Diving insects boost their buoyancy bubbles

Backswimmers (Notonectidae) are common diving insects found around the world that exploit the mid-water zone for predation--they breathe by using an air bubble collected at the surface. Here we show that backswimmers achieve prolonged periods of neutral buoyancy by using oxygen stored in their haemoglobin to stabilize the volume of the bubble as they breathe from it. This enables them to maintain their position in the water column without continually swimming.     

Glioma stem cells promote radioresistance by preferential activation of the DNA damage response

Ionizing radiation represents the most effective therapy for glioblastoma (World Health Organization grade IV glioma), one of the most lethal human malignancies, but radiotherapy remains only palliative because of radioresistance. The mechanisms underlying tumour radioresistance have remained elusive. Here we show that cancer stem cells contribute to glioma radioresistance through preferential activation of the DNA damage checkpoint response and an increase in DNA repair capacity. The fraction of tumour cells expressing CD133 (Prominin-1), a marker for both neural stem cells and brain cancer stem cells, is enriched after radiation in gliomas. In both cell culture and the brains of immunocompromised mice, CD133-expressing glioma cells survive ionizing radiation in increased proportions relative to most tumour cells, which lack CD133. CD133-expressing tumour cells isolated from both human glioma xenografts and primary patient glioblastoma specimens preferentially activate the DNA damage checkpoint in response to radiation, and repair radiation-induced DNA damage more effectively than CD133-negative tumour cells. In addition, the radioresistance of CD133-positive glioma stem cells can be reversed with a specific inhibitor of the Chk1 and Chk2 checkpoint kinases. Our results suggest that CD133-positive tumour cells represent the cellular population that confers glioma radioresistance and could be the source of tumour recurrence after radiation. Targeting DNA damage checkpoint response in cancer stem cells may overcome this radioresistance and provide a therapeutic model for malignant brain cancers.     

Eastern Pacific cooling and Atlantic overturning circulation during the last deglaciation

Surface ocean conditions in the equatorial Pacific Ocean could hold the clue to whether millennial-scale global climate change during glacial times was initiated through tropical ocean-atmosphere feedbacks or by changes in the Atlantic thermohaline circulation. North Atlantic cold periods during Heinrich events and millennial-scale cold events (stadials) have been linked with climatic changes in the tropical Atlantic Ocean and South America, as well as the Indian and East Asian monsoon systems, but not with tropical Pacific sea surface temperatures. Here we present a high-resolution record of sea surface temperatures in the eastern tropical Pacific derived from alkenone unsaturation measurements. Our data show a temperature drop of approximately 1 degrees C, synchronous (within dating uncertainties) with the shutdown of the Atlantic meridional overturning circulation during Heinrich event 1, and a smaller temperature drop of approximately 0.5 degrees C synchronous with the smaller reduction in the overturning circulation during the Younger Dryas event. Both cold events coincide with maxima in surface ocean productivity as inferred from 230Th-normalized carbon burial fluxes, suggesting increased upwelling at the time. From the concurrence of equatorial Pacific cooling with the two North Atlantic cold periods during deglaciation, we conclude that these millennial-scale climate changes were probably driven by a reorganization of the oceans' thermohaline circulation, although possibly amplified by tropical ocean-atmosphere interaction as suggested before.     

Highly effective SNP-based association mapping and management of recessive defects in livestock

The widespread use of elite sires by means of artificial insemination in livestock breeding leads to the frequent emergence of recessive genetic defects, which cause significant economic and animal welfare concerns. Here we show that the availability of genome-wide, high-density SNP panels, combined with the typical structure of livestock populations, markedly accelerates the positional identification of genes and mutations that cause inherited defects. We report the fine-scale mapping of five recessive disorders in cattle and the molecular basis for three of these: congenital muscular dystony (CMD) types 1 and 2 in Belgian Blue cattle and ichthyosis fetalis in Italian Chianina cattle. Identification of these causative mutations has an immediate translation into breeding practice, allowing marker assisted selection against the defects through avoidance of at-risk matings.     

Bacterial adhesion and biofilms on surfaces

Bacterial adhesion has become a significant problem in industry and in the domicile,and much research has been done for deeper understanding of the processes involved.A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle,has been described and modified many times.The biofilm growth cycle encompasses bacterial adhesion at all levels,starting with the initial physical attraction of bacteria to a substrate,and ending with the eventual liberation of cell dusters from the biofilm matrix.When describing bacterial adhesion one is simply describing one or more stages of biofilm development,neglecting the fact that the population may not reach maturity.This article provides an overview of bacterial adhesion.cites examples of how bac-terial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive prop-erties of bacteria.     

Regulation of innate and adaptive immune responses by MAP kinase phosphatase 5

Mitogen-activated protein (MAP) kinases are essential regulators in immune responses, and their activities are modulated by kinases and phosphatases. MAP kinase phosphatase (MKP) is a family of dual-specificity phosphatases whose function is evolutionarily conserved. A number of mammalian MKPs have been identified so far, but their specific physiological functions in negative regulation of MAP kinases have not been genetically defined. Here we examine innate and adaptive immune responses in the absence of MKP5. JNK activity was selectively increased in Mkp5 (also known as Dusp10)-deficient mouse cells. Mkp5-deficient cells produced greatly enhanced levels of pro-inflammatory cytokines during innate immune responses and exhibited greater T-cell activation than their wild-type counterparts. However, Mkp5-deficient T cells proliferated poorly upon activation, which resulted in increased resistance to experimental autoimmune encephalomyelitis. By contrast, Mkp5-deficient CD4(+) and CD8(+) effector T cells produced significantly increased levels of cytokines compared with wild-type cells, which led to much more robust and rapidly fatal immune responses to secondary infection with lymphocytic choriomeningitis virus. Therefore, MKP5 has a principal function in both innate and adaptive immune responses, and represents a novel target for therapeutic intervention of immune diseases.     

Environmental biology: heat reward for insect pollinators

In neotropical forests, adults of many large scarab beetle species spend most of their time inside the floral chambers of heat-producing flowers, where they feed and mate throughout the night and rest during the following day, before briefly flying to another flower. Here we measure floral temperatures in Philodendron solimoesense (Araceae) in French Guiana and the respiration rates of Cyclocephala colasi beetles at floral and ambient temperatures, and show that the the beetles' extra energy requirements for activity are 2.0-4.8 times greater outside the flower than inside it. This finding indicates that heat produced by the flower constitutes an important energy reward to pollinators, allowing them to feed and mate at a fraction of the energy cost that would be required outside the flower.