How do bacteria sense and respond to low temperature?

Rigidification of the membrane appears to be the primary signal perceived by a bacterium when exposed to low temperature. The perception and transduction of the signal then occurs through a two-component signal transduction pathway consisting of a membrane-associated sensor and a cytoplasmic response regulator and as a consequence a set of cold-regulated genes are activated. In addition, changes in DNA topology due to change in temperature may also trigger cold-responsive mechanisms. Inducible proteins thus accumulated repair the damage caused by cold stress. For example, the fluidity of the rigidified membrane is restored by altering the levels of saturated and unsaturated fatty acids, by altering the fatty acid chain length, by changing the proportion of cis to trans fatty acids and by changing the proportion of anteiso to iso fatty acids. Bacteria could also achieve membrane fluidity changes by altering the protein content of the membrane and by altering the levels of the type of carotenoids synthesized. Changes in RNA secondary structure, changes in translation and alteration in protein conformation could also act as temperature sensors. This review highlights the various strategies by which bacteria senses low temperature signal and as to how it responds to the change.     

Wild bees respond complementarily to ‘high-quality’ perennial and annual habitats of organic farms in a complex landscape

Agricultural intensification leads to large-scale loss of habitats offering food and nesting sites for bees. This has resulted in a severe decline of wild bee diversity and abundance during the past decades. There is an urgent need for cost-effective conservation measures to mitigate this decline. We analysed the impact of five different high-quality habitats on species richness and abundance of wild bees in a complex landscape of north-western Switzerland at six sites. The five habitat types included 45 plots situated on eight organic farms and were composed of 16 low-input meadows, six low-input pastures, seven herbaceous strips adjacent to hedges, five sown flower strips and eleven organic cereal fields. All of them are financially subsidised by the Swiss agri-environmental scheme. Wild bees were sampled between the end of April and end of August 2014 by using trio-pan traps and complementary sweep netting on these five habitat types. On 45 plots we recorded 3973 bee specimens, belonging to 91 species, 16 of which are red listed, revealing a high bee species richness in the study area. Wild bee species richness and abundance were best explained by habitat type, number of flowering plants and site. A strong relationship of increasing number of flowering plants and bee species richness and abundance was found. Grassland habitats, especially low-input meadows, harboured the highest species richness and abundances. Organic cereal fields showed a potential to conserve bee species relevant to nature conservation (harbouring exclusively two red list species and four rare species). Ordination analysis of the bee communities showed a relative dissimilarity between the habitat types and indicates their complementary effects to benefit the diversity of wild bees. Our results demonstrate that a matrix of low-input habitats are needed to sustain rich assemblages of wild bees in agroecosystems.     

The emission of floral scent from Lilium ‘siberia’ in response to light intensity and temperature

Floral scent is an important part of volatile compounds emitted from plants, and is influenced by many environmental factors. In this study, the floral scent emitted from Lilium ‘siberia’, a common breed of lily, was collected by dynamic headspace at different levels of light intensity (0, 100, 300, 600, 1,000, and 1,500 μmol m^?2 s^?1) and temperature (10, 20, 30, and 40 °C). Using the automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) technique, the components and release amounts were subsequently identified to investigate the influence of light and temperature on the emission of floral scent. The results revealed that the numbers and release amounts of floral scent components were significantly influenced by light intensity and temperature, showing the similar pattern: first increasing and then decreasing. After light intensity treatment, the maximum numbers and release amounts mainly appeared at 600 and 1,000 μmol m^?2 s^?1. For temperature treatment, 30 °C resulted in the highest numbers and release amounts of the floral scent components. At different levels of light intensity and temperature, terpenoid compounds showed the highest numbers and release amounts among the component categories. α-Ocimene and linalool were the two terpenoid compounds with the highest release amounts, and accounted for the highest proportion. The results obtained provide evidence that both light intensity and temperature trigger the emission of floral scent. The particular response mechanisms must be investigated in future research.     

