Are the different hypotheses on the emergence of life as different as they seem?

This paper calls attention to a philosophical presupposition, coined here the continuity thesis which underlies and unites the different, often conflicting, hypotheses in the origin of life field. This presupposition, a necessary condition for any scientific investigation of the origin of life problem, has two components. First, it contends that there is no unbridgeable gap between inorganic matter and life. Second, it regards the emergence of life as a highly probable process. Examining several current origin-of-life theories. I indicate the implicit or explicit role played by the continuity thesis in each of them. In addition, I identify the rivals of the thesis within the scientific community — the almost miracle camp. Though adopting the anti-vitalistic aspect of the continuity thesis, this camp regards the emergence of life as involving highly improbable events. Since it seems that the chemistry of the prebiotic stages and of molecular self-organization processes rules out the possibility that life is the result of a happy accident, I claim that the almost miracle view implies in fact, a creationist position.     

What works in the field? A comparison of different interviewing methods in ethnobotany with special reference to the use of photographs

Ethnobotanists use a variety of interview techniques to collect ethnobotanical data. Drawing upon the results from a quantitative ethnobotanical study in five Yuracaré and Trinitario communities in the Bolivian Amazon, the pros and cons of the following methods are evaluated: (1) interviews in situ during transects, walk-in-the-woods, and homegarden sampling; and (2) interviews ex situ with fresh plant material, voucher specimens, or plant photographs as reference tools. Although the systematic use of plant photographs for ethnobotanical interviews is poorly documented in literature, the results show that indigenoùs participants in our study recognize significantly more plant species from photographs than from voucher specimens. It is argued that, especially in remote and isolated study sites, photographs might be advantageous over voucher specimens.     

Determination of the post mortem interval in skeletal remains by the comparative use of different physico-chemical methods: Are they reliable as an alternative to 14C?

The determination of the post-mortem interval (PMI) of skeletal remains is a challenging aspect in the forensic field. Previous studies focused their attention on different macroscopic and morphological aspects but a thorough and complete evaluation of the potential of chemical and physical analyses in this field of research has not been performed. In addition to luminol test and Oxford histology index (OHI) reported in a recent paper, widely spread and accessible methods based on physical aspect and chemical characteristics of skeletal remains have been investigated as potential alternatives to dating by determination of ¹⁴C.The investigation was performed on a total of 24 archeological and forensic bone samples with known PMI, with inductively coupled plasma optical emission spectrometer (ICP-OES), inductively coupled plasma quadruple mass spectrometry (ICP-MS), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray analysis (EDX), powder X-ray diffraction analysis (XRPD) and scanning electron microscopy (SEM). Finally, the feasibility of such alternative methods was discussed. Some results such as carbonates/phosphates ratio from FT-IR, the amounts of organic and inorganic matter by EDX, crystallite sizes with XRPD, and surface morphology obtained by SEM, showed significant trends along with PMI. Though, from a chemical point of view cut-off values and gold-standard methods still present challenges, and rather different techniques together can provide useful information toward the assessment of the PMI of skeletal remains. It is however clear that in a hypothetical flowchart those methods may be placed practically at the same level and a choice should always consider the evaluation of results by each technique, execution times and a costs/benefits relationship.     

Tissue levels of prostaglandins and what do they mean? Studies on the guinea-pig uterus

The ratios of the concentrations of PGF2 alpha, PGE2 and 6-keto-PGF1 alpha in guinea-pig uterine horns, which were removed and placed in ethanol in 1.5 to 2 min, were 0.3:1.0:0.6 on day 7 and 13.8:1.0:0.8 on day 15 of the oestrous cycle. Adding indomethacin (10 micrograms/ml) to the ethanol had no significant effect on the tissue levels observed. These ratios were similar to the ratios of the outputs of PGF2 alpha, PGE2 and 6-keto-PGF1 alpha from the guinea-pig uterus (0.6:1.0:0.9 on day 7 and 7.6:1.0:1.5 on day 15), but were different (particularly on day 7, but only for 6-keto-PGF1 alpha on day 15) to the ratios of the amounts of the three PGs synthesized by homogenates of the guinea-pig uterus (7.2:1.0:2.4 on day 7 and 11.7:1.0:3.3 on day 15). Consequently, the measurement of tissue levels of PGs in the guinea-pig uterus reflects PG synthesis by intact tissue and changes in this synthesis, rather than PG synthesis by homogenates (broken cell preparations). Therefore, it appears meaningful to measure levels of PGs in the guinea-pig uterus since they reflect uterine PG output. Separation of the endometrium from the myometrium, which involved handling and mild trauma, stimulated uterine PG levels, but the ratio of the levels of PGF2 alpha, PGE2 and 6-keto-PGF1 alpha in the endometrium was still similar to that found in the non-separated uterus.     

