Point pattern analysis of different age-classes of Larix principis-rupprechtii in Luya Mountain Reserve, Shanxi Province, China

Larix principis-rupprechtii forest is an important vegetation formation and has a large distribution area in Luya Mountain Reserve,China.Spatial pattern analysis on individual trees in different age-classes of Larix principisrupprechtii was made in this paper.Here,we employed the technique of point pattern analysis,which could analyze patterns under all scales along a gradient.It was based on spatial mapped points of individual distribution.The results of this study showed that the densities of the five age-classes varied in the order:age-class 3＞age-class 4＞age-class 5＞age-class 2＞age-class 1.Although age-classes 1 and 2 have much fewer individuals than other three age-classes do,the population was stable at present.However,it would be necessary to take some measures for improving population regeneration for a long-time view.The individuals of all age-classes focused on clumping distribution in space;however,their distribution pattern varied with the change of scale.This mainly depended on biological features of Larix principis-rupprechtii and forest environments,but it also meant that the scale was an important factor in controlling spatial distribution pattern of tree individuals.The feature of clumping distribution became more significant with the increase of age.The relationships between individuals in different age-classes were almost all significantly correlated with each other.These associations became more significant within the older age-classes.This suggested that the individuals of different age-classes were interdistributed,by which the population could get benefits in resource utilization.The technique of point pattern analysis is effective and easy to be used in species pattern study.Its results are more closer to the reality,especially for community structure.     

三个玉米合成群体选系的配合力及杂种优势分析

采用NCⅡ遗传交配设计,通过在黑龙江省哈尔滨和泰来的两点试验,以玉米自交系Mo17、B73、444和丹340为测验种,对从群体品综1号、中综3号和陕综5号选育的18份自交系进行配合力及杂种优势分析,以探讨群体选系在我国东北早熟玉米区的利用途径。结果表明,供试自交系间一般配合力存在较大差异;陕综5号群体选系HR14、HR17和HR15、中综3号选系HR9和HR8、品综1号选系HR4的一般配合力较高。在供试的72个组合中HR15×丹340、HR17×丹340、HR9×Mo17、HR14×丹340、HR7×B73、HR8×B73、HR6×444、HR5×丹340产量的特殊配合力及对照优势较高,表现出较高的利用潜力。依据特殊配合力及对照优势分析,中综3号选系与旅大红骨群、陕综5号选系与兰卡斯特群、品综1号选系与瑞德群遗传关系较近。结合育种实践,在我国北方早熟春玉米区陕综5号×旅大红骨、中综3号×瑞德或兰卡斯特、品综1号×旅大红骨或唐四平头可能组成较大利用潜力的杂种优势模式。     

Minimum population size,genetic diversity,and social structure of the Asian elephant in Cat Tien National Park and its adjoining areas,Vietnam, based on molecular genetic analyses

Vietnam’s elephant population that has suffered severe declines during the past three decades is now believed to number 60–80 individuals in the wild. Cat Tien National Park is thought to be one of the key areas for the recovery of Vietnam’s elephants. We carried out a molecular genetic study of elephants in Cat Tien National Park and its adjoining areas with the objectives of estimating minimum population size, assessing genetic diversity, and obtaining insights into social organization. We obtained a minimum population size of 11 elephants based on a combination of unique nuclear microsatellite genotypes and mitochondrial haplotypes. While mitochondrial diversity based on a 600-base pair segment was high in this small sample of individuals, the six microsatellite loci examined showed low diversity and the signature of a recent population bottleneck. Along with nuclear genetic depauperation of Cat Tien’s elephants, we also report disruption of normal social organization, with different matrilines having coalesced into a single social group because of anthropogenic disturbance. The results emphasize the critical condition of this elephant population and the need for urgent conservation measures if this population is to be saved.     

Density functional study of closed-shell attraction on X(ML)<Subscript>3</Subscript><Superscript>+</Superscript>(<Emphasis Type="Italic">X</Emphasis> = O,S, Se; <Emphasis Type="Italic">M</Emphasis> = Au,Ag, Cu) systems

With the help of quantum mechanical calculations, we have examined the series of central system X(ML)₃ ⁺(X = O, S, Se; M = Au, Ag, Cu). Using a scalar–relativistic density functional approach, we studied the geometry structures, Mulliken populations and charges of the systems. Structure parameters of the experimental systems are reproduced well with Xα method. The metallophilic interaction energy is analyzed and decomposed. For the systems with different central atoms and different metal atoms, the nature of the metallophilic attraction interaction is analyzed.     

The synthesis of artificial genome as the basis of synthetic biology

Recent achievements in the whole-genome sequencing especially viral and bacterial ones together with the development of methods of bioinformatics and molecular biology, have created preconditions for transition from synthesis of genes to assembly of the whole genomes based on chemically synthesized blocks, oligonucleotides. The creation of artificial genomes and artificial cells will undoubtedly render huge influence on a deepening of knowledge on mechanisms of functioning of living systems at a cellular level, on a way of origin and evolution of life, and also on biotechnology of the future, and will generate preconditions for the further development of synthetic biology and nanobiotechnology.     