Introduction to ‘Homology and convergence in nervous system evolution’

The origin of brains and central nervous systems (CNSs) is thought to have occurred before the Palaeozoic era 540 Ma. Yet in the absence of tangible evidence, there has been continued debate whether today''s brains and nervous systems derive from one ancestral origin or whether similarities among them are due to convergent evolution. With the advent of molecular developmental genetics and genomics, it has become clear that homology is a concept that applies not only to morphologies, but also to genes, developmental processes, as well as to behaviours. Comparative studies in phyla ranging from annelids and arthropods to mammals are providing evidence that corresponding developmental genetic mechanisms act not only in dorso–ventral and anterior–posterior axis specification but also in segmentation, neurogenesis, axogenesis and eye/photoreceptor cell formation that appear to be conserved throughout the animal kingdom. These data are supported by recent studies which identified Mid-Cambrian fossils with preserved soft body parts that present segmental arrangements in brains typical of modern arthropods, and similarly organized brain centres and circuits across phyla that may reflect genealogical correspondence and control similar behavioural manifestations. Moreover, congruence between genetic and geological fossil records support the notion that by the ‘Cambrian explosion’ arthropods and chordates shared similarities in brain and nervous system organization. However, these similarities are strikingly absent in several sister- and outgroups of arthropods and chordates which raises several questions, foremost among them: what kind of natural laws and mechanisms underlie the convergent evolution of such similarities? And, vice versa: what are the selection pressures and genetic mechanisms underlying the possible loss or reduction of brains and CNSs in multiple lineages during the course of evolution? These questions were addressed at a Royal Society meeting to discuss homology and convergence in nervous system evolution. By integrating knowledge ranging from evolutionary theory and palaeontology to comparative developmental genetics and phylogenomics, the meeting covered disparities in nervous system origins as well as correspondences of neural circuit organization and behaviours, all of which allow evidence-based debates for and against the proposition that the nervous systems and brains of animals might derive from a common ancestor.     

Gas valves,forests and global change: a commentary on Jarvis (1976) ‘The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field’

Microscopic turgor-operated gas valves on leaf surfaces—stomata—facilitate gas exchange between the plant and the atmosphere, and respond to multiple environmental and endogenous cues. Collectively, stomatal activities affect everything from the productivity of forests, grasslands and crops to biophysical feedbacks between land surface vegetation and climate. In 1976, plant physiologist Paul Jarvis reported an empirical model describing stomatal responses to key environmental and plant conditions that predicted the flux of water vapour from leaves into the surrounding atmosphere. Subsequent theoretical advances, building on this earlier approach, established the current paradigm for capturing the physiological behaviour of stomata that became incorporated into sophisticated models of land carbon cycling. However, these models struggle to accurately predict observed trends in the physiological responses of Northern Hemisphere forests to recent atmospheric CO₂ increases, highlighting the need for improved representation of the role of stomata in regulating forest–climate interactions. Bridging this gap between observations and theory as atmospheric CO₂ rises and climate change accelerates creates challenging opportunities for the next generation of physiologists to advance planetary ecology and climate science. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.     

Genetic and biochemical studies on perchloroethylene ‘in vitro’ and ‘in vivo’

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and ‘in vivo’ by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + β-naphthoflavone. PCE did not induce any genetic effect either ‘in vitro’ or ‘in vivo’. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.     

Genetics of resistance to Puccinia graminis tritici in ‘Chris’ and ‘W3746’ wheats

Summary Chris wheat possessed genes Sr5, Sr7a, Sr8a, Sr9g and Sr12. W3746, derived from the cross Chris/Baart, possessed Sr7a and Sr12. The response conferred by Sr7a was influenced by the genetic background. Although Sr7a or Sr12 alone conferred no observable resistance upon adult plants, the adult resistances of Chris and W3746 to predominant pathotypes appeared to be associated with the interaction of Sr7a and Sr12, or genes at closely linked loci.     

‘Classical’ and ‘non-classical’ reproductive steroids in fish

Summary The nature of the steroids secreted by gonads of fish differs significantly from those of the mammals. The classical teleost steroids, oestradiol, testosterone, 11-ketotestosterone and 17,20P, have been measured in a wide variety of teleosts but do not always reflect biological activities. There is increasing evidence that teleost gonads may produce a number of non-classical steroids which may play an important role in their reproductive biology. Such products include metabolites reduced at C5 to 5 or 5, at C3 to 3 or 3, or hydroxylated at 6-, 7-, or 21. Conjugation, as either glucuronides or sulphates, may contribute either to localization of action within the gonad or to production of pheromones during the immediate pre-spawning period. Although it is often possible only to measure the steroids for which assays are readily available, it is important to recognize that there may be production of steroids that are not detected by such assays, but which nevertheless play a major role in reproductive activity. In evolutionary terms, the teleost hydroxylases probably originated in the very early fishes and show parallels with their analogues in amphibians and mammals. Gene sequencing may reveal a possible common ancestor for all vertebrate 6, 7 and 11-hydroxylases.     