Are subordinates always stressed? A comparative analysis of rank differences in cortisol levels among primates

Among primate species there is pronounced variation in the relationship between social status and measures of stress physiology. An informal meta-analysis was designed to investigate the basis of this diversity across different primate societies. Species were included only if a substantial amount of published information was available regarding both social behavior and rank-related differences in stress physiology. Four Old World and three New World species met these criteria, including societies varying from small-group, singular cooperative breeders (common marmoset and cotton top tamarin) to large-troop, multi-male, multi-female polygynous mating systems (rhesus, cynomolgus, talapoin, squirrel monkeys, and olive baboon). A questionnaire was formulated to obtain information necessary to characterize the stress milieu for individuals in particular primate societies. We standardized cortisol values within each species by calculating the ratio of basal cortisol concentrations of subordinates to those of dominants in stable dominance hierarchies and expressing the ratio as a percentage (relative cortisol levels). The meta-analysis identified two variables that significantly predicted relative cortisol levels: subordinates exhibited higher relative cortisol levels when they (1). were subjected to higher rates of stressors, and (2). experienced decreased opportunities for social (including close kin) support. These findings have important implications for understanding the different physiological consequences of dominant and subordinate social status across primate societies and how social rank may differ in its behavioral and physiological manifestations among primate societies.     

Are monophyly and synapomorphy the same or different? Revisiting the role of morphology in phylogenetics

Species are groups of organisms, marked out by reproductive (replicative) properties. Monophyletic taxa are groups of species, marked out by synapomorphies. In Nelson’s analysis, monophyly and synapomorphy are identical relations. Monophyly and synapomorphy, however, are not equivalent relations. Monophyly is epistemically not accessible, whereas synapomorphy is epistemically accessible through character analysis. Monophyly originates with speciation, the two sister‐species that come into being through the splitting of the ancestral species lineage forming a monophyletic taxon at the lowest level of inclusiveness. Synapomorphy provides the empirical evidence for monophyly, inferred from character analysis in the context of a three‐taxon statement. If synapomorphy and monophyly were equivalent, phylogenetic systematists should find a single tree, instead of multiple equally parsimonious trees. Understanding synapomorphy as the relevant evidence for phylogenetic inference reveals a category mistake in contemporary phylogenetics: the treatment of morphological characters mapped onto molecular trees as synapomorphies and homoplasies. The mapping of morphological characters onto nodes of a molecular tree results in an empirically empty procedure for synapomorphy discovery. Morphological synapomorphies and homoplasies can only be discovered by morphological and combined analyses. The use of morphology in phylogenetic inference in general is defended by examples from Laurales and Squamata in particular. To make empirical evidence scientifically relevant in order to search for concordance, or dis‐concordance, of phylogenetic signal, is certainly more fruitful for phylogenetics than the uncritical mapping of morphological traits on a molecular scaffold. © The Willi Hennig Society 2010.     

Lab and field experiments: Are they the same animal?

To advance our understanding of biological processes we often plan our experiments based on published data. This can be confusing though, as data from experiments performed in a laboratory environment are sometimes different from, or completely opposite to, findings from similar experiments performed in the “real world”. In this mini-review, we discuss instances where results from laboratory experiments differ as a result of laboratory housing conditions, and where they differ from results gathered in the field environment. Experiments involving endocrinology and behavior appear to be particularly susceptible to influence from the environment in which they are performed.As such, we have attempted to promote discussion of the influence of housing environment on the reproductive axis, circadian biology and behavior, immune function, stress biology, neuroplasticity and photoperiodism. For example, why should a rodent species be diurnal in one housing environment yet nocturnal in another? Are data that are gathered from experiments in the laboratory applicable to the field environment, and vice-versa? We hope not only to highlight the need for experiments in both lab and field when looking at complex biological systems, but also to promote frank discussion of discordant data. Perhaps, just as study of individual variation has been gaining momentum in recent years, data from variation between experimental arenas can provide us with novel lines of research.     

