An accident at work? Traumatic lesions in the skeleton of a 4th millennium BCE “wagon driver” from Sharakhalsun,Russia

The study of ante-mortem trauma is a popular and important aspect of palaeopathological analysis. The majority of publications focus on a particular assemblage, skeletal element or type of fracture, with case studies of single individuals with multiple/unusual traumata being much rarer in the literature. This paper presents the case of an adult male from the Bronze Age site of Sharakhalsun, Russia, buried, uniquely, in a sitting position on a fully assembled wagon, who displayed evidence for multiple healed ante-mortem fractures of the cranium, axial and appendicular skeleton. The mechanisms and likely etiologies of the fractures are presented, with reference to modern and 19th century clinical literature, and possible interpretations suggested: that the individual was involved in a severe accident involving a wagon or draft animals, or both, a number of years before his death. The suggestion is also made that the unique burial position of the individual was a form of commemoration by the community of the survival and recovery of the individual from such a serious incident.     

Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa

BIOME 6000 is an international project to map vegetation globally at mid‐Holocene (6000 ¹⁴C yr bp ) and last glacial maximum (LGM, 18,000 ¹⁴C yr bp ), with a view to evaluating coupled climate‐biosphere model results. Primary palaeoecological data are assigned to biomes using an explicit algorithm based on plant functional types. This paper introduces the second Special Feature on BIOME 6000. Site‐based global biome maps are shown with data from North America, Eurasia (except South and Southeast Asia) and Africa at both time periods. A map based on surface samples shows the method’s skill in reconstructing present‐day biomes. Cold and dry conditions at LGM favoured extensive tundra and steppe. These biomes intergraded in northern Eurasia. Northern hemisphere forest biomes were displaced southward. Boreal evergreen forests (taiga) and temperate deciduous forests were fragmented, while European and East Asian steppes were greatly extended. Tropical moist forests (i.e. tropical rain forest and tropical seasonal forest) in Africa were reduced. In south‐western North America, desert and steppe were replaced by open conifer woodland, opposite to the general arid trend but consistent with modelled southward displacement of the jet stream. The Arctic forest limit was shifted slighly north at 6000 ¹⁴C yr bp in some sectors, but not in all. Northern temperate forest zones were generally shifted greater distances north. Warmer winters as well as summers in several regions are required to explain these shifts. Temperate deciduous forests in Europe were greatly extended, into the Mediterranean region as well as to the north. Steppe encroached on forest biomes in interior North America, but not in central Asia. Enhanced monsoons extended forest biomes in China inland and Sahelian vegetation into the Sahara while the African tropical rain forest was also reduced, consistent with a modelled northward shift of the ITCZ and a more seasonal climate in the equatorial zone. Palaeobiome maps show the outcome of separate, independent migrations of plant taxa in response to climate change. The average composition of biomes at LGM was often markedly different from today. Refugia for the temperate deciduous and tropical rain forest biomes may have existed offshore at LGM, but their characteristic taxa also persisted as components of other biomes. Examples include temperate deciduous trees that survived in cool mixed forest in eastern Europe, and tropical evergreen trees that survived in tropical seasonal forest in Africa. The sequence of biome shifts during a glacial‐interglacial cycle may help account for some disjunct distributions of plant taxa. For example, the now‐arid Saharan mountains may have linked Mediterranean and African tropical montane floras during enhanced monsoon regimes. Major changes in physical land‐surface conditions, shown by the palaeobiome data, have implications for the global climate. The data can be used directly to evaluate the output of coupled atmosphere‐biosphere models. The data could also be objectively generalized to yield realistic gridded land‐surface maps, for use in sensitivity experiments with atmospheric models. Recent analyses of vegetation‐climate feedbacks have focused on the hypothesized positive feedback effects of climate‐induced vegetation changes in the Sahara/Sahel region and the Arctic during the mid‐Holocene. However, a far wider spectrum of interactions potentially exists and could be investigated, using these data, both for 6000 ¹⁴C yr bp and for the LGM.     

