How to discover new antibiotics: harvesting the parvome

There is a dire need for new antibiotics; commercial discovery programs have essentially dried up and there is talk of 'a return to the pre-antibiotic era'. Natural products are an inexhaustible source of bioactive compounds (antibiotics among them), and recent technical advances such as DNA sequencing and bioinformatics offer new approaches to small molecule discovery. Given that nucleotide sequence studies of actinomycetes genomes reveal the presence of 20 or more pathways for the synthesis of bioactive compounds, 'mining' these sequences offers the potential of expanding the repertoire of antibiotics and other drugs. Combined with advanced chemical separation and characterization techniques, the construction of large chemically diverse libraries of bioactive compounds for therapeutic applications is a realistic near-term goal.     

How plants cope with biotic interactions

In their natural environment, plants interact with many different organisms. The nature of these interactions may range from positive, for example interactions with pollinators, to negative, such as interactions with pathogens and herbivores. In this special issue, the contributors provide several examples of how plants manage both positive and negative biotic interactions. This review aims to relate their findings to what we know about the complex natural environments in which plants have evolved. Molecular analyses of plant genomes and expression profiles have shown how intricately plants may regulate responses to single or multiple biotic interactions. Plant responses are fine-tuned by signalling hormone interactions. When multiple organisms interact with a single plant this may result in antagonistic or synergistic effects. The emerging fields of ecogenomics and metabolomics undoubtedly will refine our understanding of the multilayered regulation that plants use to manage relationships with their biotic environment. However, we can only understand why plants have such an intricate regulatory apparatus if we consider the ecological context of plant biotic interactions.     

How plants cope with complete submergence

Flooding is a widespread phenomenon that drastically reduces the growth and survival of terrestrial plants. The dramatic decrease of gas diffusion in water compared with in air is a major problem for terrestrial plants and limits the entry of CO(2) for photosynthesis and of O(2) for respiration. Responses to avoid the adverse effects of submergence are the central theme in this review. These include underwater photosynthesis, aerenchyma formation and enhanced shoot elongation. Aerenchyma facilitates gas diffusion inside plants so that shoot-derived O(2) can diffuse to O(2)-deprived plant parts, such as the roots. The underwater gas-exchange capacity of leaves can be greatly enhanced by a thinner cuticle, reorientation of the chloroplasts towards the epidermis and increased specific leaf area (i.e. thinner leaves). At the same time, plants can outgrow the water through increased shoot elongation, which in some species is preceded by an adjustment of leaf angle to a more vertical position. The molecular regulatory networks involved in these responses, including the putative signals to sense submergence, are discussed and suggestions made on how to unravel the mechanistic basis of the induced expression of various adaptations that alleviate O(2) shortage underwater.     

How mice cope with stressful social situations

Individuals differ greatly in their psychological responses to chronic stress. As a step toward understanding the neural basis for these individual differences, Krishnan et al. (2007) reveal molecular changes in the brain's reward circuits that make some mice resistant to the effects of social defeat.     

How house officers cope with their mistakes.

We examined how house officers coped with serious medical mistakes to gain insight into how medical educators should handle these situations. An anonymous questionnaire was mailed to 254 house officers in internal medicine asking them to describe their most important mistake and their response to it; 45% (N = 114) reported a mistake and completed the questionnaire. House officers experienced considerable emotional distress in response to their mistakes and used a variety of strategies to cope. In multivariate analysis, those who coped by accepting responsibility were more likely to make constructive changes in practice, but to experience more emotional distress. House officers who coped by escape-avoidance were more likely to report defensive changes in practice. For house officers who have made a mistake, we suggest that medical educators provide specific advice about preventing a recurrence of the mistake, provide emotional support, and help them understand that distress is an expected concomitant of learning from the experience.     

Medical schools seeking new ways to cope with funding cutbacks

Cuts in government funding mean that Canada''s medical schools have to seek new ways to raise funds. Susan Thorne examines some of the ways faculties of medicine are coping with change. In the brave new world of medical education, schools are combining classes for medical students and other health professionals, seeking business alliances, encouraging attendance by full-tuition students from other countries and diversifying revenue bases through new programs, such as McGill''s new 5-year MD-MBA degree.     

How Daphnia cope with algae selected for inedibility in long- running microcosms

Macro video records of restrained feeding Daphnia enabled usto measure simultaneously carapace gape, claw rejection rate,filter limb beat rate, and mandible movement rate. We comparedthe effects of high and low concentrations of highly ediblealgae and of inedible algae, the latter selected by long-termDaphnia grazing in oligotrophic microcosms. Inedible algae slowedthe filtering process and influenced the carapace gape (wideningat low concentration and narrowing at high), but did not affectthe rejection rate.     

