Modelling environmental variation in Young's modulus for Pinus radiata and implications for determination of critical buckling height

• Background and Aims Although density-specific stiffness,E/, (where E is Young's modulus and is wood density) is oftenassumed constant by the elastic similarity model, and in determinationof critical buckling height (H_crit), few studies have testedthis assumption within species. Here this assumption is testedfor Pinus radiata growing across an environmental gradient,and theory is combined with data to develop a model of Young'smodulus. • Methods Analyses use an extensive series of environmentalplots covering the range of climatic and edaphic conditionsover which P. radiata is grown in New Zealand. Reduced majoraxis regression was used to determine scaling exponents betweenlog–log plots of H_crit vs. groundline diameter (D), andE/ vs. D. Path analysis was used to identify significant directand indirect (through stem slenderness) edaphic and climaticinfluences on E. • Key Results Density-specific stiffness exhibited 3-foldvariation. As E/ scaled positively with D, the exponent of 0·95between H_crit and D exceeded the assumed value of 0·67under constant E/. The final path analysis model included meanair temperature in early autumn (T_aut) and slenderness as significant(P < 0·05) positive direct influences on E. Tree leafarea index and T_aut were indirectly associated with E throughtheir significant (P < 0·05) positive direct relationshipwith stem slenderness. Young's modulus was most sensitive toT_aut, followed by stem slenderness then leaf area index, andthe final model explained 76 % of the variance in E. • Conclusions The findings suggest that within speciesE/ variation may influence H_crit and the scaling exponent betweenD and H_crit so important in assumptions regarding allometricrelationships. The model presented may provide a useful meansof determining variation in E, E/ and H_crit across environmentalgradients.     

Variations in response to induced stem bending in seedlings of Pinus radiata

Summary The occurrence of stem deformation in Pinus radiata plantations has been examined previously in terms of the factors leading to the onset of bending symptoms. In this study the influence of seedling family and nitrogen availability on the ability of seedlings to recover from deformation was investigated under glasshouse conditions. Seedlings from four families ranging from resistant to susceptible to stem deformation were used. Stem deformation was induced by loading stems with a known weight and comparing bending moments and rates of recovery. Significant differences between families were found with more susceptible families exhibiting greater initial magnitudes of stem lean. Similarly these families also exhibited greater rates of apical elongation following bending despite the larger stem leans. This resulted in more exaggerated stem bends as a consequence of the recovery of the lower stem pushing the upper stem away from the vertical. The strength characteristics of the stems could not explain differences between families. Susceptibility to stem deformation was explained more by stem slenderness expressed as stem height to root collar diameter.     

A functional-structural model for radiata pine (Pinus radiata) focusing on tree architecture and wood quality

Backgrounds and Aims

Functional–structural models are interesting tools to relate environmental and management conditions with forest growth. Their three-dimensional images can reveal important characteristics of wood used for industrial products. Like virtual laboratories, they can be used to evaluate relationships among species, sites and management, and to support silvicultural design and decision processes. Our aim was to develop a functional–structural model for radiata pine (Pinus radiata) given its economic importance in many countries.

Methods

The plant model uses the L-system language. The structure of the model is based on operational units, which obey particular rules, and execute photosynthesis, respiration and morphogenesis, according to their particular characteristics. Plant allometry is adhered to so that harmonic growth and plant development are achieved. Environmental signals for morphogenesis are used. Dynamic turnover guides the normal evolution of the tree. Monthly steps allow for detailed information of wood characteristics. The model is independent of traditional forest inventory relationships and is conceived as a mechanistic model. For model parameterization, three databases which generated new information relating to P. radiata were analysed and incorporated.

Key Results

Simulations under different and contrasting environmental and management conditions were run and statistically tested. The model was validated against forest inventory data for the same sites and times and against true crown architectural data. The performance of the model for 6-year-old trees was encouraging. Total height, diameter and lengths of growth units were adequately estimated. Branch diameters were slightly overestimated. Wood density values were not satisfactory, but the cyclical pattern and increase of growth rings were reasonably well modelled.

Conclusions

The model was able to reproduce the development and growth of the species based on mechanistic formulations. It may be valuable in assessing stand behaviour under different environmental and management conditions, assisting in decision-making with regard to management, and as a research tool to formulate hypothesis regarding forest tree growth and development.     

