A simple model of a Gyrodactylus population

Experimental populations of 20 Gyrodactylus alexanderi Mizelle &; Kritsky, 1967, on 19 isolated Gasterosteus aculeatus at 15°C increased for 2 weeks to a mean of 61, then decreased in 2 further weeks to a mean of 9. Fish that lost their fluke infestations were refractory to further infestation for about 3 weeks.The chief factors affecting fluke abundance were measured, including reproduction and mortality rates of flukes on fish, rate of shedding by the fish, mortality rates of flukes while off fish, and the rate of reattachment of the flukes. Data on these individual factors were combined to form a simple deterministic model which simulated the population changes on isolated fish. This was later made more realistic by the introduction of a random variable. When the model was tested in a multiple-host situation it predicted results close to those observed experimentally.     

The metabolic cost of fever in Pekin ducks

Fever is an energetically expensive component of the mammalian immune system’s acute phase response. Like mammals, birds also develop fever when exposed to pathogens, but, as yet, the energy requirements of febrile mediation in birds are not known. We injected ducks (Anas platyrhynchos; n=8) with 100 μ kg⁻¹ LPS or sterile isotonic saline and recorded their core body temperatures while measuring their O₂ consumption and CO₂ production in an open-flow respirometric circuit. Lipopolysaccharide elicited robust increases in the core body temperatures of our birds. The metabolic rate of the ducks increased about 80 min after treatment with LPS, relative to the metabolic rate of saline injected birds, and peaked 100 min later when the highest body temperatures were recorded. Our ducks increased their energy expenditure by 33.1% for about 3 h to mount a febrile response that, on average, increased their body temperature 1.4 °C. Studies with humans and rats, kept at thermoneutral temperatures, found a 10-15% increase in metabolic rate for every 1 °C increase in body temperature. The increase in metabolic rate, reported here (23%/°C), is noticeably higher and we conclude that febrile mediation is metabolically more expensive in Pekin ducks than in mammals.     

Genetic steady-state under BLUP selection for an infinite and homogeneous population with discrete generations

A matrix derivation is proposed to analytically calculate the asymptotic genetic variance-covariance matrix under BLUP selection according to the initial genetic parameters in a large population with discrete generations. The asymptotic genetic evolution of a homogeneous population with discrete generations is calculated for a selection operating on an index including all information (pedigree and records) from a non-inbred and unselected base population (BLUP selection) or on an index restricted to records of a few ancestral generations. Under the first hypothesis, the prediction error variance of the selection index is independent of selection and is calculated from the genetic parameters of the base population. Under the second hypothesis, the prediction error variance depends on selection. Furthermore, records of several generations of ancestors of the candidates for selection must be used to maintain a constant prediction error variance over time. The number of ancestral generations needed depends on the population structure and on the occurrence of fixed effects. Without fixed effects to estimate, accounting for two generations of ancestors is sufficient to estimate the asymptotic prediction error variance. The amassing of information from an unselected base population proves to be important in order not to overestimate the asymptotic genetic gains and not to underestimate the asymptotic genetic variances.     

承载力评估在区域人口配置中的应用:以常州为例

从城市生态系统承载力的空间差异性出发,集成GIS空间评价技术和系统动力学(SD)模型,确定城市区域适度总人口规模和各分区人口数量,提出人口分区定量配置新思路和技术集成方法,并将该方法应用于300万人口城市——常州.结果表明:通过构建常州市区人口、经济、土地与环境的系统动力学模型和多情景模拟分析,在同时满足城市经济发展与环境保护需求下,常州市区远景(2050年)总人口约400万;基于城市承载力空间差异评价进行常州市区总人口的空间配置,将形成240万人的主城及5个15 ～ 40万人新城的空间格局,研究结果可为国土开发管理中人口与经济的空间分配提供科学依据.     

基于综合承载力的吉林省适度人口分析

运用状态空间法构建区域适度人口模型,利用主成分分析求取权重,对2005—2014年吉林省适度人口进行测算,并探讨其形成原因,提出解决对策.结果表明: 2005—2014年,吉林省适度人口一直处于赤字状态,说明吉林省人口、资源与环境处于一种不协调状态;吉林省资源承载人口显著高于经济承载人口和生态承载人口,说明吉林省经济发展是以牺牲环境为代价;吉林省土地资源承载人口远高于水资源承载人口和能源承载人口,处于赤字状态,说明吉林省经济发展是以耗竭自身能源和水资源为基础.今后应因地制宜,提高水资源承载力;开发新能源,提高能源利用效率;由粗放型、消耗型资源利用方式向集约型、低碳型转变;改变人类的生产方式和消费模式,注重保护生态环境.     

