Is Carrying Feathers a Sexually Selected Trait in House Sparrows?

Males in several avian groups carry specialised materials as part of their courtship display. Females may vary their investment in reproduction in relation to their mates' attractiveness. The house sparrow (Passer domesticus) population on Dassen Island, South Africa, builds domed nests in the branches of trees. These nests are more or less spherical structures with a deep cup lined largely with feathers. When males collect feathers, they call to females and display the feather before it is added to the nest. We examined whether carrying feathers provides females with an index of male quality, which correlates with their subsequent investment in parental care. Additionally, we studied the potential importance of feathers in nest insulation. Feathers were collected mainly by males. Males also brought larger feathers, and deposited more feathers in nests, than females. Number of trips with feathers – which increased after feathers were experimentally removed from nests – and number of feathers brought varied among males. Volume of feathers influenced females' investment in reproduction and positively correlated with clutch size and chick feeding rates. We found more feathers during incubation and immediately after chicks hatched, when nest heat requirements peak. Furthermore, number of trips with feathers and number and size of feathers were greater during incubation. Our results suggest that this feather‐carrying behaviour by male house sparrows influences maternal reproduction investment and could be a kind of parental care per se by supplementing nest insulation.     

Trait Associations across Evolutionary Time within a Drosophila Phylogeny: Correlated Selection or Genetic Constraint?

Traits do not evolve independently. To understand how trait changes under selection might constrain adaptive changes, phenotypic and genetic correlations are typically considered within species, but these capture constraints across a few generations rather than evolutionary time. For longer-term constraints, comparisons are needed across species but associations may arise because of correlated selection pressures rather than genetic interactions. Implementing a unique approach, we use known patterns of selection to separate likely trait correlations arising due to correlated selection from those reflecting genetic constraints. We examined the evolution of stress resistance in >90 Drosophila species adapted to a range of environments, while controlling for phylogeny. Initially we examined the role of climate and phylogeny in shaping the evolution of starvation and body size, two traits previously not examined in this context. Following correction for phylogeny only a weak relationship between climate and starvation resistance was detected, while all of the variation in the relationship between body size and climate could be attributed to phylogeny. Species were divided into three environmental groups (hot and dry, hot and wet, cold) with the expectation that, if genetic correlations underpin trait correlations, these would persist irrespective of the environment, whereas selection-driven evolution should produce correlations dependent on the environment. We found positive associations between most traits in hot and dry environments coupled with high trait means. In contrast few trait correlations were observed in hot/wet and cold environments. These results suggest trait associations are primarily driven by correlated selection rather than genetic interactions, highlighting that such interactions are unlikely to limit evolution of stress resistance.     

Trait selection in flowering plants: how does sexual selection contribute?

By highlighting and merging the frameworks of sexual selectionenvisioned by Arnold (1994) and Murphy (1998), we discuss howsexual selection can occur in plants even though individualsdo not directly interact. We review studies on traits that influencepollen export and receipt in a variety of hermaphroditic andgynodioecious plants with the underlying premise that pollinationdynamics influences mate acquisition. Most of the studies reviewedfound that phenotypes that enhance pollen export are in harmonywith those that enhance pollen receipt suggesting that in manycases pollinator visitation rates limit both male and femalefunction. In contrast, fewer traits were under opposing selection;but when they were, the traits most often were associated withenhancing the specific aspects of a given sex function. Ourreview helps clarify and illustrate why sexual selection canbe a component of trait evolution in hermaphrodite plants.     

Is Catalytic Activity of Chaperones a Selectable Trait for the Emergence of Heat Shock Response?

Although heat shock response is ubiquitous in bacterial cells, the underlying physical chemistry behind heat shock response remains poorly understood. To study the response of cell populations to heat shock we employ a physics-based ab initio model of living cells where protein biophysics (i.e., folding and protein-protein interactions in crowded cellular environments) and important aspects of proteins homeostasis are coupled with realistic population dynamics simulations. By postulating a genotype-phenotype relationship we define a cell division rate in terms of functional concentrations of proteins and protein complexes, whose Boltzmann stabilities of folding and strengths of their functional interactions are exactly evaluated from their sequence information. We compare and contrast evolutionary dynamics for two models of chaperon action. In the active model, foldase chaperones function as nonequilibrium machines to accelerate the rate of protein folding. In the passive model, holdase chaperones form reversible complexes with proteins in their misfolded conformations to maintain their solubility. We find that only cells expressing foldase chaperones are capable of genuine heat shock response to the increase in the amount of unfolded proteins at elevated temperatures. In response to heat shock, cells’ limited resources are redistributed differently for active and passive models. For the active model, foldase chaperones are overexpressed at the expense of downregulation of high abundance proteins, whereas for the passive model; cells react to heat shock by downregulating their high abundance proteins, as their low abundance proteins are upregulated.     

Use of a Novel Probiotic Formulation to Alleviate Lactose Intolerance Symptoms—a Pilot Study

Probiotics and Antimicrobial Proteins - Lactose intolerance is a common condition caused by lactase deficiency and may result in symptoms of lactose malabsorption (bloating, flatulence, abdominal...     

Production of pectolytic enzymes – a review

Pectolytic enzymes play an important role in food processing industries and alcoholic beverage industries. These enzymes degrade pectin and reduce the viscosity of the solution so that it can be handled easily. These enzymes are mainly synthesized by plants and microorganisms. Aspergillus niger is used for industrial production of pectolytic enzymes. This fungus produces polygalacturonase, polymethylgalacturonase and pectinlyase. This review mainly concerns with the production of pectolytic enzymes using different carbon sources. It also deals with the effect of operating parameters such as temperature, aeration rate, agitation and type of fermentation on the production of these enzymes.     