‘Mental’ in ‘southie’: Individual,family, and community responses to psychosis in South Boston

The deinstitutionalization of psychiatric patients is a deeply cultural as well as political task. It entails the sharing of responsibility for human distress with family and community. Consequently, the locus of social control has also shifted from psychiatric and medical expertise to community and legal institutions. Diagnosis and treatment models must be more compatible with lay explanatory models. This paper explores the various meanings of going mental and being mental in the white, working class, ethnic neighborhood of South Boston. The data are extracted from a study of the impact of deinstitutionalization on a cohort of middle-aged, psychiatric patients discharged from Boston State Hospital in the attempt to return them to community living. Individual, family, and community responses to, and interpretations of, the symptoms of mental distress are discussed. The study indicates that even seriously disturbed individuals are sensitive to cultural meanings and social cues regarding the perception, expression, and content of psychiatric episodes. While madness invariably disenfranchises, it does not necessarily deculturate the individual.     

Rethinking the ‘everyday’ in ‘ethnicity and everyday life’

While ‘ethnicity and everyday life’ is a familiar collocation, sociologists concerned with racism and ethnicity have not engaged very much with the extensive body of social theory that takes the ‘everyday’ as its central problematic. In this essay, I consider some of the ways in which the sociology of the everyday might be of use to those concerned with investigating ethnicity and racism. For its part, however, the sociology of the everyday has tended to be remarkably blind to the role played by racism and racialization in the modern world. It is thus no less crucial to consider how the experiences of racialized groups might help us rethink influential accounts of the everyday. To this end, I provide a discussion of pioneering texts by C. L. R. James and W. E. B. du Bois, both of whom were driven by their reflections on racism and resistance to recognize the everyday not as an unremarked context, but as, precisely, a problematic one.     

Problems in application of the terms ‘blastic’ and ‘thallic’ to modes of conidiogenesis in some onygenalean fungi

A woman suffering from acute tubulo-interstitial nephritis was admitted to the hospital ten days after deliberate intoxication by ingestion of Cortinarius orellanus. Orellanine, the main toxin responsible for orellanine poisoning, was detected in biological fluids and renal biopsies. It was assayed by direct spectrofluorimetry on two-dimensional thin-layer chromatograms after specific photodecomposition into orelline. The orellanine concentration was 6.12 mg/l in the plasma (10 days after ingestion). Orellanine levels in renal biopsies were 7 g per 25 mm³ of the first biopsy (13 days after ingestion) and 24 g per 8 mm³ of the second biopsy (6 months later).Taken in part from the doctorate thesis of S. Rapior.     

Fathers' care in context: ‘facultative,’ flexible fathers respond to work demands and child age,but not to alloparental help,in Cebu,Philippines

Current evolutionary theory conceptualizes fathers' childcare as highly facultative and likely contingent on a variety of local socioecological predictors. Much of the evolutionarily-motivated work on the predictors of paternal care has focused on smaller-scale societies, while similar, potentially complementary research in larger-scale societies has focused on theoretical frameworks from (e.g.) economics and developmental psychology. Due to the different emphases, relatively few studies have incorporated information on variables known to predict paternal care in one context with those known to predict it in the other. Here, we assess whether paternal care conforms to predictions derived from the facultative fathering hypothesis and life history theory in Cebu, the Philippines. We evaluated which of 6 variables—hours worked outside the home, age and number of children, number of other caregivers, family residence pattern, and fathers' educational attainment—predicted the number of hours fathers reported spending on 12 common caregiving tasks. Consistent with the basic premise of facultative fathering, men who worked more spent less time on childcare. Additionally, the time fathers spent on different types of caregiving reflected changes in demand as children age. However, alloparental care appears to be a complement to, rather than a substitute for, paternal care in this context, in contrast to the predictions of the facultative fathering hypothesis. We also found that men with more education reported spending more time on childcare, consistent with a caregiving strategy that emphasizes heavy investment in embodied capital across generations. Our data illustrate the context-specific nature of ‘facultative’ caregiving in humans, and highlight the importance of considering locally-relevant predictors when testing predictions derived from evolutionary theory.     

Odor discrimination of ‘cAMP-’ and ‘IP3-increasing’ odorants at high temperature and at high NaCl concentration in turtle olfactory system

The ability of the turtle olfactory system to discriminate between various cAMP- and IP₃-increasing odorants at high temperature and at high NaCl concentration in the olfactory bulb was examined by the cross-adaptation technique. The degrees of discrimination in high [Na⁺] solution were similar to those in normal Ringer's solution, suggesting that selectivities of receptors coupled with cAMP- and IP₃-dependent pathways are similar to those coupled with both cAMP- and IP₃-independent pathways. The mean values of the degree of discrimination among the IP₃-increasing odorants were higher than those among the cAMP-increasing odorants at high temperature and at high [Na⁺] concentration. The degrees of discrimination among the IP₃-increasing odorants at 40°C were greater than those at 25°C, while those among the cAMP-increasing odorants at 40°C were similar to those at 25°C, suggesting that the features of the receptors of cAMP-increasing odorants are different from those which respond to IP₃-increasing odorants.     