Stem extension and mechanical stability of Xanthium canadense grown in an open or in a dense stand

Background and Aims

Plants in open, uncrowded habitats typically have relatively short stems with many branches, whereas plants in crowded habitats grow taller and more slender at the expense of mechanical stability. There seems to be a trade-off between height growth and mechanical stability, and this study addresses how stand density influences stem extension and consequently plant safety margins against mechanical failure.

Methods

Xanthium canadense plants were grown either solitarily (S-plants) or in a dense stand (D-plants) until flowering. Internode dimensions and mechanical properties were measured at the metamer level, and the critical buckling height beyond which the plant elastically buckles under its own weight and the maximum lateral wind force the plant can withstand were calculated.

Key Results

Internodes were longer in D- than S-plants, but basal diameter did not differ significantly. Relative growth rates of internode length and diameter were negatively correlated to the volumetric solid fraction of the internode. Internode dry mass density was higher in S- than D-plants. Young''s modulus of elasticity and the breaking stress were higher in lower metamers, and in D- than in S-plants. Within a stand, however, both moduli were positively related to dry mass density. The buckling safety factor, a ratio of critical buckling height to actual height, was higher in S- than in D-plants. D-plants were found to be approaching the limiting value 1. Lateral wind force resistance was higher in S- than in D-plants, and increased with growth in S-plants.

Conclusions

Critical buckling height increased with height growth due mainly to an increase in stem stiffness and diameter and a reduction in crown/stem mass ratio. Lateral wind force resistance was enhanced due to increased tissue strength and diameter. The increase in tissue stiffness and strength with height growth plays a crucial role in maintaining a safety margin against mechanical failure in herbaceous species that lack the capacity for secondary growth.     

宁夏六盘山三种针叶林初级净生产力年际变化及其气象因子响应

利用年轮生态学方法和生物量经验方程,在宁夏六盘山研究了华山松天然林及华北落叶松和油松人工林等3种针叶林的年初级净生产力(NPP)及其与气象因子间的关系。研究表明:3种针叶林生物量的年际变化均符合逻辑斯蒂方程,林分的现存生物量(t/hm2)为华北落叶松林最大(141.96),华山松林(130.99)次之,油松林最小(123.29)。3种针叶林NPP存在显著的年际差异和种间差异,林分的NPP(t.hm-.2a-1)为华北落叶松林(6.72)>油松林(5.76)>华山松林(2.66);NPP年际变化在华山松林呈现"快速增加-缓慢增加-缓慢减小"的趋势,而华北落叶松林和油松林为快速上升的趋势。3种针叶林的NPP随年降水量的变化行为不同,华山松林极轻微地增大,华北落叶松林和油松林均是先增加后降低;然而在极端干旱年份或极端湿润年份,3种针叶林的NPP都趋向于相同的较低值,其原因可能分别是水分胁迫和低温胁迫。气象因子对林分NPP的影响具明显的"滞后效应"和种间差异。华山松林NPP与上年11月和当年9、11月的降水量显著负相关;油松林NPP与上年9月及当年4月的降水量显著相关;上年和当年9月的降水量均与华北落叶松林NPP显著正相关。上年6月的温度和当年3与6月的月均温及月均最高温能显著影响3种针叶林的NPP,但存在种间差异,其中华山松林NPP与当年与上年生长季各月的温度均呈不同程度的负相关,而油松林和华北落叶松林则多呈不同程度的正相关。     

Isometric scaling of above- and below-ground biomass at the individual and community levels in the understorey of a sub-tropical forest

Background and Aims Empirical studies and allometric partitioning (AP) theory indicate that plant above-ground biomass (M_A) scales, on average, one-to-one (isometrically) with below-ground biomass (M_R) at the level of individual trees and at the level of entire forest communities. However, the ability of the AP theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs.Methods In order to test the AP theory further, 1586 understorey sub-tropical forest plants from 30 sites in south-east China were harvested and examined. The numerical values of the scaling exponents and normalization constants (i.e. slopes and y-intercepts, respectively) of log–log linear M_A vs. M_R relationships were determined for all individual plants, for each site, across the entire data set, and for data sorted into a total of 19 sub-sets of forest types and successional stages. Similar comparisons of M_A/M_R were also made.Key Results The data revealed that the mean M_A/M_R of understorey plants was 2·44 and 1·57 across all 1586 plants and for all communities, respectively, and M_A scaled nearly isometrically with respect to M_R, with scaling exponents of 1·01 for all individual plants and 0·99 for all communities. The scaling exponents did not differ significantly among different forest types or successional stages, but the normalization constants did, and were positively correlated with M_A/M_R and negatively correlated with scaling exponents across all 1586 plants.Conclusions The results support the AP theory’s prediction that M_A scales nearly one-to-one with M_R (i.e. M_A ∝ M_R^≈1·0) and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents of the M_A vs. M_R relationship. This feature of the results suggests that plant size is the primary driver of the M_A vs. M_R biomass allocation pattern for understorey plants in sub-tropical forests.     