Water-Stress-Induced Ethylene Production in Wheat : A Fact or Artifact?

Effects of water stress on ethylene evolution from excised leaf segments and intact plants of wheat (Triticum aestivum L. cv Katepwa) were studied. Excised leaf segments of 8 day or 6 week old plants were dried until they lost 8% of their fresh weight (water potential about −2.3 megapascals). These and nondried control leaf segments (water potential about −1.0 megapascal) were sealed in glass tubes, and their ethylene production rates were compared by head space analysis via gas-chromatography. The dried leaves of both ages produced significantly more ethylene than the corresponding controls. However, when 6 week old intact plants were water-stressed by withholding water supply, and their ethylene production measured using a continuousflow system, no increase in ethylene was deteceted despite a drop in water potential to −2.9 megapascals over 6 days. Even the leaf segments excised from plants that had been subjected to water stress for 2, 4, or 6 days produced no more ethylene (in sealed tubes) than the leaves from well-watered plants. In fact, the ethylene production by these segments decreased with the increase in the severity of stress experienced by the plants. The results show that the commonly reported overproduction of ethylene by excised leaves subjected to rapid drying represents an artifact, which has little relevance to the water stress responses of intact wheat plants.     

Is Disrupted Nucleotide-Substrate Cooperativity a Common Trait for Cushing's Syndrome Driving Mutations of Protein Kinase A?

Somatic mutations in the PRKACA gene encoding the catalytic α subunit of protein kinase A (PKA-C) are responsible for cortisol-producing adrenocortical adenomas. These benign neoplasms contribute to the development of Cushing's syndrome. The majority of these mutations occur at the interface between the two lobes of PKA-C and interfere with the enzyme's ability to recognize substrates and regulatory (R) subunits, leading to aberrant phosphorylation patterns and activation. Rarely, patients with similar phenotypes carry an allosteric mutation, E31V, located at the C-terminal end of the αA-helix and adjacent to the αC-helix, but structurally distinct from the PKA-C/R subunit interface mutations. Using a combination of solution NMR, thermodynamics, kinetic assays, and molecular dynamics simulations, we show that the E31V allosteric mutation disrupts central communication nodes between the N- and C- lobes of the enzyme as well as nucleotide-substrate binding cooperativity, a hallmark for kinases' substrate fidelity and regulation. For both orthosteric (L205R and W196R) and allosteric (E31V) Cushing’s syndrome mutants, the loss of binding cooperativity is proportional to the density of the intramolecular allosteric network. This structure–activity relationship suggests a possible common mechanism for Cushing's syndrome driving mutations in which decreased nucleotide/substrate binding cooperativity is linked to loss in substrate fidelity and dysfunctional regulation.     

Used Frying Oil: A Proper Feedstock for Biodiesel Production?

Used frying oil seems to be an economically viable and environmentally attractive alternative for biodiesel production, but the acceptance and successful use of this and other biodiesels obtained from waste materials require careful evaluation of its fuel properties and impurities. Herein, we show that biodiesel made from used frying soybean oil display overall quality comparable to those obtained from the fresh oil as measured by standard parameters of fuel quality such as induction period, acid number, heat of combustion, and iodine value as well as at the molecular level via profiles of intact and oxidized fatty acid methyl esters. These profiles were obtained directly from the biodiesel samples by easy ambient sonic spray ionization mass spectrometry. An artificial antioxidant, N,N??-di-sec-butyl-p-phenylenediamine, was shown to significantly increase the oxidative stability of the used frying oil biodiesel at trace level.     

Genetics: still a discipline?

In the institutional sense of the term "discipline" (laboratories, societies, congresses, curricula, etc.), genetics remains a discipline. In the intellectual sense of the term (consensus on a definite array of concepts, methods and theoretical purposes), it is doubtful that genetics is still a discipline. At first, molecular biology seemed to have introduced an unequivocal structural (or molecular) definition of the gene: a definite sequence of nucleotides that code for a protein. In fact, as it appears in retrospect, this was not the case. Even in 1961, when Jacob and Monod proposed their first model of genetic regulation in bacteria, there was no possibility of constructing a non equivocal concept of the gene. More recent developments in molecular genetics have made this situation worse. There is no possible definition of the gene as a general category. The reasons why biologists keep the word are pragmatic rather than theoretical: communication among scientists, economic interests and ideology.     

Heterochromatin: a meiotic matchmaker?

During meiosis, the pairing of chromosomes is crucial for a successful partitioning of the genetic material and its transmission into the developing gamete. The classical view of meiotic pairing involves recombination between homologues as an integral part of the pairing mechanism. But, in cases where no recombination occurs, how do chromosome partners find one another? And how do they pair up and then segregate appropriately? Recently, a combination of molecular genetics and fluorescence in situ hybridization appears to have provided an answer to these questions by demonstrating a crucial role for heterochromatin in chromosome pairing.     

Gestational diabetes: a non-entity?

Screening for gestational diabetes is commonly recommended despite the absence of a common definition of gestational diabetes. Furthermore, there is no consensus about management or treatment. Those who recommend screening do so largely on the basis of fetal morbidity, which seems to be predominantly "macrosomia"--another term without an agreed definition. The implications of macrosomia in terms of actual morbidity are also not clear. R J Jarrett reviews the history of the subject and concludes that gestational diabetes is simply impaired glucose tolerance temporally associated with pregnancy. Its main importance is as a predictor of subsequent non-insulin dependent diabetes, but it fails the major tests for a condition suitable for a screening programme.