Plant-capture estimation of the size of a homogeneous population

We consider maximum likelihood estimation of the size of a targetpopulation to which has been added a known number of plantedindividuals. The standard equal-catchability model used in mark-recaptureis assumed to be applicable to the augmented population. Afterproving the unimodality of the profile likelihood for the targetpopulation size, we obtain both the maximum likelihood estimatorof this size and interval estimators based on its asymptoticdistribution.     

Growth of swimming muscles and its metabolic cost in larvae of whitefish at different temperatures

The temperature relationship of routine metabolic rate (R_r) of non-feeding, non-growing Coregonus lavaretus larvae between 2 and 15°C is characterized by Q₁₀-values ranging from l.8-2.45. The rate of growth, based on weight determinations, of first-feeding larvae amounted to 3.5, 7.6 and 9.4% day-¹ at 5, 10 and 12°C respectively, from which Q₁₀-values between 4.0 and 4.8 can be calculated. The rate of increase of muscle mass between 5 and 10°C, based on the determination of the cross-sectional area of inner muscle fibres, resulted in a Q₁₀-value of 4.5. Water temperature influenced the pattern of growth of the inner muscle fibres. At hatching, after 360 day degrees, total muscle mass of larvae reared at 4 and 8°C was independent of temperature, but at 4°C the rate of mass increase owed more to hyperplasia (increase in fibre number) than to hypertrophy (increase in fibre mass), whereas at 8°C the opposite was the case. The calculation of power budgets (including the metabolic cost of growth) of first-feeding larvae yielded net conversion efficiencies (K₂) increasing with temperature from 46.3% at 5°C to 54.7% at 12°C. Comparing our data with literature data two general conclusions can be drawn. (1) In first-feeding larvae the net, but not the gross, conversion efficiency of food energy increases with temperature. This is due to net energy input being characterized by a much higher Q₁₀-value than energy expenditures. (2) In embryos of freshwater fish so far investigated hyperplasia plays a greater role in the increase of fibre mass than hypertrophy at the lower temperature, whereas in embryos of marine fish hyperplasia prevails at the higher temperature. It is suggested that this discrepancy correlates with the high concentration of free amino acids in the eggs of marine species which provide an additional, easily available, source of metabolic energy absent in freshwater species.     

黑龙江凤凰山国家级自然保护区野猪冬季容纳量及最适种群密度

近年黑龙江省凤凰山国家级自然保护区野猪数量不断增长,人猪冲突加剧,保护区资源保护管理工作面临较大管理压力.为确定野猪种群的实际数量,同时评估该保护区的野猪的容纳量水平,以便为保护区管理局针对野猪的管理提供相关指导意见.2009-2010年冬季,在保护区采用样带调查、雪地足迹链跟踪和观察食痕的方法,并结合已有野猪生态研究确定野猪食性.野猪主要食物种类包括:木贼(Equisetum hiemale)、红松(Pinus koraiensis)果实松籽、胡桃楸(Juglans mandshurica)果实核桃、蒙古栎(Quecusmongolica)果实橡子、稠李(Padus racemosa)、榛子(Corylus heterophlla)、苔草(Carex spp.)、辽东葱木(Aralia elata).研究期间共布设长3-5km、单侧宽度50m、总长134 km的样带30条.调查中,每隔200 m布设10 m×10 m的大样方,并在每个大样方中央及四角布设1 m×1 m的小样方,共布设大样方350个,小样方1 750个.通过样方调查,统计野猪栖息生境当年可食植物枝条及其食物种类,然后计算其食物的总供给量,再结合食物营养成分,通过粗蛋白、粗纤维、粗脂肪的能量转换,按照每克粗蛋白和粗纤维的能量转换系数为16.74kJ、每克粗脂肪的能量转换系数为37.66 kJ,确定野外生境食物总能量供给.结合野猪冬季日营养需求,以能量为基础估算保护区野猪的营养容纳量.在种群密度调查过程中,通过足迹链判断个体方法为:单一清晰足迹链确定为一个体所留,30m内多条足迹穿越同一样带被认为是一个野猪群所留,调查中根据个体分开时的足迹链数确定野猪个体数,同时将粪便、卧迹、啃食痕迹作为个体判断的辅助信息.研究结果表明:凤凰山保护区内能够提供的总能量为7.375 ×107MJ,冬季平均每头野猪生存所需能量为(14 677.698±409.92) MJ,野猪营养容纳量为(1 006±28)头,种群密度为(3.79±0.11)头/km2.此外,调查中发现30余个野猪套及2头野猪被猎杀现场,反应出当地的人猪冲突较为严重.结合调查中发现的野猪套数量及野猪被猎杀概率,对野猪种群数量引入20％的死亡风险系数.最终确定凤凰山野猪种群的最适数量在(603±17)头左右,最适密度为(2.27±0.06)头/km2.通过样带法调查得出凤凰山自然保护区实际野猪种群数量为(596±155)头,密度(2.24±0.58)头/km2,已趋近营养容纳量.因此,野猪并未过量,不能采取狩猎等降低种群数量的措施,同时保护区也应对野猪种群进行持续监控,防止野猪种群过度繁殖以至成灾.     

