The Influence of Prior Water Stress and Abscisic Acid Foliar Spraying on Stomatal Responses to CO2, IAA, ABA, and Calcium in Leaves of Solanum melongena

The influence of a water stress or foliar ABA spraying pretreatmenton stomatal responses to water loss, exogenous ABA, IAA, Ca²⁺,and CO₂ were studied using excised leaves of Solanum melongena.Both pretreatments increased stomatal sensitivity of water loss,in the presence and absence of CO₂, but decreased stomatal sensitivityto exogenous ABA. CO₂ greatly reduced the effect of exogenouslyapplied ABA. IAA decreased leaf diffusion resistance for controland ABA sprayed leaves, but did not influence the LDR of previouslywater-stressed leaves. CA²⁺ did not influence LDR of any leavesof any treatments. Key words: Water stress, stomatal response, pretreatments     

Why fly? The possible benefits for lower mortality

In adult endotherms—birds and mammals—mortality rates are lower in flying than non-flying species. Rates vary with size, but allowing for this they are higher in penguins than flying birds, and in rodents than bats. These observations are most simply explained in terms of predation since flight, allowing movement in three dimensions, increases the chances of escape.
There are various problems in obtaining and comparing data on rates of mortality and this partly explains a wide scattering of points. Nevertheless the main results are statistically significant, mostly at P<0.001. Amongst birds, there are several other significant differences. Mortality rates are lower at lower latitudes, and in aquatic compared to terrestrial species, with cliff-nesters having lower rates than other aquatic birds and co-operative breeders than other terrestrial ones. No latitudinal effect was detected in mammals. The exceptionally low rates of mortality in bats and swifts are attributed to their being particularly hard to catch.     

The Presence of Tyrosinase and Related Proteins in Human Epidermis and Their Relationship to Melanin Type

The present study was carried out to investigate the abundance of tyrosinase and related proteins (TRP-1 and TRP-2) in human epidermis and their relationship to melanin type. Positive immunocytochemical staining was seen for all three proteins in epidermal melanocytes. For each protein the numbers of positively stained melanocytes were similar in all subjects studied irrespective of skin type. Following 5 daily suberythemal doses of UVB the melanocytes were larger, more dendritic, and increased in number. With TRP-1 and TRP-2 the increase in number in response to UVB was unrelated to skin type and, hence, with melanin type but with tyrosinase there was a much greater increase in skin types III and IV than in skin type I and II. The enhanced numbers of tyrosinase-positive melanocytes were accompanied by increased staining intensity, suggesting a greater expression of tyrosinase in the melanocytes from skin types III and IV compared with skin types I and II. This increase in tyrosinase could be related to the greater levels of eumelanin found in skin types III and IV, and this is in keeping with the view that higher levels of tyrosinase are associated with the production of eumelanin than phaeomelanin.     

Treatment of athletes

Treating participants in athletics requires the coordination of coaches, trainers, administrators and physician. Often in cases of proneness to injury, a cause can be found and correction may be obtained by further training or withdrawal of the athlete from the team. Certain types of injury should be always kept in mind in the examination of athletes, particularly football players. Ligamentous tears, myositis ossificans, navicular fracture and brain injury are injuries that may not be precisely diagnosed at the initial examination.     

The role of refuge areas in the phenology of Rhopalosiphum padi in low rainfall cropping areas of South Australia

Extensive surveys of possible aphid habitats in South Australia indicated that irrigated perennial grass pastures in the Mount Lofty Ranges and Lower Murray Valley were summer refuges for Rhopalosiphum padi (L.) (Hemiptera: Aphididae). Large numbers of aphids build up in these pastures each year during autumn (April and May) with numbers peaking in May. The size of the May peak was related to the number of aphids surviving the summer. The proportions of alates were highest in May and August/September. Both peaks coincided with a photoperiod of between 11.2 and 11.5 h, and partial correlations suggested that aphid density, photoperiod and temperature were all significant determinants of alate production.     