Implication from the predicted docked interaction of sigma H and exploration of its interaction with RNA polymerase in Mycobacterium tuberculosis

M. tuberculosis is adapted to remain active in the extreme environmental condition due to the presence of atypical sigma factorscommonly called extra cytoplasmic function (ECF) sigma factors. Among the 13 sigma factors of M. tuberculosis, 10 are regarded asthe ECF sigma factor that exerts their attributes in various stress response. Therefore it is of interest to describe the structuralprediction of one of the ECF sigma factors, sigma H (SigH), involved in oxidative and heat stress having interaction with the β׳subunit of M. tuberculosis. RNA polymerase (Mtb-RNAP). The model of Mtb-SigH was build using the commercial package ofDiscovery Studio version 2.5 from Accelerys (San Diego, CA, USA) containing the inbuilt MODELER module and that of β׳ subunitof Mtb-RNAP using Phyre Server. Further, the protein models were docked using the fully automated web tool ClusPro(cluspro.bu.edu/login.php). Mtb-SigH is a triple helical structure having a putative DNA-binding site and the β׳ subunit of MtbRNAPconsists of 18-beta sheets and 22 helices. The SigH-Mtb-RNAP β׳ interaction studies showed that Arg26, Gln19 andAsp18,residues of SigH protein are involved in binding with Arg137, Gln140, Arg152, Asn133 and Asp144 of β׳ subunit of Mtb-RNAP.The predicted model helps to explore the molecular mechanism in the control of gene regulation with a novel unique target forpotential new generation inhibitor.     

Cytochrome c reactivity in its complexes with mammalian cytochrome c oxidase and yeast peroxidase

1.

1. The ascorbate reducibility of cytochrome c (beef or horse heart) in its complexes with cytochrome c oxidase (beef heart) and cytochrome c peroxidase (yeast) has been studied.     

First report of the presence of Acartia bispinosa Carl, 1907 (Copepoda,Calanoida) in a semi-enclosed Bay (Sharm El-Maya), northern Red Sea with some notes on its seasonal variation in abundance and body size

The calanoid copepod, Acartia bispinosa Carl, 1907, is reported for the first time in the Red Sea, where it is found to be an important copepod in the mesozooplankton community structure of the Sharm El-Maya Bay. Female and male are fully redescribed and illustrated of as the mouthparts of this species have never previously been described and figured. Acartia bispinosa was collected in the plankton samples throughout the year and showed two peaks of abundance, a pronounced one in April (4234 individuals m^-3), and second smaller peak during November (1784 individuals m^-3). The average total length of females varied between 1.32 and 1.53 mm at the end of June and January respectively. For males, the average total length fluctuated between 1.07 and 1.16 mm at end of June and March respectively. Temperature showed an inverse relationship with the body length (P > 0.001) and seemed to be one of the prime factors affecting the body length of both sexes.     

The equilibrium unfolding intermediate observed at pH 4 and its relationship with the kinetic folding intermediates in green fluorescent protein

Folding mechanisms of a variant of green fluorescent protein (F99S/M153T/V163A) were investigated by a wide variety of spectroscopic techniques. Equilibrium measurements on acid-induced denaturation of the protein monitored by chromophore and tryptophan fluorescence and small-angle X-ray scattering revealed that this protein accumulates at least two equilibrium intermediates, a native-like intermediate and an unfolding intermediate, the latter of which exhibits the characteristics of the molten globule state under moderately denaturing conditions at pH 4. To elucidate the role of the equilibrium unfolding intermediate in folding, a series of kinetic refolding experiments with various combinations of initial and final pH values, including pH 7.5 (the native condition), pH 4.0 (the moderately denaturing condition where the unfolding intermediate is accumulated), and pH 2.0 (the acid-denaturing condition) were carried out by monitoring chromophore and tryptophan fluorescence. Kinetic on-pathway intermediates were accumulated during the folding on the refolding reaction from pH 2.0 to 7.5. However, the signal change corresponding to the conversion from the acid-denatured to the kinetic intermediate states was significantly reduced on the refolding reaction from pH 4.0 to pH 7.5, whereas only the signal change corresponding to the above conversion was observed on the refolding reaction from pH 2.0 to pH 4.0. These results indicate that the equilibrium unfolding intermediate is composed of an ensemble of the folding intermediate species accumulated during the folding reaction, and thus support a hierarchical model of protein folding.     