Power and metabolic scope of bird flight: a phylogenetic analysis of biomechanical predictions

For flying animals aerodynamic theory predicts that mechanical power required to fly scales as P proportional, variant m (7/6) in a series of isometric birds, and that the flight metabolic scope (P/BMR; BMR is basal metabolic rate) scales as P (scope) proportional, variant m (5/12). I tested these predictions by using phylogenetic independent contrasts from a set of 20 bird species, where flight metabolic rate was measured during laboratory conditions (mainly in wind tunnels). The body mass scaling exponent for P was 0.90, significantly lower than the predicted 7/6. This is partially due to the fact that real birds show an allometric scaling of wing span, which reduces flight cost. P (scope) was estimated using direct measurements of BMR in combination with allometric equations. The body mass scaling of P (scope) ranged between 0.31 and 0.51 for three data sets, respectively, and none differed significantly from the prediction of 5/12. Body mass scaling exponents of P (scope) differed significantly from 0 in all cases, and so P (scope) showed a positive body mass scaling in birds in accordance with the prediction.     

Spatial subdivision within a population of tropical pythons (Liasis fuscus) in a superficially homogeneous habitat

Abstract Based on 10 years of intensive fieldwork, we describe the spatial and temporal distribution of water pythons (Liasis fuscus) on the Adelaide River floodplain, Northern Territory, Australia. Our study provides a cautionary tale, because it was only after several years’ work that we realized that our apparently panmictic study ‘population’ in fact consisted of three subpopulations that were separated during breeding activities although they intermingled for most of the year. The partitioning of the populations is due to the restricted availability and spatial separation of suitable nest-sites (varanid burrows vs root complexes of paperbark trees). Groups of snakes using each type of nest-site comprise quite separate breeding populations, because females move to these sites prior to mating. Snakes return to the same breeding sites year after year, with little dispersal between populations (even though snakes from each population often move through other breeding sites during the non-breeding period). The three subpopulations differed in many traits, including body-size distributions, age structures, the proportions of reproductive animals, survival rates, timing of reproduction, and reproductive frequencies. Thus, if our study had involved only one of the subpopulations (as would typically be the case with studies of this kind), we would have obtained a misleading view of the ‘real’ (i.e. average) ecological characteristics of our study organisms.     

Information capacity of nucleotide sequences and Its applications

The information capacity of nucleotide sequences is defined through the specific entropy of frequency dictionary of a sequence determined with respect to another one containing the most probable continuations of shorter strings. This measure distinguishes a sequence both from a random one, and from ordered entity. A comparison of sequences based on their information capacity is studied. An order within the genetic entities is found at the length scale ranged from 3 to 8. Some other applications of the developed methodology to genetics, bioinformatics, and molecular biology are discussed.     

Individual variation and population dynamics: lessons from a simple system

The mapping of environment, through variation in individuals' life histories, to dynamics can be complex and often poorly known. Consequently, it is not clear how important it is dynamically. To explore this, I incorporated lessons from an empirical system, a soil mite, into an individual-based model. Individuals compete for resource and allocate this according to eight 'genetic' rules that specify investment in growth or reserves (which influences survival or fecundity), size at maturation and reproductive allocation. Density dependence, therefore, emerges from competition for food, limiting individual's growth and fecundity. We use this model to examine the role that genetic and phenotypically plastic variation plays in dynamics, by fixing phenotypes, by allowing phenotypes to vary plastically and by creating genetic variation between individuals. Variation, and how it arises, influences short- and long-run dynamics in a way comparable in magnitude with halving food supply. In particular, by switching variation on and off, it is possible to identify a range of processes necessary to capture the dynamics of the 'full model'. Exercises like this can help identify key processes and parameters, but a concerted effort is needed across many different systems to search for shared understanding of both process and modelling.     