How the roots contribute to the ability of Phaseolus vulgaris L. to cope with chilling-induced water stress

Intact plants and stem-girdled plants of Phaseolus vulgaris grown hydroponically were exposed to 5 degrees C for up to 4 d; stem girdling was used to inhibit the phloem transport from the leaves to the roots. After initial water stress, stomatal closure and an amelioration of root water transport properties allowed the plants to rehydrate and regain turgor. Chilling augmented the concentration of abscisic acid (ABA) content in leaves, roots and xylem sap. In intact plants stomatal closure and leaf ABA accumulation were preceded by a slight alkalinization of xylem sap, but they occurred earlier than any increase in xylem ABA concentration could be detected. Stem girdling did not affect the influence of chilling on plant water relations and leaf ABA content, but it reduced slightly the alkalinization of xylem sap and, principally, prevented the massive ABA accumulation in root tissues and the associated transport in the xylem that was observed in non-girdled plants. When the plants were defoliated just prior to chilling or after 10 h at 5 degrees C, root and xylem sap ABA concentration remained unchanged throughout the whole stress period. When the plants were chilled under conditions preventing the occurrence of leaf water deficit (i.e. at 100% relative humidity), there were no significant variations in endogenous ABA levels. The increase in root hydraulic conductance in chilled plants was a response neither to root ABA accretion, nor to some leaf-borne chemical signal transported downwards in the phloem, nor to low temperature per se, as indicated by the results of the experiments with defoliated or girdled plants and with plants chilled at 100% relative humidity. It was concluded that the root system contributed substantially to the bean's ability to cope with chilling-induced water stress, but not in an ABA-dependent manner.     

How to cope with negative estimates of components of variance in ecological field studies

Ecologists often need to estimate components of spatial or temporal variation. The most widely used method in ecology uses the observed and expected mean squares in an analysis of variance. A more general approach, which can be used for balanced and unbalanced designs, is based on residual maximal likelihood (REML). This method is less well known by ecologists and requires specialist software. If the design is balanced, the two methods are equivalent, except for one important respect: estimates from analysis of variance can be negative whereas REML estimates cannot. The purpose of this note is to point out a simple modification to the analyses of variance which yields the same estimates as REML for many of the designs commonly used in ecological studies. This modification has been available in the mathematical literature for over 30 years, but appears not to be well known amongst ecologists. It is useful in many cases of balanced analytical designs.     

How sulphate-reducing microorganisms cope with stress: lessons from systems biology

Sulphate-reducing microorganisms (SRMs) are a phylogenetically diverse group of anaerobes encompassing distinct physiologies with a broad ecological distribution. As SRMs have important roles in the biogeochemical cycling of carbon, nitrogen, sulphur and various metals, an understanding of how these organisms respond to environmental stresses is of fundamental and practical importance. In this Review, we highlight recent applications of systems biology tools in studying the stress responses of SRMs, particularly Desulfovibrio spp., at the cell, population, community and ecosystem levels. The syntrophic lifestyle of SRMs is also discussed, with a focus on system-level analyses of adaptive mechanisms. Such information is important for understanding the microbiology of the global sulphur cycle and for developing biotechnological applications of SRMs for environmental remediation, energy production, biocorrosion control, wastewater treatment and mineral recovery.     

How the Enga cope with frost: Responses to climatic perturbations in the Central Highlands of New Guinea

The adaptive strategy of a population of New Guinea highland subsistence farmers is considered in the light of events surrounding a series of severe frosts experienced in 1972. Coping with frost is seen to be a critical preoccupation for all Enga, and agricultural mounding a universal response, adequate to deal with the mild frosts of Central Enga country below 2250 m but insufficient above. There, among the Fringe Enga, a sequence of responses at three different levels may be identified. These may be called the local, intraregional, and extraregional levels because of their progressively wider geographical spread in agricultural activity and attendant increased population mobility. A correspondence is indicated between response level and frost intensity. This response, while effective, is being modified through cropping innovations and disrupted by a colonial situation. Further, at higher levels, it is incompatible with the prescribed course of political and economic development.     

How mothers cope with the death of a twin or higher multiple.

Estimates suggest up to 15% of multiples grow up as singleton survivors. Few studies have reported how bereaved multiple birth mothers with a surviving multiple cope with their bereavement. Using the population-based Western Australian Twin Child Health study database and other sources, we interviewed 66 bereaved mothers with at least one surviving multiple. For many, this contact was the first acknowledgement of their status as multiple birth mothers since their loss. The Beck Depression Inventory 2nd Edition (BDI) showed significant reduction in depression between the time of loss and our interview. For mothers as a group there was a high correlation between current and retrospective BDI, and retrospective BDI and all three Perinatal Grief Scales (PGS). There was a significant correlation between the three grief factors on the PGS. When subdivided, this held for mothers who suffered a loss at or before the neonatal period, but not for those whose loss occurred later. Bereaved mothers of multiples scored significantly higher on the PGS than the PGS norm for bereaved mothers of singletons, which we attribute to others not acknowledging their grief, and/or recruitment differences. There were no significant differences in PGS scores related to cause, the time since death, or sibling number or age. Spiritual beliefs and finding meaning in loss were positively related to scores for adjustment and acceptance. Although traumatised, most mothers accommodated their losses meaningfully in their lives. Their own support recommendations are included.