林地覆盖对雷竹林土壤微生物特征及其与土壤养分制约性关系的影响

为了探讨林地覆盖雷竹林退化机理,给退化雷竹林恢复提供理论参考,对不同覆盖年限(CK、1、3 a 和6 a) 雷竹林土壤微生物区系组成和生物量碳(C_mic)、氮(N_mic)、磷(P_mic)等特征因子进行了测定,并分析了其与土壤养分的制约性关系。结果表明:(1) 雷竹林土壤微生物以细菌为主,真菌次之,放线菌最少,分别占土壤微生物总量的90.11%-98.03%、1.04%-9.22%和0.67%-1.37%。随覆盖年限增加,细菌、放线菌比率呈下降趋势,真菌比率呈上升趋势;土壤微生物总数、细菌和放线菌数量及C_mic、N_mic、P_mic均呈先升高后降低的变化趋势,试验雷竹林间差异极显著,真菌数量总体呈极显著升高趋势。(2)雷竹林土壤微生物特征因子与土壤有机质(SOM)、全氮(TN)、全磷(TP)、碱解氮(Available nitrogen, AN)和pH均呈显著或极显著相关,其中,CK和覆盖1 a、3 a雷竹林土壤微生物特征因子与土壤养分主要呈正相关,与pH呈负相关,而覆盖6 a雷竹林则相反。(3)不同覆盖年限雷竹林土壤养分与土壤微生物的制约性关系存在一定的差异,CK雷竹林土壤SOM、TN、AN、速效钾(AK)和pH主要影响土壤C_mic、N_mic和细菌,覆盖1 a雷竹林土壤SOM、TN、TP和AK主要影响土壤P_mic、放线菌和细菌,覆盖3 a雷竹林土壤SOM、TN、速效磷(AP)和AN主要影响土壤N_mic、放线菌和真菌,覆盖6 a雷竹林土壤SOM、TN和pH主要影响土壤N_mic、真菌。研究表明:长期覆盖雷竹林土壤细菌、放线菌数量与比例明显降低,真菌数量与比例明显提高,土壤养分与土壤微生物的制约性作用关系会发生较为明显变化,产生土壤障害,这是覆盖雷竹林退化的主要原因之一。     

8q12.1q12.3 de novo microdeletion involving the CHD7 gene in a patient without the major features of CHARGE syndrome: Case report and critical review of the literature

CHARGE syndrome is an autosomal dominant inherited disorder characterized by a specific and recognizable pattern of anomalies. De novo mutations or deletions of the gene encoding chromodomain helicase DNA binding protein 7 (CHD7) are the major cause of CHARGE syndrome. In this report, we describe a patient with a typical phenotype characterized by psychomotor retardation, hypertrichosis, facial asymmetry, synophria, failure to thrive, developmental delay and gastro-esophageal reflux, carrying a de novo 6.04 Mb interstitial deletion in 8q12.1q12.3 detected by single nucleotide polymorphism (SNP) array analysis. Despite the deletion includes CHD7 and although the patient shares some of the clinical features of the CHARGE syndrome, she does not fulfill the clinical criteria for this syndrome. To the best of our knowledge, this is the second case with an entire deletion of the CHD7 gene not leading to CHARGE syndrome and, for this reason, useful to expand and further delineate the clinical features associated with the 8q12.1q12.3 deletion. Furthermore, the literature review revealed that the phenotype secondary to duplications of the same region partially overlaps with the phenotype reported in this study. Selected genes that are present in the hemizygous state and which might be important for the phenotype of this patient, are discussed in context of the clinical features.     

