Inorganic carbon acquisition in algal communities: are the laboratory data relevant to the natural ecosystems?

Most of the experimental work on the effects of ocean acidification on the photosynthesis of algae has been performed in the laboratory using monospecific cultures. It is frequently assumed that the information obtained from these cultures can be used to predict the acclimation response in the natural environment. CO(2) concentration is known to regulate the expression and functioning of the CCMs in the natural communities; however, ambient CO(2) can become quite variable in the marine ecosystems even in the short- to mid-term. We propose that the degree of saturation of the photosynthesis for a given algal community should be defined in relation to the particular characteristics of its habitat, and not only in relation to its taxonomic composition. The convenience of high CO(2) experiments to infer the degree of photosynthesis saturation by CO(2) in the natural algal communities under the present ocean conditions, as well as its trend in a coming future is discussed taking into account other factors such as the availability of light and nutrients, and seasonality.     

Do the microorganisms from laboratory culture spent growth medium affect house dust mite fitness and microbiome composition?

The interaction of house dust mites(HDM)and microorganisms is the key factor in the survival of these mites in human-made environments.Spent growth medium(SPGM)provides the rest of the dict,along with dead mite bodies and microorganisms.SPGM represents a source of microorganisms for the recolonization of mite food and the mite digestive tract.An experiment was performed to observe how adding SPGM to the HDM diet affects HDM population growth,the microbiome composition and the microbial respiration in microcosms.We analyzed American house dust mite(Dermatophagoides farinae)and European house dust mite(Dermatophagoides pleronyssinus)originating from control diets and diets treated with an extract of SPGM from 1-and 3-month-old mite cultures.The microbiome was described using 16S and 18S barcode sequencing.The composition of the bacterial and fiungal microbiomes differed between the HDM species,but the SPGM treatment influenced only the bacterial profile of D.farinae.In the D.farinae microbiome of specimens on SPGM-treated dicts compared to those of the control situation,the Lactobacillus profile decreased,while the Candinium,Staphylococ-cus,Acinetobacter,and Sphingomonas profiles increased.The addition of SPGM extract decreased the microbial respiration in the microcosms with and without mites in almost all cascs.Adding SPGM did not influence the population growth of D.farinae,but it had a variable effect on D.pteronyssimus.The results indicated that the HDM are marginally influenced by the microorganisms in their feces.     

How strong are side chain interactions in the folding intermediate?

Influence of 12 nonpolar amino acids residues from the hydrophobic core of apomyoglobin on stability of its native state and folding intermediate was studied. Six of the selected residues are from the A, G and H helices; these are conserved in structure of the globin family, although nonfunctional, that is, not involved in heme binding. The rest are nonconserved hydrophobic residues that belong to the B, C, D, and E helices. Each residue was substituted by alanine, and equilibrium pH‐induced transitions in apomyoglobin and its mutants were studied by circular dichroism and fluorescent spectroscopy. The obtained results allowed estimating changes in their free energy during formation of the intermediate state. It was first shown that the strength of side chain interactions in the apomyoglobin intermediate state amounts to 15–50% of that in its native state for conserved residues, and practically to 0% for nonconserved residues. These results allow a better understanding of interactions occurring in the intermediate state and shed light on involvement of certain residues in protein folding at different stages.     

How biologically relevant are interaction-based modules in protein networks?

By applying a graph-based algorithm to yeast protein-interaction networks we have extracted modular structures and show that they can be validated using information from the phylogenetic conservation of the network components. We show that the module cores, the parts with the highest intramodular connectivity, are biologically relevant components of the networks. These constituents correlate only weakly with other levels of organization. We also discuss how such structures could be used for finding targets for antimicrobial drugs.     

How is autonomic nervous system activity in subjects who are sleepy but are unable to sleep in the daytime?

We investigated changes in the activity of the autonomic nervous system (ANS) in the relaxed condition in subjects who felt sleepy, but were unable to sleep. A total of 1021 subjects underwent daytime polysomnography. The sleep latency (SL) and the visual analog scale (VAS) were used to assess “immediate” objective and subjective sleepiness, respectively. The subjects were assigned to an “Alert-Alert” group (VAS ≤ 25 mm, SL ≥ 8 min), a “Sleepy-Alert” group (VAS ≥ 75 mm, SL ≥ 8 min), or a “Sleepy-Sleepy” group (VAS ≥ 75 mm, SL ≤ 4 min). In order to assess the ANS, the spectral analysis and the geometric method were used. The ANS data collected during the relaxed condition (after lights off, post-LO) was compared to that obtained during the control condition (before lights off, pre-LO). From the spectral analysis, a significant decrease of sympathetic function and an increase of parasympathetic function at post-LO in the Sleepy-Sleepy group, a tendency for sympathetic function decrease at post-LO in the Alert-Alert group, and no significant changes to sympathetic and parasympathetic function in the Sleepy-Alert group were observed. The results from the geometric method supported the results of the spectral analysis in the Alert-Alert group and the Sleepy-Sleepy group. The results of this study suggest that the ANS plays a role in individuals who are unable to sleep even though they feel sleepy and are given the opportunity to sleep.

     

How context dependent are species interactions?