Heterogeneity in the endocytic capacity of individual macrophage in a population determines its subsequent phagocytosis,infectivity and subcellular trafficking

Phagocytosis is a complex cellular uptake process involving multiple distinct steps of cargo recognition, uptake, phagosome maturation and eventual phagolysosome resolution. Emerging literature shows that heterogeneity of phagocytosis at multiple steps at a single cell level influences the population outcome. However, the determinants of phagocytic heterogeneity are not clear. Here we show that the variance in the endocytic capacity of individual cells in a macrophage population determines subsequent phagocytic uptake and trafficking. Our results document the extensive heterogeneity in the endocytic uptake of individual macrophages, and show that cells with higher endocytic capacity preferentially phagocytose diverse cargo, including pathogenic Mycobacterium tuberculosis. Interestingly, M. tuberculosis infected cells sustain the higher endocytic capacity following infection. Modulating endocytic capacity by inhibiting endocytosis reduces phagocytic uptake. Differential uptake of M. tuberculosis into cells with different endocytic capacities correlates with the efficiency of phagocytic delivery to lysosomes, thus contributing further to phagocytic as well as mycobacterial heterogeneity. Thus, variance in endocytic capacity is a determinant of generating heterogeneity in phagocytosis at multiple steps.     

Association of the C825T polymorphism in the GNB3 gene with obesity and metabolic phenotypes in a Taiwanese population

The relationship between obesity and a single nucleotide polymorphism (SNP), rs5443 (C825T), in the guanine nucleotide binding protein beta polypeptide 3 (GNB3) gene is currently inconsistent. In this study, we aimed to reassess whether the GNB3 rs5443 SNP could influence obesity and obesity-related metabolic traits in a Taiwanese population. A total of 983 Taiwanese subjects with general health examinations were genotyped. Based on the criteria defined by the Department of Health in Taiwan, the terms “overweight” and “obesity” are defined as 24 ≦ BMI < 27 and BMI ≧ 27, respectively. Compared to the carrier of the combined CT + TT genotypes of the GNB3 rs5443 polymorphism, triglyceride was significantly higher for the carrier of CC genotype in the complete sample population (128.2 ± 93.2 vs. 114.3 ± 79.1 mg/dl; P = 0.041). In addition, the carriers of CC variant had a higher total cholesterol than those with the combined CT + TT variants (194.5 ± 36.8 vs. 187.9 ± 33.0 mg/dl; P = 0.019) in the complete sample population. In the normal controls, both triglyceride (P = 0.018) and total cholesterol (P = 0.011) were also significantly higher in the CC homozygotes than in the combined CT + TT genotypes. However, the GNB3 rs5443 SNP did not exhibit any significant association with obesity or overweight among the subjects. Our study indicates that the CC genotype of the GNB3 rs5443 SNP may predict higher obesity-related metabolic traits such as triglyceride and total cholesterol in non-obese Taiwanese subjects (but not in obese subjects).     

Plasticity, its cost, and phenotypic selection under water and nutrient stress in two annual grasses

A comparative approach can prove to be a useful tool for studying phenotypic plasticity, if applied to specific traits involved in adaptation to particular environment in more than one species across co-located populations. The present study tested whether two annual grasses, Hordeum spontaneum and Avena sterilis , belonging to the same guild, having similar stature, seed dispersal mechanism, breeding system, and genetic variation, and sampled in exactly the same environmentally specific locations, differed with respect to: (1) plasticity in traits involved in adaptation, namely the onset of reproduction and maternal investment involving the number of inflorescences, spikelets per inflorescence, the weight of individual spikelets, and abortion rate; (2) the cost of this plasticity, and (3) the pattern of phenotypic selection on the above traits. The two species exhibited highly differing amounts of phenotypic plasticity in the onset of flowering and several reproductive traits (number of inflorescences, spikelets per inflorescence, abortion rate), but no plasticity costs in any experimental environment. The two species demonstrated a decreasing similarity in the regulation of reproduction in four experimental environments: benign, water, nutrients and water × nutrient deficient. Correlational selection appears to contribute, although not solely, to the observed species differences with respect to the regulation of reproduction.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 581–593.     