Are dingoes a trophic regulator in arid Australia? A comparison of mammal communities on either side of the dingo fence

The direct and indirect interactions that large mammalian carnivores have with other species can have far‐reaching effects on ecosystems. In recent years there has been growing interest in the role that Australia's largest terrestrial predator, the dingo, may have in structuring ecosystems. In this study we investigate the effect of dingo exclusion on mammal communities, by comparing mammal assemblages where dingoes were present and absent. The study was replicated at three locations spanning 300 km in the Strzelecki Desert. We hypothesized that larger species of mammal subject to direct interactions with dingoes should increase in abundance in the absence of dingoes while smaller species subject to predation by mesopredators should decrease in abundance because of increased mesopredator impact. There were stark differences in mammal assemblages on either side of the dingo fence and the effect of dingoes appeared to scale with body size. Kangaroos and red foxes were more abundant in the absence of dingoes while Rabbits and the Dusky Hopping‐mouse Notomys fuscus were less abundant where dingoes were absent, suggesting that they may benefit from lower red fox numbers in the presence of dingoes. Feral cats and dunnarts (Sminthopsis spp.) did not respond to dingo exclusion. Our study provides evidence that dingoes do structure mammal communities in arid Australia; however, dingo exclusion is also associated with a suite of land use factors, including sheep grazing and kangaroo harvesting that may also be expected to influence kangaroo and red fox populations. Maintaining or restoring populations of dingoes may be useful strategies to mitigate the impacts of mesopredators and overgrazing by herbivores.     

Are the effects of different enrichment designs on the physiology and behaviour of DBA/2 mice consistent?

Environmental enrichment is intended to improve the well-being of laboratory animals. Although many researchers have indicated that environmental enrichment may enhance animal well-being, there is some evidence that enrichment differs in its effects on physiology and behaviour between species and strains. The present study focuses on the effects of different enrichment designs on the physiology and behaviour of male and female DBA/2 mice. A total of 48 DBA/2J mice, 24 males and 24 females were used for this experiment. Upon arrival at about 3 weeks of age, the animals were randomly allotted to three experimental groups: NE, non-enrichment; E1, enriched with nest box, wooden climbing bar and nest material according to Scharmann (1993); E2, enriched with horizontal and vertical dividers, modified from Haemisch and G?rtner (1994). Same-sex groups of four mice were housed for 12 weeks in type III Makrolon cages with (E1 or E2) or without (NE) enrichment objects. Behavioural performance (Open Field, Food Drive and Elevated Plus Maze tests) and physiological traits (haematological variables, body weight and organ weights, corticosterone and thyroxine levels) were measured. This study observed that enrichment had significant effects on the mean values of body weight (females), Open Field and Food Drive tests. The most significant housing differences were found between the E2 and NE/E1 groups. Furthermore, sex differences in the NE, E1 and E2 groups were not consistent for several variables (growth rate, relative weights of spleen, kidney and heart, Food Drive and Elevated Plus Maze behavioural performance). There was often a higher coefficient of variation (CV) in the E1 and E2 groups as compared to the NE group, chiefly in physiological traits and in the Open Field and Food Drive tests. The results of this study indicate, that the effects of enrichment designs used in the present study are not consistent, but vary according to sex and the variable studied.     

Allozymes and nDNA markers show different levels of population differentiation in the mussel Mytilus?edulis on British coasts

In order to test the hypothesis that natural selection can be operating on allozymes, six nuclear DNA markers were used to study population structure in six Mytilus edulis (Linnaeus, 1758) populations around the British Isles and the results compared with previous allozyme data from the same (two sites) or very close localities (the other four sites). Allozymes and nDNA markers show significant differentiation between populations at the P < 0.01 level, with the exception of the nDNA marker PLIIa. The results also indicate significant differences (modified version of the Lewontin–Krakauer test) between the two sets of markers which are about one order of magnitude higher for nDNA than for the allozyme loci. The bootstrap analysis was carried out to correct for the possibility that this difference is a sample size artefact. These results are consistent with the operation of balancing selection on allozymes or on loci in linkage disequilibrium with them. Handling editor: C. Sturmbauer     

Surface receptors: Are they involved in transformation of spermatozoa of Ascaris?

Exposure of the spheroidal spermatozoa of Ascaris suum to an extract of the male accessory gland causes their transformation into ameboid cells. We have investigated the mechanism of this transformation, also termed activation, by labeling the proteins of accessory gland extracts with fluorescein isothiocyanate (FITC) or [125I], followed by qualitative localization of the sperm activating substances (SAS) and quantitative measurements of [125I]-SAS binding. Fluorescent patches of FITC-conjugated SAS were localized at the spermatozoan surface and were concentrated primarily at the posterior region. Few fluorescent patches were detectable in the region of the newly formed pseudopodia following transformation. Although spermatozoan transformation occurs within 2-5 min after exposure to SAS, the fluorescent patches became more distinct after a minimum of 8 min and reached maximum density at 15-30 min. Spermatozoa activated with [125I]-SAS became radioactively labeled in direct proportion to the amount of available [125I]-SAS until a saturation level was reached. SDS-polyacrylamide gel electrophoresis combined with autoradiography indicated that the cells bind two SAS components, of small (9,000 MW) and large (56,000 MW) sizes. These same two components were also detectable in a membrane fraction, obtained by differential centrifugation, of the spermatozoa after incubation with [125I]-SAS. binding of the two SAS components was not inhibited by preincubation of the spermatozoa with trypsin or Concanavalin A; however, the 56,000 MW component of SAS was not detectable in autoradiograms of spermatozoa incubated with periodic acid (1.6-10 mM) treated SAS. Such cells also failed to transform into ameboid spermatozoa. These results indicate that the two components of SAS that bind to the spermatozoan surface are possibly responsible for inducing the cell transformations associated with activation.     

