Longleaf pine cone–radial growth relationships in the southeastern U.S.A.

Longleaf pine (Pinus palustris Mill.) cones have been counted annually by the United States Forest Service (USFS) at eleven locations throughout the species’ range since 1958. These data have been useful for understanding spatiotemporal patterns in longleaf pine cone production, and are beneficial in timing regeneration efforts. Variations in annual mast (i.e. seed crop) are known to influence ring widths in numerous tree species, yet this relationship is poorly understood for longleaf pine. This research examines the relationship between longleaf pine cone data and tree-ring growth from trees sampled in the multi-decadal USFS cone-crop study. We examined cone–radial growth relationships using individual tree-ring data and proprietary cone data for each tree from six sites in four locations in the southeastern USA. We found that longleaf pine cones were correlated with basal area increment growth (BAI) over the three-year cone-development cycle. Low BAI years were more frequently associated with above-average cone crop and BAI during years that coincided with the largest cone-crop class (bumper, > 100 cones per tree) were statistically less than any other cone class. We prepared linear models that predicted radial growth using PDSI and cones as predictors, and found that including cones in the models did not improve adjusted R² values. We conclude that while cone production is inversely related to radial growth, the combination of infrequent bumper years and the concentration of cone production by a few trees per stand, creates an environment where radial-growth chronologies assembled from longleaf pine for dendroclimatic purposes are unlikely to be significantly influenced by reproductive strain.     

Settlement and mortality of the Christian site (1050 A.D.–1300 A.D.) of Meinarti (Sudan)

Demographic analysis of cemetery data can be a useful complement to archaeological studies. Skeletal remains, when they comprise a representative sample, can serve to define certain relationships between the cultural and biological aspects of human adaptation. Furthermore, differential mortuary practices often mirror the status system of a society.Specifically, this paper examines the status system and mortality pattern of the community of Meinarti in the Sudan. Stationary life table analysis shows age, sex, and an additional factor (reflected in survival) as determinants of status. In addition, the analysis of mortality supports Adam's hypothesis of village growth and decline.     

Microchips in the laboratory of A.D. Mirzabekov: 1988–2007

The paper reviews the last period in the research work of A.D. Mirzabekov, when gel-based biochips were invented, studied, and introduced in practice. This work, starting from the early stages of the Human Genome Project up to the recent development of diagnostic and protein biochips, is considered in the context of the worldwide development of microarray technologies.     

A global analysis of avian island diversity–area relationships in the Anthropocene

Research on island species–area relationships (ISAR) has expanded to incorporate functional (IFDAR) and phylogenetic (IPDAR) diversity. However, relative to the ISAR, we know little about IFDARs and IPDARs, and lack synthetic global analyses of variation in form of these three categories of island diversity–area relationship (IDAR). Here, we undertake the first comparative evaluation of IDARs at the global scale using 51 avian archipelagic data sets representing true and habitat islands. Using null models, we explore how richness-corrected functional and phylogenetic diversity scale with island area. We also provide the largest global assessment of the impacts of species introductions and extinctions on the IDAR. Results show that increasing richness with area is the primary driver of the (non-richness corrected) IPDAR and IFDAR for many data sets. However, for several archipelagos, richness-corrected functional and phylogenetic diversity changes linearly with island area, suggesting that the dominant community assembly processes shift along the island area gradient. We also find that archipelagos with the steepest ISARs exhibit the biggest differences in slope between IDARs, indicating increased functional and phylogenetic redundancy on larger islands in these archipelagos. In several cases introduced species seem to have ‘re-calibrated’ the IDARs such that they resemble the historic period prior to recent extinctions.     

Diversity of fish species in the trawl catches in the southeastern Barents Sea in 1980–2008

Analysis of trawl catches in the southeastern Barents Sea was performed for the period of 1980–2008. One lamprey and 48 fish species were defined, including 38 marine fish species, 8 anadromous and amphidromous species, and 1 freshwater species. The ichthyofauna of several areas of the southeastern Barents Sea was described (Cheshskaya Inlet, Pomorskiy Strait, southeastern Pechora Sea, Pechora Sea, Khaipudyrskaya Inlet and adjacent areas). Biodiversity indexes and Shannon Index were applied to describe the species diversity. Cluster analysis was applied to compare the species lists from different areas. Multiyear dynamics of ichthyofauna was studied. The tendency of geographical range expansion eastward was observed for boreal species.     

