Relationships Among pH,Minerals, and Carbon in Soils from Tundra to Boreal Forest Across Alaska

Tundra and boreal forests in northern high latitudes contain significant amounts of carbon (C) in the soil, indicating the importance of clarifying controls on soil C dynamics in the region and their feedback effects on climate systems. In northern Alaska, variations in soil C processes are closely associated with variations in soil acidity within ecosystems; however, the reason for this association remains unclear. In this study, we demonstrate that it results from weathering and subsequent changes in soil geochemical characteristics, including minerals and adsorptive organic C. We sampled soils from 12 sites in Alaska along a 600-km transect from the Arctic Ocean to interior Alaska, spanning the biomes of tundra, tundra–boreal forest ecotone, and boreal forest. Mineral soil analyses revealed that soils with low pH have fewer base cations, more aluminum/iron minerals, and lower base saturation, indicating that weathering is a major function of these geochemical characteristics in the broad area over northern Alaska. Adsorbed organic C in soil presented strong correlations with Al and Fe minerals, soil pH, and soil total C and represented approximately 30–55% of total soil C, suggesting that soil C accumulation in the Alaskan ecosystems is strongly controlled by weathering-related changes in geochemical characteristics. An adsorption test supported these observations and illustrated a greater capacity for acidic soil to adsorb organic C. These findings demonstrate that variations in weathering-associated characteristics have a strong influence on the regional variation in C dynamics and biogeochemical consequences in the Alaskan ecosystems.     

环境pH及渗透压对玫瑰无须鲃精子运动的影响

以玫瑰无须鲃Puntius conchonius精子为材料,应用计算机辅助精子分析系统(CASA),研究了精子在不同pH和不同渗透压的NaCl溶液中的运动百分率、运动时间和运动速率。结果表明,酸性(pH<7.0)或碱性较强(pH>9.0)的溶液均不利于精子运动,而弱碱性(pH7.5～8.5)的溶液较适合精子的运动;在渗透压较低(<75mOsm/kg)或较高(>175mOsm/kg)的NaCl溶液中,精子的运动时间和运动百分率都显著较100～150mOsm/kg渗透压溶液中的短或低(P<0.05);而运动时间最长,并且运动百分率最高的条件为pH8.0和125mOsm/kg渗透压的溶液环境。     

Relationships Among Circadian Typology,Psychological Symptoms,and Sensation Seeking

Recently, attention has been focused on the relationship among circadian typology, psychiatric symptoms, and personality traits. This study analyzes the influence of circadian typology on psychological distress, and the sensation-seeking personality trait. Five hundred seventeen college students (173 males), aged 17 to 30, answered the Composite Scale of Morningness (CSM), the General Health Questionnaire 28-item version (GHQ-28), and the Sensation Seeking Scale-V (SSS-V). The evening-type subjects in our sample scored higher than the neither- and morning- type in the GHQ-28 total score, as well as in the four subscales that composed it (Psychosomatic Symptoms, Anxiety and Insomnia, Social Dysfunction, and Severe Depression) (p?<?0.02 in all cases). The evening-type subjects also had a larger proportion of psychiatric cases than the other two circadian typologies (p?<?0.0001 in all cases). Moreover, the evening-type subjects obtained higher scores in the SSS-V total score and in the subscales of Disinhibition and Boredom Susceptibility (p?<?0.001 in all cases). A positive correlation was observed between the GHQ-28 and the SSS-V total scores in the total sample, but only for the evening-type group (r?=?0.217; p?<?0.027). In the evening group, several relations were also found between the subscales of the GHQ-28 and the subscales of the SSS-V (r?>?0.206; p?<?0.036). All these data point to a relationship between evening-type subjects and the level of psychological distress and the sensation-seeking personality trait. They also suggest that eveningness could be related to developing psychological distress and personality traits that could, in turn, be related to developing other problems, such as drug consumption.     