Local Environmental Knowledge,Talk, and Skepticism: Using ‘LES’ to Distinguish ‘LEK’ from ‘LET’ in Newfoundland

The actual evidence observed in studies of LEK (local environmental knowledge) is nearly always talk about the environment, or what we refer to as LET (local environmental talk), with the claim of studying LEK usually being built upon the implicit assumption that talk about the environment is the expression of knowledge about the environment. We suggest that it is critically important for researchers to question this assumption, especially when the distinction between LET and LEK is also emphasized by local people themselves. In the case we present here, residents of small fishing villages on the Northern Peninsula of Newfoundland are routinely skeptical about what other local residents say about the environment; that is, they engage in LES (local environmental skepticism). We suggest that paying explicit attention to LES can help distinguish LEK from LET.     

Is stomatal conductance optimized over both time and space in plant crowns? A field test in grapevine (Vitis vinifera)

Crown carbon gain is maximized for a given total water loss if stomatal conductance (g_s) varies such that the marginal carbon product of water (?A/?E) remains invariant both over time and among leaves in a plant crown, provided the curvature of assimilation rate (A) versus transpiration rate (E) is negative. We tested this prediction across distinct crown positions in situ for the first time by parameterizing a biophysical model across 14 positions in four grapevine crowns (Vitis vinifera), computing optimal patterns of g_s and E over a day and comparing these to the observed patterns. Observed water use was higher than optimal for leaves in the crown interior, but lower than optimal in most other positions. Crown carbon gain was 18% lower under measured g_s than under optimal g_s. Positive curvature occurred in 39.6% of cases due to low boundary layer conductance (g_bw), and optimal g_s was zero in 11% of cases because ?A/?E was below the target value at all g_s. Some conclusions changed if we assumed infinite g_bw, but optimal and measured E still diverged systematically in time and space. We conclude that the theory's spatial dimension and assumption of positive curvature require further experimental testing.     

Physiological and ecological responses to drought and heat stresses in Osmanthus fragrans ‘Boyejingui’

为了探讨植物对干旱、高温及协同胁迫的响应, 该研究以木犀(Osmanthus fragrans) ‘波叶金桂’为材料, 采用盆栽质量控水法模拟干旱胁迫(对照、轻度、中度和重度)和高温胁迫, 利用动态顶空气体循环吸附法和热脱附-气相色谱-质谱(TDS-GC-MS)联用技术对其挥发性有机化合物(VOCs)进行测定; 同时测定其非结构性碳(NSC)含量及次生代谢酶活性。结果表明: 干旱胁迫对‘波叶金桂’叶片NSC组分含量影响不显著; 可溶性糖和淀粉含量在高温胁迫下显著降低, 在协同胁迫后持续性下降, 重度协同胁迫下, 葡萄糖、果糖、蔗糖和淀粉分别比对照降低47.7%、46.4%、34.4%和38.2%。干旱胁迫和协同胁迫下3-羟基-3-甲基戊二酸单酰辅酶A还原酶(HMGR)、1-脱氧木酮糖-5-磷酸还原酶(DXR)活性表现出先上升后下降, 而脂氧合酶(LOX)活性表现出持续性上升趋势; 高温胁迫后, HMGR、DXR和LOX活性显著高于对照。干旱胁迫下萜烯类VOCs释放量表现出先上升后下降趋势, 中度干旱胁迫和高温胁迫下分别比对照高37.9%和32.3%; 协同胁迫下萜烯类释放量逐渐降低, 干旱、高温和协同胁迫诱导醛类释放量明显增加。上述结果表明: 干旱胁迫条件下, ‘波叶金桂’通过NSC进行自我渗透调节, 同时合成大量萜烯类化合物来提高抗旱性; ‘波叶金桂’调控萜烯类化合物合成以及绿叶挥发物(GLVs)的释放抵御高温胁迫; 协同胁迫下萜烯类化合物的合成途径受阻, ‘波叶金桂’提高GLVs合成与释放量抵御协同胁迫; 中度和重度协同胁迫导致‘波叶金桂’细胞膜严重受损, 自我调节能力降低。