons: basket cells and Martinotti cells. We found them in the former but not in the latter. Furthermore, in basket cells, these receptors were associated with particularly fast responses. Computer modelling predicted (and experiments verified) that fast calcium‐permeable AMPA receptors enable basket cells to respond rapidly, such that they promptly inhibit neighbouring cells and shut down activity. The results obtained in the present study help our understanding of pathologies such as stroke and epilepsy that have been associated with disordered regulation of calcium‐permeable AMPA receptors

Synapse Type-Dependent Expression of Calcium-Permeable AMPA Receptors

Calcium-permeable (CP) AMPA-type glutamate receptors (AMPARs) are known to mediate synaptic plasticity in several different interneuron (IN) types. Recent evidence suggests that CP-AMPARs are synapse-specifically expressed at excitatory connections onto a subset of IN types in hippocampus and neocortex. For example, CP-AMPARs are found at connections from pyramidal cells (PCs) to basket cells (BCs), but not to Martinotti cells (MCs). This synapse type-specific expression of CP-AMPARs suggests that synaptic dynamics as well as learning rules are differentially implemented in local circuits and has important implications not just in health but also in disease states such as epilepsy