The net effects of interspecific species interactions on individuals and populations vary in both sign (?, 0, +) and magnitude (strong to weak). Interaction outcomes are context‐dependent when the sign and/or magnitude change as a function of the biotic or abiotic context. While context dependency appears to be common, its distribution in nature is poorly described. Here, we used meta‐analysis to quantify variation in species interaction outcomes (competition, mutualism, or predation) for 247 published articles. Contrary to our expectations, variation in the magnitude of effect sizes did not differ among species interactions, and while mutualism was most likely to change sign across contexts (and predation least likely), mutualism did not strongly differ from competition. Both the magnitude and sign of species interactions varied the most along spatial and abiotic gradients, and least as a function of the presence/absence of a third species. However, the degree of context dependency across these context types was not consistent among mutualism, competition and predation studies. Surprisingly, study location and ecosystem type varied in the degree of context dependency, with laboratory studies showing the highest variation in outcomes. We urge that studying context dependency per se, rather than focusing only on mean outcomes, can provide a general method for describing patterns of variation in nature.     

Does cholinesterase participate in the intercellular interactions in pollen-pistil system?

Hydrolysis of acetylthiocholine and butyrylthiocholine has been observed in aqueous extracts from petunia pollen and pistils. The reproductive organs of self-compatible clone showed a higher rate of choline ester hydrolysis than those of self-incompatible clone. The highest rate of acetylthiocholine hydrolysis blocked by the cholinesterase inhibitors (physostigmine and neostigmine) was characteristic for the pollen of self-compatible clone. The incomplete (25 - 40 %) inhibition of hydrolysis in pistil extracts of self-compatible clone suggests the presence of unspecific esterases. The eight-fold lower hydrolysis was observed in the pistils of self-incompatible clone as compared to the pistils of compatible clone; neostigmine completely blocked this low hydrolytic activity. The treatment of flower buds with physostigmine and neostigmine (10-5 - 10-3 M) decreased the seed production by 10 - 20 % in compatible clone. When the surfaces of pistil stigmae were treated with physostigmine and neostigmine (10-5 - 10-3 M) before pollination, the seed formation was inhibited by 95 % after both self- and cross-pollination. This revised version was published online in July 2006 with corrections to the Cover Date.     

A restatement of the natural science evidence base relevant to the control of bovine tuberculosis in Great Britain?

Bovine tuberculosis (bTB) is a very important disease of cattle in Great Britain, where it has been increasing in incidence and geographical distribution. In addition to cattle, it infects other species of domestic and wild animals, in particular the European badger (Meles meles). Policy to control bTB is vigorously debated and contentious because of its implications for the livestock industry and because some policy options involve culling badgers, the most important wildlife reservoir. This paper describes a project to provide a succinct summary of the natural science evidence base relevant to the control of bTB, couched in terms that are as policy-neutral as possible. Each evidence statement is placed into one of four categories describing the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.     

How robust are laboratory measures of growth hormone status?

Biochemical assessment of growth hormone (GH) status is required in both suspected GH deficiency and GH excess. GH secretion can either be measured through investigation of the pituitary or by monitoring markers that change as a consequence of GH action on its target tissues. The two most widely used and, to date, best validated biochemical parameters are immunoassay measurement of either human GH (hGH) or insulin-like growth factor (IGF)-I. The fundamental difference between measurement of hGH and IGF-I is that the first reflects GH secretion while the second reflects GH action. However, because GH secretion is pulsatile in nature, random blood sampling for determination of hGH levels is only minimally informative. Analytical methods for measuring GH and IGF-I show considerable between-method variability. Since these parameters are used in establishing diagnoses and in monitoring GH-related diseases, the endocrinologist should be aware of the specifications and limitations of the analytical methods available.     

Bacterial cooperation in the wild and in the clinic: Are pathogen social behaviours relevant outside the laboratory?

Individual bacterial cells can communicate via quorum sensing, cooperate to harvest nutrients from their environment, form multicellular biofilms, compete over resources and even kill one another. When the environment that bacteria inhabit is an animal host, these social behaviours mediate virulence. Over the last decade, much attention has focussed on the ecology, evolution and pathology of bacterial cooperation, and the possibility that it could be exploited or destabilised to treat infections. But how far can we really extrapolate from theoretical predictions and laboratory experiments to make inferences about ‘cooperative’ behaviours in hosts and reservoirs? To determine the likely importance and evolution of cooperation ‘in the wild’, several questions must be addressed. A recent paper that reports the dynamics of bacterial cooperation and virulence in a field experiment provides an excellent nucleus for bringing together key empirical and theoretical results which help us to frame – if not completely to answer – these questions.     

What are the most relevant parameters for malnutrition in nursing homes?

Prevention of malnutrition is an important issue among older nursing homes residents. From this perspective it is crucial that malnutrition is detected in an early stage. Hence, parameters and tools are required that are suitable for these institutions. Based on recent publications an assessment has been made to identify which parameters are most relevant in nursing homes. The literature study indicates that a wide scope of parameters exists for screening of malnutrition. Only a limited number has been studied in the elderly. In addition, more complicated parameters and tools have not revealed substantial added value to relatively simple parameters, such as foodrecords, weight loss and Body Mass Index.     

How are humans related to other primates? A guided inquiry laboratory for undergraduate students

Understanding that phylogenies depict the evolutionary history of species is a critical concept for undergraduate biology students. We present an inquiry-based laboratory exercise exploring this concept in the context of the human phylogeny. This activity reinforces several important biological concepts and skills. Bolstered concepts include that evolution is descent with modification, that evolution is a genetic process, and that humans are closely related to apes. In terms of thinking skills, the lab gives students practice with hypothetical-deductive thinking, quantifying patterns from complex data, and evaluating evidence.