Pitfalls to avoid in nonlinear perturbation analysis of structured population models

Despite the ubiquity of nonlinear functional relationships in nature we tend to characterize mechanisms in science using more tractable linear functions. In demographic modeling, transfer function analysis is used to calculate the nonlinear response of population growth rate to a theoretical perturbation of one or more matrix elements. This elegant approach is not yet popular in ecology. Inconveniently, using transfer function without care can produce erroneous results without warning. We used a large matrix projection model database to explore the potential pitfalls to be avoided in using transfer function analysis. We asked a fundamental population control question, what matrix element perturbation would be needed to reach a minimum goal of replacement population growth? We then tracked instances in which transfer function yields erroneous output and explored these cases in detail to measure how frequently it occurs. We developed a phylogenetically-corrected mixed effects logistic regression model in a Bayesian framework to test the effect of species traits and the identity of matrix elements on the probability that transfer function yields errors. We found in 16% of cases the transfer function yielded erroneous outcomes. These errors were more likely when perturbing demographic stasis and also for shrubs more than any other life form. Errors in transfer function analysis were often due to perturbing matrix elements beyond their biological limits, even when this is still mathematically correct. To use transfer function analysis properly in demographic modeling and avoid erroneous results, input must be carefully selected to include only a biologically admissible set of perturbations.     

Insect pest management in the age of synthetic biology

Arthropod crop pests are responsible for 20% of global annual crop losses, a figure predicted to increase in a changing climate where the ranges of numerous species are projected to expand. At the same time, many insect species are beneficial, acting as pollinators and predators of pest species. For thousands of years, humans have used increasingly sophisticated chemical formulations to control insect pests but, as the scale of agriculture expanded to meet the needs of the global population, concerns about the negative impacts of agricultural practices on biodiversity have grown. While biological solutions, such as biological control agents and pheromones, have previously had relatively minor roles in pest management, biotechnology has opened the door to numerous new approaches for controlling insect pests. In this review, we look at how advances in synthetic biology and biotechnology are providing new options for pest control. We discuss emerging technologies for engineering resistant crops and insect populations and examine advances in biomanufacturing that are enabling the production of new products for pest control.     

Marine and freshwater regime changes impact a community of migratory Pacific salmonids in decline

Marine and freshwater ecosystems are increasingly at risk of large and cascading changes from multiple human activities (termed “regime shifts”), which can impact population productivity, resilience, and ecosystem structure. Pacific salmon exhibit persistent and large fluctuations in their population dynamics driven by combinations of intrinsic (e.g., density dependence) and extrinsic factors (e.g., ecosystem changes, species interactions). In recent years, many Pacific salmon have declined due to regime shifts but clear understanding of the processes driving these changes remains elusive. Here, we unpacked the role of density dependence, ecosystem trends, and stochasticity on productivity regimes for a community of five anadromous Pacific salmonids (Steelhead, Coho Salmon, Pink Salmon, Dolly Varden, and Coastal Cutthroat Trout) across a rich 40-year time-series. We used a Bayesian multivariate state-space model to examine whether productivity shifts had similarly occurred across the community and explored marine or freshwater changes associated with those shifts. Overall, we identified three productivity regimes: an early regime (1976–1990), a compensatory regime (1991–2009), and a declining regime (since 2010) where large declines were observed for Steelhead, Dolly Varden, and Cutthroat Trout, intermediate declines in Coho and no change in Pink Salmon. These regime changes were associated with multiple cumulative effects across the salmon life cycle. For example, increased seal densities and ocean competition were associated with lower adult marine survival in Steelhead. Watershed logging also intensified over the past 40 years and was associated with (all else equal) ≥97% declines in freshwater productivity for Steelhead, Cutthroat, and Coho. For Steelhead, marine and freshwater dynamics played approximately equal roles in explaining trends in total productivity. Collectively, these changing environments limited juvenile production and lowered future adult returns. These results reveal how changes in freshwater and marine environments can jointly shape population dynamics among ecological communities, like Pacific salmon, with cascading consequences to their resilience.     

Electrogenetics: Bridging synthetic biology and electronics to remotely control the behavior of mammalian designer cells

Electrogenetics, the combination of electronics and genetics, is an emerging field of mammalian synthetic biology in which electrostimulation is used to remotely program user-designed genetic elements within designer cells to generate desired outputs. Here, we describe recent advances in electro-induced therapeutic gene expression and therapeutic protein secretion in engineered mammalian cells. We also review available tools and strategies to engineer electro-sensitive therapeutic designer cells that are able to sense electrical pulses and produce appropriate clinically relevant outputs in response. We highlight current limitations facing mammalian electrogenetics and suggest potential future directions for research.