Late Pleistocene environmental changes lead to unstable demography and population divergence of Anopheles albimanus in the northern Neotropics

We investigated the historical demography of Anopheles albimanus using mosquitoes from five countries and three different DNA regions, the mitochondrial cytochrome oxidase subunit I gene (COI), the single copy nuclear white gene and the ribosomal internal transcribed spacer two (ITS2). All the molecular markers supported the taxonomic status of a single species of An. albimanus. Furthermore, agreement between the COI and the white genes suggested a scenario of Pleistocene geographic fragmentation (i.e., population contraction) and subsequent range expansion across southern Central America.     

Morpho-anatomical responses ofTrigonella foenum graecum Linn. to induced cadmium and lead stress

Effect of different concentrations of cadmium (0, 5,15, 30, 50 μg/g of soil) and lead (0,25, 50,100,200 μg/g of soil) on morphological and anatomical features ofTrigonella foenum graecum Linn, was studied at pre-flowering, flowering and post flowering stages. Morphological attributes, like number of leaves per plant, total leaf area of the plant and single leaf area, dry mass of stem, root and leaf, length of shoot, root and plant, size of stomata and stomatal pore, and the density of stomata on both epidermises were significantly reduced under metal stress at all the developmental stages. Trichome length on both epidermises increased while their density decreased under metal stress. Under cadmium stress, proportion of pith and vasculature decreased but cortex increased in the stem. Under lead stress, proportion of pith and vasculature increased but cortex decreased in the stem. In the root, proportion of vasculature and pith increased and cortex decreased in response to both cadmium and lead stresses. Dimensions of vessel element and xylem fibre in the wood of stem and root decreased under the cadmium and lead stresses. Decrease in density of vessel element in the stem and root with advancement of age was more pronounced in plants grown under cadmium and lead stresses.     

Protein and enzyme levels during development in a high lysine barley mutant

Dry weight, protein, total free amino acids, levels of nitrogen assimilation, enzymes GDH, GOT and glutamate synthase, hydrolytic enzymes protease and amylase, peroxidase and nitrate reductase have been studied in high lysine barley mutant Notch-2 and its parents, NP 113 grains, during development. Dry weight and protein per grain was higher in NP 113 throughout development. The decrease in protein in Notch-2 mutant is neither due to limitation of amino acids nor to any of the key nitrogen assimilating enzymes as evident from the higher level of free amino acids, nitrate reductase and comparable levels of GDH, GOT and glutamate synthase in it as compared to its parent NP 113. During later stages of development, protease level between NP 113 and Notch-2 was nearly the same. Notch-2 had a lower level of amylase activity per grain. Peroxidase activity was higher in Notch-2 than NP 113 at and after the 17 day stage.     

Effects of mercuric ion on the conformation and activity of Penaeus Vannamei beta-N-acetyl-d-glucosaminidase

beta-N-acetyl-d-glucosaminidase (NAGase, EC.3.2.1.52), a composition of the chitinases, catalyzes the cleavage of N-acetylglucosamine polymers into N-acetylglucosamine. In this paper, the effects of mercuric ion on the activity of NAGase from Penaeus vannamei for the hydrolysis of pNP-NAG have been studied. The results show that HgCl2 can lead to irreversible inactivation to this enzyme. The inactivation process follows a first-order reaction and the inactivation rate constants have been determined. The relationship between the inactivation rate constants and HgCl2 concentration has been studied and the result shows that only one molecule of HgCl2 binds to the enzyme molecule to lead the enzyme lose its activity. Moreover, the conformational changes of the enzyme inactivated by HgCl2 were studied by following changes in the intrinsic fluorescence emission and ultraviolet absorption spectra.     