50 Years after the Death of D.A. Sabinin (1889–1951)

Russian Journal of Plant Physiology -     

Variation in the methods leads to variation in the interpretation of biodiversity–ecosystem multifunctionality relationships

生物多样性常常和生态系统多功能性(生态系统同时提供多个生态系统功能的能力)正相关。然而,生物多样性与生态系统多功能性的关系是否依赖于生态系统功能的数目有诸多争议。其中,生物多样性对生态系统多功能性的影响或许不随生态系统功能数目的变化而变化,或者随生态系统功能数目的增多而增强。我们期望通过研究不同生态系统多功能性指数的统计原理来解决这些争议。 我们使用了模型模拟和一系列来自不同空间尺度(从局域到全球)和不同生物群系(温带和高寒草地、森林和干旱地)的经验数据。我们回顾了量化生态系统多功能性的三种方法,包括平均值法、加和法和阈值法。我们发现随着生态系统功能数目的增加,生物多样性与生态系统多功能性的关系要么不变,要么增强。这些结果可由平均和加和的多功能性指数的统计原理来解释。具体来讲,当利用生态系统功能的平均值计算多功能性指数时,由于多样性对多功能性的效应等于多样性对单个生态系统功能效应的平均值,所以不会随生态系统功能数目的变化而变化。同样的道理,当利用单个生态系统的加和值计算多功能性指数时,多样性的效应会随着生态系统功能数目的增加而增强。我们提出了一个改进的多功能性指数,将平均或加和多功能性指数转化为标准化的多功能性指数, 以便于对不同研究的结果进行比较。此外,我们提出了基于变量数值范围的标准化方法来解决阈值法的数学假象问题(多样性效应随生态系统功能数目的增加而增强)。我们的研究结果表明,量化多功能性指数的方法不同,结果也不同。因此,有必要加深对不同方法数理基础的理解。而标准化的多功能性指数为比较不同研究中的生物多样性与生态系统多功能性的关系提供了有效的方法。     

Induction of N–malonyl–D–tryptophan by drought stress. Is D–tryptophan the only D–amino acid appeared in wilted leaves?

D-amino acid were searched in wilted tomato leaves. D-Isomers of free amino acids were not revealed by the treatment with L- and D-amino acid oxidases. The noncationic fraction of the extract contained N-malonyl-D-tryptophan and no other N-acylated amino acids. A special search for endogenous N-malonyl-D-phenylalanine gave negative results. Exogenous¹⁴C-malonate was only incorporated in one Chromatographic zone corresponding to N-malonyl-D-tryptophan. It is concluded that drought stress does not induce the appearance of D-amino acids except for D-tryptophan which is accumulated in the malonylated form.     

Comparison of the Higher-Severity Fire Regime in Historical (A.D. 1800s) and Modern (A.D. 1984–2009) Montane Forests Across 624,156?ha of the Colorado Front Range

There are concerns that recent fires, following a century of land uses, are burning in dry western forests in an uncharacteristic manner with large patches of higher-severity fire affecting long-term ecosystem dynamics. For example, it is well documented that a mixed-severity fire regime predominated over montane forests of the Colorado Front Range. However, much about the historical fire regime is unknown including the size, frequency, and distribution of higher-severity fires. We addressed these questions utilizing data from the original land surveyors who recorded locations of burned timber along survey lines resulting in a coarse-scale transect of fire occurrence across 624,156?ha. We reconstructed higher-severity burn patches, size distribution, and fire rotation for the 1800s (A.D. 1809–1883) and compared to the characteristics of modern fires over a recent 26-year period (A.D. 1984–2009) taken from remotely sensed data. We found the historical geometric mean higher-severity patch was 170.9?ha and the maximum patch size was 8,331?ha; the higher-severity fire rotation was 248.7?years. In addition, we confirmed that higher-severity fires were historically less common at elevations below 2,200?m. Modern fires had a geometric mean patch size of 90.0?ha (patches >20?ha) and a maximum size of 5,183?ha; the higher-severity fire rotation was 431?years. The distributions of higher-severity patches were only 63.5% similar, as the historical distribution had fewer small patches and more large patches. The mixed-severity fire regime, historically, included a significant portion of higher-severity fire and large burn patches; modern fires appear to be within the range of historical variability.     