Genetic structure,polymorphism identification of LGP2 gene and their relationship with the resistance/susceptibility to GCRV in grass carp, Ctenopharyngodon idella

Laboratory of genetics and physiology 2 (LGP2) is an actual detector and regulator during RNA viral infection in innate immunity. In this study, 5′-flanking region and all introns of LGP2 in grass carp (Ctenopharyngodon idella) were excavated. The genomic CiLGP2 (C. idella LGP2) was 8062 bp in length, with a 364 bp 5′-flanking region, twelve exons and eleven introns. Besides, the promoter activity of the upstream region before initiator codon was identified. By sequencing, six single nucleotide polymorphisms (SNPs) and one 20-bp insertion/deletion polymorphism were detected in CiLGP2. With a challenge experiment, the genotype and allele distributions of these seven polymorphisms were examined. Analytic result revealed only the − 1392 C/G, 494 A/T and 4403 C/T loci were significantly associated with the resistance/susceptibility to grass carp reovirus (GCRV) (P < 0.05). To further identify these correlations, another independent challenge test was performed. The analytic result based on the cumulative mortality demonstrated that the stock in − 1392 GG genotype was more susceptible to GCRV than that in CC genotype, while the stocks in 494 TT genotype and 4403 TT genotype were more resistant to GCRV than that in AA and CC genotype stocks, respectively (P < 0.05). Those significant SNPs might be potential gene markers for the future molecular selection of C. idella strains that are resistant to GCRV.     

A new small supernumerary marker chromosome involving 14pter → q12 in a child with severe neurodevelopmental retardation: Case report and literature review

Unstable, gene-rich pericentric regions have been associated with various structural aberrations including small supernumerary marker chromosomes (sSMCs). We hereby report on a new sSMC derived from chromosome 14, generating trisomy 14pter → q12 in a child with severe neurodevelopmental delay. The patient featured facial dysmorphism, generalized hypotonia, transverse palmar creases, structural brain abnormality, and severe cognitive and motor impairment. Literature review indicated this to be a unique case of sSMC 14 which was only composed of pter → q12, and the phenotype secondary to duplications of the similar region partially overlaps with the phenotype reported in this study. The genetic analysis on our case helps to better delineate karyotype–phenotype correlations between proximal trisomy 14 and associated clinical phenomena, and we also propose that the involved chromosomal regions may contain dosage-sensitive genes which are important for the development.     

Kinetics and thermodynamics of association of a fluorescent lysophospholipid derivative with lipid bilayers in liquid-ordered and liquid-disordered phases

We have measured the rates of insertion into, desorption from, and spontaneous interlayer translocation (flip-flop) of the fluorescent lysophospholipid derivative NBD-lyso-1-myristoylphosphatidylethanolamine in l(d) and l(o) phase lipid bilayer membranes. The lipid bilayers, studied as LUV, were prepared from pure 1-palmitoyl-2-oleoylphosphatidylcholine, in the l(d) phase; and from two Chol-containing binary lipid mixtures, 1-palmitoyl-2-oleoylphosphatidylcholine and Chol (molar ratio of 1:1) and SpM and Chol (molar ratio of 6:4), both in the l(o) phase. Insertion, desorption, and translocation rate constants and equilibrium constants for association of the amphiphile monomer with the lipid bilayers were measured between 15 degrees C and 35 degrees C, and the standard free energies, enthalpies, and entropies, as well as the activation energies for these processes were derived from these data. The equilibrium partition coefficients for partitioning of the amphiphile between the aqueous phase and the different membrane phases were also derived, and an estimation was made of hypothetical partition coefficients and the respective energetic parameters for partitioning between the different lipid phases if these were to coexist in the same membrane. We show that, contrary to general belief, the association of NBD-lysoMPE with lipid bilayers is not a diffusion-controlled process, the rate-limiting step in insertion being the formation of a free area in the membrane surface of an adequate size for insertion to occur.     

A novel t(4;16)(q25;q23.1) associated with EGF and ELOVL6 deregulation in acute myeloid leukemia

About 50% of acute myeloid leukemia (AML) patients show the occurrence of non-random chromosome rearrangements. Most of the recurrent karyotypic rearrangements in AML have been defined as distinct disease entities in the 2008 World Health Organization (WHO) classification. In this paper we report an AML case showing a novel t(4;16)(q25;q23.1) rearrangement causing the activation of epidermal growth factor (EGF) and elongation of long-chain fatty acids family member 6 (ELOVL6) genes, rather than the generation of a novel fusion gene.