Protein Synthesis Related to Cold Temperature Stress in the Desiccation-Tolerant Moss Tortula ruralis

Incubation of hydrated Tortula ruralis (Hedw.) Gaertn., Meyer. Scherb. at temperatures down to 2°C resulted in an accumulation of polyribosomes and a decrease in single ribosomes. No changes in the levels of ribosomal subunits were detected. On rehydration of slowly dried moss, which contains no polyribosomes, these were reormed at 2, 8 and 20°C. Rapid incorporation of labelled leucine into protein was observed on reintroduction of the desiccated plant o water at 20°C and there was significant, but much reduced, ncorporation at 2°C. Previously undesiccated moss was also able o take up radioactive leucine and to synthesize protein at 2 and -2.5°C. Changes in the rate of protein synthesis at low temperature were not detected in cold hardened (winter collected or incubated at 2°C) T. ruralis. The moss appears to be adapted to survive freezing wear round and even summer-collected moss can conduct protein synthesis at low temperatures: seasonal cold hardiness changes do lot appear to take place.     

Population genomics of wild and laboratory zebrafish (Danio rerio)

Understanding a wider range of genotype–phenotype associations can be achieved through ecological and evolutionary studies of traditional laboratory models. Here, we conducted the first large‐scale geographic analysis of genetic variation within and among wild zebrafish (Danio rerio) populations occurring in Nepal, India, and Bangladesh, and we genetically compared wild populations to several commonly used lab strains. We examined genetic variation at 1832 polymorphic EST‐based single nucleotide polymorphisms (SNPs) and the cytb mitochondrial gene in 13 wild populations and three lab strains. Natural populations were subdivided into three major mitochondrial DNA clades with an average among‐clade sequence divergence of 5.8%. SNPs revealed five major evolutionarily and genetically distinct groups with an overall F_ST of 0.170 (95% CI 0.105–0.254). These genetic groups corresponded to discrete geographic regions and appear to reflect isolation in refugia during past climate cycles. We detected 71 significantly divergent outlier loci (3.4%) and nine loci (0.5%) with significantly low F_ST values. Valleys of reduced heterozygosity, consistent with selective sweeps, surrounded six of the 71 outliers (8.5%). The lab strains formed two additional groups that were genetically distinct from all wild populations. An additional subset of outlier loci was consistent with domestication selection within lab strains. Substantial genetic variation that exists in zebrafish as a whole is missing from lab strains that we analysed. A combination of laboratory and field studies that incorporates genetic variation from divergent wild populations along with the wealth of molecular information available for this model organism provides an opportunity to advance our understanding of genetic influences on phenotypic variation for a vertebrate species.     

Leaf-surface Wax in Poa colensoi

Leaf-surface wax present on greenhouse-grown Poa colensoi plantsfrom seed samples representative of thirteen field populationswas measured quantitatively and related to field climates. Theamount of wax inherently formed on leaves of P. colensoi plantswas found to be highly and negatively correlated with aridityof their field environments and slightly positively correlatedwith field temperatures. Electron-micrographs were obtained from the leaf-surfaces ofplants originating in semi-arid and mesophytic habitats. Thesemicrographs indicated the relative amounts of wax present onglaucous and green leaves in the species. The nature of waxdeposits on P. colensoi leaves has been described in relationto those found on other plant species.     

Individually mark–mass release–resight study elucidates effects of patch characteristics and distance on host patch location by an insect herbivore

1. How organisms locate their hosts is of fundamental importance in a variety of basic and applied ecological fields, including population dynamics, invasive species management and biological control. However, tracking movement of small organisms, such as insects, poses significant logistical challenges. 2. Mass‐release and individual–mark–recapture techniques were combined in an individually mark–mass release–resight (IMMRR) approach to track the movement of over 2000 adult insects in an economically important plant–herbivore system. Despite its widespread use for the biological control of the invasive thistle Carduus nutans, the host‐finding behaviour of the thistle head weevil Rhinocyllus conicus has not previously been studied. Insects were released at different distances from a mosaic of artificially created host patches with different areas and number of plants to assess the ecological determinants of patch finding. 3. The study was able to characterize the within‐season dispersal abilities and between‐patch movement patterns of R. conicus. Weevils found host plant patches over 900 m away. Large patches, with tall plants, situated close to the nearest release point had the highest first R. conicus resights. Patch area and plant density had no effect on the number of weevils resighted per plant; however, R. conicus individuals were more likely to disperse out of small patches and into large patches. 4. By understanding how R. conicus locates host patches of C. nutans, management activities for the control of this invasive thistle can be better informed. A deeper mechanistic understanding of host location will also improve prediction of coupled plant–herbivore spatial dynamics in general.