A J E Smith,M.A., D.Phil., D.Sc. (1935–2012)

Abstract

Based on morphology and phylogenetical analyses of nrITS sequences, the Andean endemic Plagiochila (Jamesoniella) dependula is placed in Plagiochila sect. Fuscoluteae. Perianths, oil bodies and sporophytes are described for the first time. Morphologically, P. dependula is characterized by entire, dorsally mostly shortly decurrent, laterally appressed, reniform leaves which are covered by irregular papillae and membranous wax platelets, papillose oil bodies, intercalary androecia with opposite bracts that overlap dorsally, a plagiochilid perianth with an entire mouth, a 250 μm thick capsule wall with thickenings in all layers, large 1–4 celled spores, and bispiral elaters. Morphotypes of Plagiochila fuscolutea with laterally appressed leaves differ from P. dependula by an at least moderately decurrent, broad dorsal leaf base, a ±smooth upper leaf surface, and by its often toothed leaf apices. Plagiochila wolframii is placed in the synonymy of P. fuscolutea. Maximum likelihood and parsimony analyses of 29 Plagiochila ITS sequences resolve P. dependula in a well-supported clade with several other representatives of P. sect. Fuscoluteae. Branch lengths within sect. Fuscoluteae point to a sudden diversification. Accessions of P. heterophylla s.str. from Great Britain (formerly known as P. atlantica) and Costa Rica form an unsupported monophyletic lineage.     

pH-dependence and structure–activity relationships in the papain-catalysed hydrolysis of anilides

The pH-dependence of the Michaelis-Menten parameters for the papain-catalysed hydrolysis of N-acetyl-l-phenylalanylglycine p-nitroanilide was determined. The equilibrium binding constant, K(s), is independent of pH between 3.7 and 9.3, whereas the acylation constant, k(+2), shows bell-shaped pH-dependence with apparent pK(a) values of 4.2 and 8.2. The effect of substituents in the leaving group on the acylation constant of the papain-catalysed hydrolysis of hippuryl anilides and N-acetyl-l-phenylalanylglycine anilides gives rise in both series to a Hammett rho value of -1.04. This indicates that the enzyme provides electrophilic, probably general-acid, catalysis, as well as the nucleophilic or general-base catalysis previously found. A mechanism involving a tetrahedral intermediate whose formation is general-base-catalysed and whose breakdown is general-acid-catalysed seems most likely. The similarity of the Hammett rho values appears to exclude facilitated proton transfer as a means through which the specificity of papain is expressed.     

Untangling structure–function relationships in the rhomboid family of intramembrane proteases

Rhomboid proteases are a family of integral membrane proteins that have been implicated in critical regulatory roles in a wide array of cellular processes and signaling events. The determination of crystal structures of the prokaryotic rhomboid GlpG from Escherichia coli and Haemophilus influenzae has ushered in an era of unprecedented understanding into molecular aspects of intramembrane proteolysis by this fascinating class of protein. A combination of structural studies by X-ray crystallography, and biophysical and spectroscopic analyses, combined with traditional enzymatic and functional analysis has revealed fundamental aspects of rhomboid structure, substrate recognition and the catalytic mechanism. This review summarizes these remarkable advances by examining evidence for the proposed catalytic mechanism derived from inhibitor co-crystal structures, conflicting models of rhomboid-substrate interaction, and recent work on the structure and function of rhomboid cytosolic domains. In addition to exploring progress on aspects of rhomboid structure, areas for future research and unaddressed questions are emphasized and highlighted. This article is part of a Special Issue entitled: Intramembrane Proteases.     

Tree rings reveal a growth-decline event in A.D. 1875–1883 in a Tibetan plateau juniper forest

Forest declines under global warming have received much attention in studies of forest ecology, yet such events in periods before climate warming have been less studied because of shortage in documentation of past decline events. Here we used dendroecological techniques to identify forest decline events in the past five and a half centuries for a juniper forest near Lhasa of Tibet, China. Data of tree ring-widths were obtained from 42 relatively old trees after sample collection, measurement and crossdating. Radial growth of these trees was significantly and positively correlated with total precipitation in May and June. Persistent and severe growth reductions, lasting for at least eight years, were identified for each sample. We found that greater than 35% of the trees exhibited persistent and severe growth reductions in the interval A.D. 1875–1883, suggesting a growth decline event in the forest. This growth decline was the most severe event in the past five and half centuries. The weakened Indian monsoon in A.D. 1875–1878, which would result in extreme and prolonged droughts at spatially large scale in the monsoon zone, was most likely the driving force for the forest decline event discovered in this study. Our results suggested that future risk of juniper forest declines in central Tibetan plateau will be related to extreme droughts which could be amplified by warming. The study highlighted the importance of examining growth trajectory of individual trees in assessing forest health in a long perspective.     