Effect of Oxygen on Temporary Stabilization of Photoreduced Quinone Acceptors in Rhodobacter sphaeroides Reaction Centers

The effect of molecular oxygen on the photochemical activity of the Rhodobacter sphaeroides reaction centers frozen to 160 K under actinic illumination was investigated by the ESR method. About 90% of initially photochemically active bacteriochlorophyll (P) were fixed at 160 K for a long time in aerobic samples in an inactive form. In anaerobic samples, not more than 65% were fixed in an inactive form under the same conditions. In aerobic preparations, a small portion of photochemically active bacteriochlorophyll (about 10%) that retains its photochemical activity at 160 K after freezing under illumination has dark reduction kinetics similar to that of samples at room temperature after several seconds of actinic illumination. In anaerobic samples frozen under illumination, the remaining photochemically active reaction centers (35%) have the same dark reduction kinetics as samples illuminated at 295 K for 1-2 min. The conclusion is that the irreversible stabilization of bacteriochlorophyll P in the oxidized inactive state formed in the reaction centers frozen under illumination is brought about by light-induced conformational changes fixed under low temperatures.     

Comparison of ligand-induced conformational changes and domain closure mechanisms, between prokaryotic and eukaryotic dehydroquinate synthases

Dehydroquinate synthase (DHQS) is a potential target for the development of novel broad-spectrum antimicrobial drugs, active against both prokaryotes and lower eukaryotes. Structures have been reported for Aspergillus nidulans DHQS (AnDHQS) in complexes with a range of ligands. Analysis of these AnDHQS structures showed that a large-scale domain movement occurs during the normal catalytic cycle, with a complex series of structural elements propagating substrate binding-induced conformational changes away from the active site to distal locations. Compared to corresponding fungal enzymes, DHQS from bacterial species are both mono-functional and significantly smaller. We have therefore determined the structure of Staphylococcus aureus DHQS (SaDHQS) in five liganded states, allowing comparison of ligand-induced conformational changes and mechanisms of domain closure between fungal and bacterial enzymes. This comparative analysis shows that substrate binding initiates a large-scale domain closure in both species' DHQS and that the active site stereochemistry, of the catalytically competent closed-form enzyme thus produced, is also highly conserved. However, comparison of AnDHQS and SaDHQS open-form structures, and analysis of the putative dynamic processes by which the transition to the closed-form states are made, shows a far lower degree of similarity, indicating a significant structural divergence. As a result, both the nature of the propagation of conformational change and the mechanical systems involved in this propagation are quite different between the DHQSs from the two species.     

Functional independence of a peptide with the sequence of human apolipoprotein A-I central region

Previous results [J. Biol. Chem. 276 (2001) 16978] indicated that an apolipoprotein A-I (apoAI) central region swings away from lipid contact in discoidal high density lipoproteins (HDL), but it is able to penetrate into the bilayer of lipid vesicles. In this work, we have studied the interaction with lipid membranes of a synthetic peptide with the sequence of apoAI region between residues 77 and 120 (AI 77-120). Like apoAI, AI 77-120 binds to phospholipid vesicles and shows selectivity for cholesterol-containing membranes. Moreover, AI 77-120 promotes cholesterol desorption from membranes in a similar fashion as apoAI and can stimulate cholesterol efflux from Chinese hamster ovary cells. AI 77-120 has a considerable alpha-helical content in water solution, and its secondary structure is not largely modified after binding to membranes. Both apoA-I and AI 77-120 are oligomeric in the lipid-bound state, suggesting that dimerization of the central domain could be required for the membrane binding activity of apoA-I in HDL.     

Rational behavioral response and the transmission of STDs

The susceptible-infected (SI) model is extended by allowing for individual optimal choices of self-protective actions against infection, where agents differ with respect to preferences and costs of self-protection. It is shown that a unique endemic equilibrium prevalence exists when the basic reproductive number of a STD is strictly greater than unity, and that the disease-free equilibrium is the unique steady state equilibrium when the basic reproductive number is less than or equal to one. Unlike in models that take individual behavior as given and fixed, the endemic equilibrium prevalence need not vary monotonically with respect to the basic reproductive number. Specifically, with endogenously determined self-protective behavior, a reduction in the basic reproductive number may in fact increase the endemic equilibrium prevalence. The global stability of the endemic steady state is established for the case of a homogeneous population by showing that, for any non-zero initial disease prevalence, there exists an equilibrium path which converges to the endemic steady state.