Relationship between urinary heavy metals with metabolic syndrome and its components in population from Hoveyzeh cohort study: A case-control study in Iran

BackgroundThe incidence of Metabolic Syndrome (MetS) has been growing rapidly and is rising to pandemic proportions. Although obesity is a primary risk factor for the enhancement of these conditions, not all obese individuals develop metabolic syndrome, indicating that the risk for developing MetS is impacted by other genetic and/or environmental factors such as heavy metals. Therefore, the present study focused on the association between exposures to heavy metal and MetS.MethodsUrine samples were collected from 150 participants (75 patients with MetS and 75 healthy participants), which were used from Hoveyzeh Cohort center. To make a quantitative comparison between the two groups, Man-Whitney nonparametric test was used. The logistic regression was performed adjusted for age, demographic, lifestyle factor, physical activity, occupational history and urine creatinine.ResultsThe results of logistic regression showed that OR and 95 % CI for Cd, Pb, Sr, As and Fe concentration were still significant after adjusting for urine creatinine. Moreover, there was a relationship between Cd and Pb levels and waist circumstance (WC). After adjusting for urine creatinine, age, sex, occupation, smoking status, education and place of residence, only Pb concentration was showed a significant association with systolic blood pressure (SBP). The subjects with high urine level of Cd had the high odds (OR: 6.273; 95 % Cl: 1.783–22.070) of MetS and low high-density lipoprotein (HDL-C). The relationship between As concentration and high fasting blood sugars confirmed the previous evidence suggesting that high As level can cause diabetes.ConclusionThese results indicated that outbreak of MetS and its component are associated with heavy metal concentrations in urine.     

High levels of plasma selenium are associated with metabolic syndrome and elevated fasting plasma glucose in a Chinese population: A case-control study

BackgroundSelenium is important for human health and involved in various metabolic processes. Deficiency of selenium associates with increased risk for cancer and cardiovascular diseases. There has been an increase use of selenium supplements for the treatment of autoimmune thyroid conditions. However, the potential biological effects of selenium overload arouse the public concern. The aim of this study was to investigate the associations of plasma selenium concentrations of adults with metabolic syndrome (MS) in Chinese population.MethodsA matched case-control study including 204 metabolic syndrome patients and 204 healthy controls was conducted in 2012. The MS cases were defined according to the criteria of Chinese Diabetes Society (CDS). Healthy controls without abnormality of metabolic components were matched with cases in age, gender and region. Plasma concentrations of selenium were determined by graphite furnace atomic absorption spectrometry (GFAAS). Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL), and low density lipoprotein cholesterol (LDL) were detected by automatic biochemical analyzer.ResultsThe median levels of plasma selenium in MS group were 146.3 (107.3–199.4) μg/L, which were significantly higher than that in the control group (127.4: 95.7–176.0) μg/L; Plasma levels of selenium were related to the risk of MS in dose-response manner. Risk of MS was significantly higher in subjects with plasma selenium in the highest tertile (T3: ≥176.0 μg/L) compared to those in the lowest tertile (T1: <95.7 μg/L) [odds ratio (OR) = 2.416 (95% CI: 1.289–4.526)]. The plasma levels of selenium were positively correlated with fasting plasma glucose (FPG) (r_s = 0.268, P < 0.001). Plasma selenium at the median (T2: 95.7–176.0 μg/L) or upper tertile (T3: ≥176.0 μg/L) was associated with increased risk of elevated FPG (defined by FPG ≥ 6.1 mmol/L) as compared with the lowest tertile (T1: ≤95.7 μg/L) [T2 vs. T1, OR = 3.487 (1.738–6.996); T3 vs. T1, OR = 6.245 (3.005–12.981)].ConclusionsHigher levels of plasma selenium might increase the risk of metabolic syndrome and elevated fasting plasma glucose. Selenium supplements should be used with prudence for CVD and cancer prevention.     

Application of a simple unstructured kinetic and cost of goods models to support T-cell therapy manufacture

Manufacturing of cell therapy products requires sufficient understanding of the cell culture variables and associated mechanisms for adequate control and risk analysis. The aim of this study was to apply an unstructured ordinary differential equation-based model for prediction of T-cell bioprocess outcomes as a function of process input parameters. A series of models were developed to represent the growth of T-cells as a function of time, culture volumes, cell densities, and glucose concentration using data from the Ambr®15 stirred bioreactor system. The models were sufficiently representative of the process to predict the glucose and volume provision required to maintain cell growth rate and quantitatively defined the relationship between glucose concentration, cell growth rate, and glucose utilization rate. The models demonstrated that although glucose is a limiting factor in batch supplied medium, a delivery rate of glucose at significantly less than the maximal specific consumption rate (0.05 mg 1 × 10⁶ cell h⁻¹) will adequately sustain cell growth due to a lower glucose Monod constant determining glucose consumption rate relative to the glucose Monod constant determining cell growth rate. The resultant volume and exchange requirements were used as inputs to an operational BioSolve cost model to suggest a cost-effective T-cell manufacturing process with minimum cost of goods per million cells produced and optimal volumetric productivity in a manufacturing settings. These findings highlight the potential of a simple unstructured model of T-cell growth in a stirred tank system to provide a framework for control and optimization of bioprocesses for manufacture.