The Relationships Among Disturbance, Substratum Size and Periphyton Community Structure

Numerous studies have determined the effects of physical disturbance on periphyton, however, the substrata used have varied in size among studies. In this study we examined the influence of substratum size on the change in periphyton exposed to three levels of disturbance. Periphyton communities were established in a large greenhouse tank on square unglazed tiles that were either 2.5, 5, or 7.5 cm on a side. Following community development sets of tiles were randomly assigned to controlled disturbances removing 25%, 50%, or 75% of the community or an undisturbed control. Following disturbance, changes in periphyton density were associated with both disturbance treatment and tile size as was taxa richness. Experimental results and direct observation revealed that algal growth was most concentrated along the edge of the tile and progressively declined toward the center. Thus, substratum size influences colonization and pre-disturbance community structure, which then affects the extent of periphyton community change due to different levels of disturbance.     

Relationships Among Coagulase, Enterotoxin, and Heat-stable Deoxyribonuclease Production by Staphylococcus aureus

The relationship between heat-stable deoxyribonuclease and coagulase production was investigated in the interest of developing more rapid diagnostic and quantitative procedures for distinguishing toxigenic and pathogenic staphylococci from closely related saprophytic organisms.     

培养液及其浓度和pH值对草履虫种群增长的影响

采用稻草、小麦、奶粉、酵母、玉米粒、荷叶等6种培养液培养草履虫,结果表明,稻草、玉米粒和奶粉培养液为草履虫的理想培养液。另外,对上述3种理想培养液的不同浓度和稻草培养液的不同pH值影响草履虫的生长繁殖进行了实验研究,统计分析表明影响较为明显。稻草培养液的最适浓度为1%~2%;奶粉培养液的最适浓度为0.1%~0.2%;玉米粒培养液的最适浓度为1%~2%;稻草培养液最适pH值为7.0。     

Antigenic Relationships Among Strains of Vibrio parahaemolyticus

The antigenic relationships of 79 strains of Vibrio parahaemolyticus representing 46 assigned K-types were studied by tube agglutination. Homologous titers of 46 anti-K sera ranged from 80 to 2,560. All but three sera exhibited from one to six heterologous reactions, the majority of which gave titers of 相似文献   

Effects on Mitochondrial K Flux of pH,K Concentration,and N-Ethyl Maleimide

Based on published evidence that cation transport in mitochondria is not significantly dependent on a membrane potential, it is suggested that the process of mitochondrial cation transport may be nonelectrogenic. These experiments focused on the possibility that K⁺ flux into rat liver mitochondria may be directly coupled, via an energy-linked carrier mechanism, to OH^? influx or H⁺ efflux. The dependence of the unidirectional K⁺ influx on the external K⁺ concentration indicates involvement of a saturable mechanism. Increasing the external pH from 7.0 to 8.0 increases the apparent V_max of the K⁺ influx without significantly altering the apparent K_m for K⁺. The pH dependence is greater in the presence of N-ethyl maleimide, a known inhibitor of the mitochondrial P_i/OH^? exchange mechanism. N-Ethyl maleimide decreases the apparent V_max at pH 7.0 and increases it at pH 8.0. Evidence indicates that both N-ethyl maleimide and a high external P_i concentration may stimulate the K⁺ influx at alkaline external pH (8.0) by preventing net exchanges between endogenous P_i and external OH^?. An apparent first-order dependence of the K⁺ influx on the external OH^? concentration is observed in the presence of N-ethyl maleimide. These results are consistent with a possible role of external OH^? as a cosubstrate of the K⁺ transport mechanism.     

Introduction: Exploring the Relationships Among Aging,Ethnicity, and Family Dementia Caregiving

Culture, Medicine, and Psychiatry -     

Quantifying Relationships Among Phosphorus, Agriculture, and Lake Depth at an Inter-Regional Scale

To date, studies examining the impact of agriculture on freshwater systems have been spatially confined (that is, single drainage basin or regional level). Across regions, there are considerable differences in a number of factors, including geology, catchment morphometry, and hydrology that affect water quality. Given this heterogeneity, it is unknown whether agricultural activities have a pervasive impact on lake trophic state across large spatial scales. To address this issue, we tested whether the proportion of agricultural land in a catchment (% Agr) could explain a significant portion of the variation in lake water quality at a broad inter-regional scale. As shallow, productive systems have been shown to be particularly susceptible to eutrophication, we further investigated how lake mean depth modulates the relationship between % Agr and lake total phosphorus (TP) concentration. We applied both traditional meta-analytic techniques and more sophisticated linear mixed-effects models to a dataset of 358 temperate lakes that spanned an extensive spatial gradient (5°E to 73°W) to address these issues. With meta-analytical techniques we detected an across-study correlation between TP and % Agr of 0.53 (one-tailed P-value = 0.021). The across-study correlation coefficient between TP and mean depth was substantially lower (r = −0.38; P = 0.057). With linear mixed-effects modeling, we detected among-study variability, which arises from differences in pre-impact (background) lake trophic state and in the relationship between lake mean depth and lake TP. To our knowledge, this is the first quantitative synthesis that defines the influence of agriculture on lake water quality at such a broad spatial scale. Syntheses such as these are required to define the global relationship between agricultural land-use and water quality.     