Evaluation of the importance of roe deer fawns in the spring–summer diet of red foxes in southeastern Norway

Red fox Vulpes vulpes predation on roe deer Capreolus capreolus fawns has the potential to strongly affect prey population dynamics, but it is unclear whether this relationship is symmetrical or not. We analysed the spring–summer diet of adult foxes and of their cubs in a fragmented agricultural area of southeastern Norway, where a parallel study showed that the predator kills annually 25% of the radio-monitored roe deer fawns. The overall diet was highly varied and was dominated by small mammals (33% volume), especially Microtus agrestis, and medium-large mammals (25%), largely represented by fawns. The frequency of occurrence (FO) of fawns in the diet of adult foxes was highest in early spring, thus, supporting previous studies showing that the predator started actively hunting for fawns from the very beginning of the birth season. During the summer, the FO of both fawns and small mammals markedly declined, while that of berries and invertebrates increased. As expected for central-place foragers, cubs consumed a higher proportion of large prey items compared to adults. In particular, 25% of scats from cubs—versus 9% from adults—contained roe deer remains, suggesting a high profitability of fawns for vixens raising offspring. However, considering the wide food spectrum and the availability of several large prey items in our study area, it seems unlikely that the importance of fawns to the diet and population dynamics of red foxes could be as great as the impact of the predator on roe deer populations. This asymmetrical relationship implies that there are unlikely to be any stabilising feedback mechanisms in the predator–prey relationship.     

Ximaosteroids A–D,new steroids from the Hainan soft coral Scleronephthya sp.

One novel uncommon steroid, ximaosteroid A (1), possessing an unusual tetrahydrofuran moiety and three new pregnane steroids, ximaosteroids B–D (2–4), were isolated from the Hainan soft coral Scleronephthya sp. Their structures were elucidated on the basis of detailed spectroscopic (IR, MS, and 2D NMR) analysis and by comparison with those reported in the literature.     

A preliminary fish assemblage index for a transitional river–reservoir system in southeastern Brazil

Large river–reservoir systems are some of the most difficult aquatic ecosystems to assess because: (1) they typically lack minimally disturbed reference sites; (2) the reservoirs are not natural systems to begin with; and (3) reservoirs with high exchange rates are transitional systems between rivers and lakes. These features are further complicated in Brazil where fish species taxonomy is incomplete (let alone fully described ecologically), where waters naturally have high organic and thermal loadings, and where dams and reservoirs provide most of the nation's electricity and water supplies. As a first step towards generating a biological tool for assessing the effects of reservoirs on rivers, we developed a preliminary River–Reservoir Fish Assemblage Index (RRFAI) in a transitional river–reservoir system in southeastern Brazil. To do so, we gill-netted fish monthly between October 2006 and September 2007 (excluding May and July 2007) immediately upriver of the reservoir, in the upper reservoir, in the lower reservoir, and immediately downriver of the reservoir. In developing our RRFAI we sought fish assemblage metrics to represent ecological characteristics including richness, habitat, trophic, tolerance, and resilience guilds. Despite clear differences in fish assemblage composition between river and reservoir sites, we found 9 metrics common to both systems that were nonredundant and had low sampling variability (number of native species, number of characiform species, number of siluriform species, % omnivorous individuals, % invertivorous individuals, % non-native carnivorous individuals, % intolerant individuals, % tolerant individuals, number of tolerant species). Fish assemblage condition was significantly and consistently lower in the lower reservoir. There was no significant difference between the dry and wet season in RRFAI scores, suggesting that a single season sample should usually suffice. Further research is needed along distinct disturbance gradients in multiple river–reservoir systems in Brazil to confirm the sensitivity of our preliminary RRFAI for assessing the physical and chemical habitat disturbances common to such systems.     

Isometric torque–angle relationships of the elbow flexors and extensors in the transverse plane

Maximal voluntary isometric torque–angle relationships of elbow extensors and flexors in the transverse plane (humerus elevation angle of 90°) were measured at two different horizontal adduction angles of the humerus compared to thorax: 20° and 45°. For both elbow flexors and extensors, the torque–angle relationship was insensitive to this 25° horizontal adduction of the humerus. The peak in torque–angle relationship of elbow extensors was found at 55° (0° is full extension). This is closer to full elbow extension than reported by researchers who investigated this relationship in the sagittal plane. Using actual elbow angles during contraction, as we did in this study, instead of angles set by the dynamometer, as others have done, can partly explain this difference.We also measured electromyographic activity of the biceps and triceps muscles with pairs of surface electrodes and found that electromyographic activity level of the agonistic muscles was correlated to measured net torque (elbow flexion torque: Pearson’s r = 0.21 and extension torque: Pearson’s r = 0.53). We conclude that the isometric torque–angle relationship of the elbow extensors found in this study provides a good representation of the force–length relationship and the moment arm–angle relationship of the elbow extensors, but angle dependency of neural input gives an overestimation of the steepness.