Weather and fireblight in England

Agriculture in tropical countries produces many of the world's most valuable crops, but productivity is limited by a multiplicity of different diseases, many of which have been inadequately studied. Certain characteristics of tropical climates have a fundamental influence on the incidence and severity of many of these diseases. The main seasonal variations which control crop growth and disease epidemiology depend on differences in moisture availability rather than daylength and temperature differences. Marked dry seasons hinder the survival of many pathogens outside hosts unless they can produce drought-resistant spores. In many tropical areas continuous cropping throughout the year is possible, enabling disease epidemics to continue without interruption over long periods. Much agriculture in the tropics is at fairly high altitudes enabling temperate crops to be grown, but low temperatures may present special disease hazards. Violent storms are a feature of many tropical climates and have been implicated in the spread of many bacterial diseases. Drought is a factor which influences the severity of many root diseases. The various effects which moisture, as rain or dew, temperature and cropping cycle can have are illustrated by discussion of sigatoka disease of bananas (Mycosphaerella musicola Leach), South American leaf blight of rubber (Microcyclus ulei (R. Henn.) Arx) and coffee berry disease (Colletotrichum coffeanum Noack).     

Regional and local (road verge) effects on size and fecundity in Banksia menziesii

Abstract Banksia menziesii is a tree at the mesic end (Swan Coastal Plain) of its range and a shrub at the xeric end (Eneabba Plain). Plants at the xeric end produced, on average, as many cones, set 2.3 times as many seeds and stored 8.8 times as many viable seeds in the crown, as those at the mesic end. Plants on road verges had, on average, 2.5 times larger crowns than those at least 50 m further from the road. Road edge plants produced, on average, 2.5 times as many cones, set 3.1 times as many seeds and stored 3.7 times as many viable seeds as non-edge plants. Greater fecundity at the xeric end, including the road verges, could help offset the greater incidence of adult deaths and the reduced likelihood of seedling recruitment after fire at Eneabba.     

Competition for mates and predominant juvenile male dispersal in mammals

Competition among males for mates may partially explain the predominant dispersal of juvenile male California ground squirrels (Spermophilus beecheyi). I tested the generality of this hypothesis by comparing dispersal patterns in many species of mammals. In most polygynous and promiscuous species of mammals, juvenile males are the predominant dispersers. In most monogamous species of mammals, juvenile males and juvenile females are predominant dispersers with little distinction as to sex. While many factors may influence dispersal, achieving outcrossing and advantages in competition for mates are most likely to explain predominant dispersal by juvenile males in many mammal species.     

Temperature and embryonic development in polar marine invertebrates

The life-history tactics of many Antarctic marine invertebrates suggest that the commonly observed slow rates of growth are adaptations to the pattern of food availability, and not due to low temperature per se. This implies that marine invertebrates have been able, over the course of evolutionary time, to compensate their rates of embryonic development for the effect of temperature. Data from north Atlantic copepods indicate that this is so. It is therefore suggested that the slow rates of embryonic development in many Antarctic marine invertebrates are the result of large egg size, and not the low temperature. Large, slowly developing eggs are part of a suite of tactics, often called K-strategies, which characterise many marine invertebrates in Antarctica.     

Examination of relaxin and its receptors expression in pig gametes and embryos

Background  

Relaxin is a small peptide also known as pregnancy hormone in many mammals. It is synthesized by both male and female tissues, and its secretions are found in various body fluids such as plasma serum, ovarian follicular fluid, utero-oviduct secretions, and seminal plasma of many mammals, including pigs. However, the presence and effects of relaxin in porcine gametes and embryos are still not well-known. The purpose of this study was to assess the presence of relaxin and its receptors RXFP1 and RXFP2 in pig gametes and embryos.     

Role of Endosomes and Lysosomes in Human Disease

In addition to their roles in normal cell physiology, endocytic processes play a key role in many diseases. In this review, three diseases are discussed as examples of the role of endocytic processes in disease. The uptake of cholesterol via LDL is central to our understanding of atherosclerosis, and the study of this disease led to many of the key breakthroughs in understanding receptor-mediated endocytosis. Alzheimer’s disease is a growing burden as the population ages. Endosomes and lysosomes play important but only partially understood roles in both the formation and the degradation of the amyloid fibrils that are associated with Alzheimer’s disease. Inherited lysosomal storage diseases are individually rare, but collectively they affect many individuals. Recent advances are leading to improved enzyme replacement therapy and are also leading to small-molecule drugs to treat some of these diseases.Endocytosis plays many vital roles in normal cell physiology, and as described in this article, endocytic processes can also play significant roles in pathology. Nutrient uptake is one of the essential functions of endocytosis. Two of the best-characterized examples of this are the uptake of cholesterol via the low-density lipoprotein (LDL) receptor (Goldstein and Brown 2009) and the uptake of iron via transferrin and the transferrin receptor (Aisen et al. 2001). Another important role for endocytosis is the regulation of cell-surface expression of membrane proteins, especially receptors and transporters. The balance between recycling or trafficking to storage organelles or to late endosomes and lysosomes (LE/Ly) is often a determining factor in regulating surface expression levels of membrane proteins. Thus, the membrane sorting that occurs in endosomes is important for regulating cell physiology. The pH levels in endosomes play an important role in many functions of endocytosis, including release of iron from transferrin, release of LDL and other ligands from their receptors, and activation of lysosomal hydrolases. As discussed herein, many of these same processes can also play a role in human diseases. A few specific diseases—atherosclerosis, Alzheimer’s disease, and lysosomal storage diseases—are used to illustrate this.     