The Function of the Na+-Driven Flagellum of Vibrio cholerae Is Determined by Osmolality and pH

Vibrio cholerae is motile by its polar flagellum, which is driven by a Na⁺-conducting motor. The stators of the motor, composed of four PomA and two PomB subunits, provide access for Na⁺ to the torque-generating unit of the motor. To characterize the Na⁺ pathway formed by the PomAB complex, we studied the influence of chloride salts (chaotropic, Na⁺, and K⁺) and pH on the motility of V. cholerae. Motility decreased at elevated pH but increased if a chaotropic chloride salt was added, which rules out a direct Na⁺ and H⁺ competition in the process of binding to the conserved PomB D23 residue. Cells expressing the PomB S26A/T or D42N variants lost motility at low Na⁺ concentrations but regained motility in the presence of 170 mM chloride. Both PomA and PomB were modified by N,N′-dicyclohexylcarbodiimide (DCCD), indicating the presence of protonated carboxyl groups in the hydrophobic regions of the two proteins. Na⁺ did not protect PomA and PomB from this modification. Our study shows that both osmolality and pH have an influence on the function of the flagellum from V. cholerae. We propose that D23, S26, and D42 of PomB are part of an ion-conducting pathway formed by the PomAB stator complex.     

Variation in Intergroup Relationships Among Species and Among and Within Local Populations of African Apes

International Journal of Primatology - Although many animals typically defend key resources from conspecifics during encounters, tolerant encounters also occur frequently in some primate species....     

Age-Related Changes of Elements and Relationships Among Elements in Human Hippocampus, Dentate Gyrus, and Fornix

To elucidate compositional changes of the limbic system with aging, the authors investigated age-related changes of elements in the hippocampus, dentate gyrus, and fornix and the relationships among elements by direct chemical analysis. After ordinary dissections at Nara Medical University were finished, the hippocampi, dentate gyri, and fornices were resected from identical cerebra of the subjects which consisted of 23 men and 23 women, ranging in age from 70 to 101 years. After ashing with nitric acid and perchloric acid, element contents were determined by inductively coupled plasma-atomic emission spectrometry. The average contents of P, Zn, and Na were significantly less in both the hippocampi and dentate gyri compared with the fornices. It was found that the Ca and Mg contents increased significantly in the hippocampus with aging; the P content increased significantly in the dentate gyrus with aging, whereas the Na content decreased in the dentate gyrus with aging; and the Mg content increased significantly in the fornix with aging. Regarding the relationships among elements, a significant direct correlation between Ca and Fe contents and an extremely significant inverse correlation between P and Zn contents were found in both the hippocampi and dentate gyri. In addition, a significant direct correlation between P and Mg contents was found in both the hippocampi and fornices. Pearson's correlation was used to examine whether there were elements with significant correlation among the hippocampus, dentate gyrus, fornix, and mammillary body. Significant correlations were found in five elements of Ca, P, Mg, Zn, and Fe except for S and Na among the hippocampus, dentate gyrus, and mammillary body with one exception. Regarding the fornix, significant correlations were found in two elements of P and Fe between the fornix and hippocampus, dentate gyrus, or mammillary body.     