Nucleic acids in circulation: Are they harmful to the host?

It has been estimated that 10(11) -10(12) cells, primarily of haematogenous origin, die in the adult human body daily, and a similar number is regenerated to maintain homeostasis. Despite the presence of an efficient scavenging system for dead cells, considerable amounts of fragmented genetic material enter the circulation in healthy individuals. Elevated blood levels of extracellular nucleic acids have been reported in various disease conditions; such as ageing and age-related degenerative disorders, cancer; acute and chronic inflammatory conditions, severe trauma and autoimmune disorders. In addition to genomic DNA and nucleosomes, mitochondrial DNA is also found in circulation, as are RNA and microRNA. There is extensive literature that suggests that extraneously added nucleic acids have biological actions. They can enter into cells in vitro and in vivo and induce genetic transformation and cellular and chromosomal damage; and experimentally added nucleic acids are capable of activating both innate and adaptive immune systems and inducing a sterile inflammatory response. The possibility as to whether circulating nucleic acids may, likewise, have biological activities has not been explored. In this review we raise the question as to whether circulating nucleic acids may have damaging effects on the host and be implicated in ageing and diverse acute and chronic human pathologies.     

A comparison of the photosynthesis — light intensity relationship in phylogenetically different marine microalgae

Measured under equivalent physiological conditions, the photosynthesis-light intensity relationship based on oxygen production/mg chlorophyll a was found to be the same in five species representing the different chlorophyll c containing divisions of marine phytoplankton. Other non-photochemical metabolic processes related to photosynthesis such as diurnal variations, maximal photosynthesis rates, and dark oxygen uptake were quite different, and so these are the more significant factors in production and ecological distribution of diatoms, dinoflagellates, and coccolithophores. In contrast, the green algae tested showed a significantly different photosynthesis-light intensity curve from the chlorophyll c group.     

Effects of different nitrogen:phosphorus levels on the growth and ecological stoichiometry of Glycyrrhiza uralensis北大核心CSCD

Aims The increase in atmospheric nitrogen (N) deposition has accelerated N cycling of ecosystems, probably resulting in increases in phosphorus (P) demand of ecosystems. Studies on the effects of artificial N:P treatment on the growth and carbon (C), N, P ecological stoichiometry of desert steppe species could provide not only a new insight into the forecasting of how the interaction between soils and plants responses to long-term atmospheric N deposition increase, but also a scientific guidance for sustainable management of grassland in northern China under global climate change. Methods Based on a pot-cultured experiment conducted for Glycyrrhiza uralensis (an N-fixing species) during 2013 to 2014, we studied the effects of different N:P supply ratios (all pots were treated with the same amount of N but with different amounts of P) on aboveground biomass, root biomass, root/shoot ratio, and C:N:P ecological stoichiometry both in G. uralensis (leaves and roots) and in soils. Additionally, through the correlation analyses between biomass and C:N:P ecological stoichiometry in leaves, roots, and soils, we compared the differences among the C:N:P ecological stoichiometry of the three pools, and discussed the indication of C:N:P ecological stoichiometry in soils for the growth and nutrient uptake of G. uralensis. Important findings The results showed that, reducing N:P decreased C:P and N:P ratios both in G. uralensis (leaves and roots) and in soils but increased aboveground biomass and root biomass of G. uralensis, indicating that low to moderate P addition increased P availability of soils and P uptake of G. uralensis. However, excessive low N:P (high P addition) led to great decreases in soil C:P and N:P ratios, thus hindering N uptake and the growth of G. uralensis. C:N:P ratios in the two pools of G. uralensis (especially in leaves) had close correlations with soil C:N:P ratio, indicating that the change in soil C:N:P ratio would have a direct influence on plants. Our results suggest that, through regulating C:N:P ratio in leaves and soils, appropriate amounts of P addition could balance soil P supply and plant P demand and compensate the opposite influences of long-term atmospheric N deposition increase on the structure of desert steppe.