Involvement of autophagy and mitochondrial dynamics in determining the fate and effects of irreparable mitochondrial DNA damage

Mitochondrial DNA (mtDNA) is different in many ways from nuclear DNA. A key difference is that certain types of DNA damage are not repaired in the mitochondrial genome. What, then, is the fate of such damage? What are the effects? Both questions are important from a health perspective because irreparable mtDNA damage is caused by many common environmental stressors including ultraviolet C radiation (UVC). We found that UVC-induced mtDNA damage is removed slowly in the nematode Caenorhabditis elegans via a mechanism dependent on mitochondrial fusion, fission, and autophagy. However, knockdown or knockout of genes involved in these processes—many of which have homologs involved in human mitochondrial diseases—had very different effects on the organismal response to UVC. Reduced mitochondrial fission and autophagy caused no or small effects, while reduced mitochondrial fusion had dramatic effects.     

Micro-CT in small animal and specimen imaging

Laboratory systems for microscopic computed tomography (micro-CT) have recently evolved from specialized prototype tools to become essential components of many research laboratories. The availability of commercial systems with almost microscopic resolution and the capability to image live animals has opened up entirely new applications for micro-CT in laboratory investigation. This review describes the technical aspects of micro-CT and highlights some current research applications. Micro-CT has the potential to replace serial histology as the reference standard in many in vitro studies, and provides a practical approach to obtain quantitative information during some longitudinal investigations in vivo.     

Hypermutation and stress adaptation in bacteria

Hypermutability is a phenotype characterized by a moderate to high elevation of spontaneous mutation rates and could result from DNA replication errors, defects in error correction mechanisms and many other causes. The elevated mutation rates are helpful to organisms to adapt to sudden and unforeseen threats to survival. At the same time hypermutability also leads to the generation of many deleterious mutations which offset its adaptive value and therefore disadvantageous. Nevertheless, it is very common in nature, especially among clinical isolates of pathogens. Hypermutability is inherited by indirect (second order) selection along with the beneficial mutations generated. At large population sizes and high mutation rates many cells in the population could concurrently acquire beneficial mutations of varying adaptive (fitness) values. These lineages compete with the ancestral cells and also among themselves for fixation. The one with the ‘fittest’ mutation gets fixed ultimately while the others are lost. This has been called ‘clonal interference’ which puts a speed limit on adaptation. The original clonal interference hypothesis has been modified recently. Nonheritable (transient) hypermtability conferring significant adaptive benefits also occur during stress response although its molecular basis remains controversial. The adaptive benefits of heritable hypermutability are discussed with emphasis on host–pathogen interactions.     

Atypical Development in Plant and Soil Nematodes

Observations of atypical developmental and anatomical characteristics have been recorded for many taxa of soil nematodes. They include the unusual occurrence of extra feeding structures, aberrant configuration of features of both male and female reproductive systems, and the occurrence of intersexes assumed to be functionally female, functionally male, or non-functional. In many cases, hypotheses have been advanced regarding the genetic or developmental mechanisms and environmental stimuli that control, regulate, or facilitate abnormalities, but many are quite speculative and lack experimental verification. Further, the fitness costs or advantages, and the heritability of aberrant characters are largely unknown, except where they clearly preclude reproduction, either apomictic or amphimictic. Underlying mechanisms and ecological consequences may be difficult to study in organisms that are not readily cultured under axenic or sterile laboratory conditions, however information on developmental processes in Caenorhabditis elegans represents an important resource in which to seek homologies.     

Endemism, speciation and adaptive radiation in great lakes

Synopsis Evolution in great lakes has often been both quantitative (many endemic species of distantly related taxa often being present) and qualitative (outstanding levels of adaptive radiation having sometimes been achieved). These situations pose many questions, such as why there are so many endemics and so many superspecialists (and at the same time often many sibling species), as well as presenting problems relating to such matters as convergent evolution in different lakes, the possible role of key innovations, the nature of isolating mechanisms, competition and co-existence in complex communities, the roles of diverse mutualistic associations, and many others. These rich faunas also provide particularly favourable opportunities for studying patterns of speciation, while attempts to elucidate phylogenies in groups such as African cichlid fishes, that have radiated in several lakes, can be pursued on both a broad scale and at the intralacustrine level using both recently developed techniques and time-honoured methods. Rates of evolution, which differ widely between ecologically equivalent taxa in different lakes, have sometimes been extremely rapid, as attested by both molecular data and evidence from field studies. Notwithstanding their evolutionary exuberance, these rich faunas are fragile as demonstrated dramatically by the appalling tragedy that has befallen the haplochromine cichlid flock of Lake Victoria.Paper from the Canadian Society of Zoologists symposium Great Lakes of the World, organized by David L.G. Noakes.     