Functional and Evolutionary Relationships Among the RPCH-AKH Family of Peptides

SYNOPSIS. The RPCH-AKH peptide family is a group of structurallysimilar peptides which are apparently widely distributed inarthropods, and which serve a variety of functions in differentsettings. The first three recognized members of this familywere detected and purified based on endocrine activities includingcolor change in crustaceans (RPCH) and effects on energy metabolismin insects (AKH and Compound II). The most recently identifiedfamily members, MI and Mil, were found on the basis of neuromuscularactivity as well as endocrine effects, and a combination ofhistological and physiological evidence strongly suggests thatat least some of these peptides are localized in neurons includingmotor neurons which use them as transmitters. Thus this is oneof several neuropeptide families with highly conserved structures,but diverse endocrine and neural functions. The significanceof structural similarities between family members is unclear.Fortunately the arthropod preparations in which these peptideshave been identifiedlend themselves to detailed developmental,anatomical, and physiological analysis, so there is every reasonto suppose that molecular biological and physiological investigationscurrently inprogress will shed significant light on the meaningof the phenomenon of structurally conservative peptide families.     

Interacting Effects of pH, Temperature, and Salt Concentration on Growth and Survival of Vibrio parahaemolyticus

Thermal resistance and minimal pH and temperature conditions for growth of Vibrio parahaemolyticus in artificial media containing 3 and 7% sodium chloride were studied. Growth was observed at pH 4.8 and at 5 C.     

In Vitro Susceptibility of Prototheca to pH and Salt Concentration

Prototheca sp. can assume high economic significance in the dairy industry and pose a potential risk for the public health. We investigated the in vitro susceptibility of Prototheca isolates retrieved from mastitic milk (P. zopfii and P. blaschkeae) to different pH buffers and salt concentrations using a microbroth assay adapted from the Clinical Laboratory Standards Institute guidelines. Different pH buffer solutions ranging from pH 1 to pH 12 and different sodium chloride concentrations, 4.5, 9 and 18%, were tested. P. zopfii strains presented an optimal growth between pH 5 and 9, a complete growth inhibition at pH 3, and limited growth at pH 1 and 12, whereas P. blaschkeae strains showed higher susceptibility to all pH values except for pH 3 where it demonstrated a moderate growth when compared to P. zopfii strains. When salinity was incremented, P. blaschkeae was more resistant than P. zopfii, although a reduction in growth for all strains of Prototheca was observed. This study demonstrated differences in the in vitro susceptibilities of P. zopfii and P. blaschkeae to different pH and salt concentrations and intend to be a contribution on the understanding of some of the physiologic features that can be associated with the survival of these microalgae in the environment.     

Relationships between lakewater pH and sedimentary diatoms in the Matamek Watershed,Northeastern Quebec,Canada

Twenty lakes in the Matamek and nearby watersheds were sampled in the summer of 1983 for water chemistry and surficial sediments. Thirty-two physical and chemical variables, including pH, alkalinity, cations and metal concentrations were measured on samples from the epilimnion and hypolimnion of each lake. In three lakes, two to four replicate cores were collected to estimate spatial variability of the sediment flora.All lakes were acidic (pH 4.59 to 5.80), highly colored and poorly buffered. Aluminum and magnesium concentrations reached 494 and 70 µg l^-1, respectively. The pH of the lakes appears to be declining, as indicated by a comparison of our results with those from a survey done in 1970. An empirical chemical model based on the alkalinity/sulfate ratio and the regression of pH on calcium also indicated that these lakes may be undergoing acidification.Analyses of the diatom flora of the surficial sediments showed strong dominance of 6 species that cooccurred with a large number of rare species (in all, 229 taxa were found). Variability among samples within a lake was as high as among lakes. Calculation of Nygaard's alpha index for each sample and the regression of its log-transformed value on surface pH yielded a relationship that was significantly from other published models. The regression model was applied to a down-core analysis of the diatom flora of the sediments of two lakes. Although the large confidence intervals on pH values predicted by the model obscured any evidence of pH change with sediment depth, there was a significant increase of acidophilous and a decrease of circumneutral species over time, suggesting that a change in the flora, possibly correlated with pH, is taking place.In making comparisons among lakes, the surficial-sediment flora did not provide clear evidence of a relationship with the pH of surface water. Indices computed from the surficial-sediment flora are apparently insensitive to differences in pH over a narrow range, particularly when the lakes being compared are similar chemically. Nygaard's alpha index is shown to be unduly sensitive to outliers. The currently accepted assumption of a progressive linear change in communities may be inadequate for the quantification of acidification processes. Other models, derived from catastrophe theory, may prove more fruitful.