Fluctuations in resource availability and insect populations

Summary Data are presented which show that fluctuations in the numbers of many insects are determined primarily by fluctuations in the carrying capacity of their habitats. Few studies exist, however, in which the resources available to insect populations have been quantified; due possibly to a too ready acceptance by many biologists of the concept of population equilibria and a concomitant dismissal of the likelihood of resource limitation.     

Modulation and polytypic signaling in GABAergic transmission

Conclusion Using modern techniques, we now find ourselves closer to understanding more clearly the complexity of GABA_A receptor function. Heterogeneity of the GABA_A receptor family has been shown to exist while its significance in the regulation of cell function continues to be evaluated. In closing, it must be said many contributions which brought us to our current understanding of the GABA_A receptor are attributed to the combined efforts of Dr. Erminio Costa and his laboratories. Through many years of dedicated work and perseverance, he and his co-workers have helped to move the neuroscience community rapidly forward. His efforts continue to influence and inspire creative scientific thinking and research development in neuroscience.Special issue dedicated to Dr. Erminio Costa     

Tagged Mutagenesis and Gene-trap in the Moss, Physcomitrella patens by Shuttle Mutagenesis

The moss, Physcomitrella patens has been used as a useful materialin many fields, because of its simple body plan, ease of genetargeting, and other reasons. Although many mutants have beenreported, no method to isolate the corresponding genes was reported.We developed a gene tagging and gene-trap system in P. patensby using the shuttle mutagenesis technique, which has been usedin the budding yeast. In 5264 tagged lines, 203 mutants withaltered developmental or morphological phenotypes were obtained.In 129 of 4757 gene-trap lines, ß-glucuronidase (GUS)activity was detected in some tissue. Although multiple copiesof a tag were detected in many tagged lines by Southern analyses,most copies are likely integrated at the same locus accordingto PCR analyses.     

Isozyme and RAPD markers in relation to in vitro morphogenesis and in vivo development ofVigna radiata (L.) Wilczek

Vigna radiata (L.) Wilczek, popularly known as “mung bean,” is an important protein supplement in vegetarian diets in many countries of Asia. It has a short life cycle (55–70 days) and fits well into many cropping systems, including rice and sugarcane, under rain-fed and irrigated conditions. The present review deals with the data available on plant regeneration of this species. Both shoot-tip multiplication and somatic embryogenesis have been compared on the basis of retrospective as well as recent reports. Molecular markers, especially random amplified polymorphic DNA (RAPD), have been used to compare results obtained from in vitro and in vivo studies on various species ofVigna. Isozyme markers such as esterase and superoxide dismutase, which are expressed during in vitro regeneration and in vivo development ofVigna species, are also included in this article.     

Psychological Aspects of Cystic Fibrosis in Children and Adolescents

Medical care of children with cystic fibrosis has been so greatly improved in recent years that many are now reaching adolescence and early adulthood. Traversing adolescence is a trying task for any chronically ill child, but even more difficult for the cystic fibrosis patient. Clinicians report that many of these adolescents have problems for which the patients, the family, and the practitioners need help. The key to dealing with the problems is to attempt to approach “normality” of living as closely as possible as early as possible despite the risks inherent.     

Recent Observations on Mesenchymal Tumours in Adults and Children

Recognition of the types and characteristics of mesenchymal tumours is important, since each type has biological features peculiar to itself that govern its growth and behaviour and it is essential to know these if treatment is to be effectual. Because many differentiated cell types are capable of acting as facultative fibroblasts, histological diagnosis is often in error. It has been found that no matter how bizarre a tumour may appear, if explanted in vitro, the cells will betray their true nature. By this means the various mesenchymal tumour types have been classified, many examples collected and followed up and their biological potentialities recorded. In more recent studies these uncommon tumours in children have been studied and many of them found to be less malignant than in adults. New varieties of mesenchymal tumours have been discovered in recent years, such as pseudosarcomatous fasciitis, elastofibroma dorsi, and bizarre variants of smooth muscle tumour.     

Involvement of autophagy and mitochondrial dynamics in determining the fate and effects of irreparable mitochondrial DNA damage

Mitochondrial DNA (mtDNA) is different in many ways from nuclear DNA. A key difference is that certain types of DNA damage are not repaired in the mitochondrial genome. What, then, is the fate of such damage? What are the effects? Both questions are important from a health perspective because irreparable mtDNA damage is caused by many common environmental stressors including ultraviolet C radiation (UVC). We found that UVC-induced mtDNA damage is removed slowly in the nematode Caenorhabditis elegans via a mechanism dependent on mitochondrial fusion, fission, and autophagy. However, knockdown or knockout of genes involved in these processes—many of which have homologs involved in human mitochondrial diseases—had very different effects on the organismal response to UVC. Reduced mitochondrial fission and autophagy caused no or small effects, while reduced mitochondrial fusion had dramatic effects.