Is maternal behavior correlated with later explorative behavior of young guinea pigs (Cavia aperea f. porcellus)?

The results of previous studies, mostly involving primates, have shown a correlation between mothering styles and later explorative behavior of the young. On the basis of our previous study on the existence of mothering styles in guinea pigs we conclude that three main components of maternal behavior are useful for these kinds of studies: locomotion, affiliative behavior, and aggressive behavior. In the present study we examined the extent to which these components were correlated with later explorative behavior of guinea-pig pups. The later explorative behavior of 48 pups from 16 mothers was measured after weaning in a series of tests designed to highlight different aspects of exploration. The results indicate that maternal behavior does not have a predominant correlation with later explorative behavior of the pups. Correlations were not found between the affiliative and aggressive behavior of the mothers and the later explorative behavior of the pups. Mothers scoring high on locomotion had pups that showed more explorative behavior than did the pups of mothers scoring low on locomotion. This correlation, however, was not linear and was significant for only one parameter. Received: 28 April 1999 / Received in revised form: 27 October 1999 / Accepted: 10 November 1999     

Pheromonal markers as indicators of parasite load: parasite-mediated behavior in salamanders (Plethodon angusticlavius)

Assessment of parasite load of conspecifics may be important during social interactions such as courtship and aggressive encounters. We used a correlational study to test whether pheromonal markers can be used to assess parasite load of conspecifics, and whether the parasite load of the pheromone receivers affected their responses. We tested the responses of parasitized and nonparasitized Ozark zigzag salamanders, Plethodon angusticlavius, to territorial markers (fecal pellets) from conspecific males. Males and females were simultaneously exposed to fecal pellets placed in front of two artificial burrows located at the opposite ends of their chambers. The treatments were (1) fecal pellet of male with low parasite load versus fecal pellet of male with high parasite load, (2) fecal pellet of male with low parasite load versus control pellet (chemical blank), and (3) fecal pellet of male with high parasite load versus control pellet. Nonparasitized females spent significantly more time near fecal pellets of males with low parasite load in test condition 1, whereas the behavior of parasitized females was not significantly different from random in any test condition. Males responded differently to treatments only in condition 3; males with low parasite loads spent significantly more time near control pellets, whereas males with high parasite loads spent significantly more time near fecal pellets of males with high parasite loads. This study demonstrates that pheromonal markers may be used for assessment of parasite load of conspecifics and that responses by both males and females may be influenced by their own level of infection. Received: 21 January 1999 / Received in revised form: 17 March 2000 / Accepted: 13 November 2000     

Application of Traditional and Phylogenetically Based Comparative Methods to Test for a Trade-off in Bacterial Growth Rate at Low versus High Substrate Concentration

Abstract It is often hypothesized that those organisms that are superior competitors for sparse resources fare poorly in competition for abundant resources, and vice versa. If there is indeed such a systematic trade-off, then this has important implications for the choice of bacterial strains in bioremediation and other applications. We studied seven bacterial strains that can grow on either 2,4-dichlorophenoxyacetate (2,4-D) or succinate as a sole source of carbon. Growth rates were measured on each substrate at both low (5 μg/ml) and high (500 μg/ml) concentrations. We used two different methods to test the significance of correlations among growth rates, a traditional method that treats each strain as an independent observation and a newer method that takes into account phylogenetic relationships between strains, thereby avoiding spurious correlations caused by a lack of statistical independence of strains. In both 2,4-D and succinate, we observed significant positive correlations between growth rates measured at high and low substrate concentrations by the traditional comparative method. No significant correlations were detected after adjusting for the phylogenetic relationships among the strains. In neither case did we observe the negative correlation expected from a trade-off between growth rates at high and low substrate levels. Received: 5 April 1999; Accepted: 8 July 1999     

An improved optical technique for monitoring plant cell concentration

 An improved optical method was developed to determine cell weight concentrations using a micro-plate reader. Light absorbance was measured by a vertical light beam, which can minimize the cell settling effect found in traditional optical measurements with a horizontal light beam. The use of well plates not only requires very small sample sizes, but also handles a large number of samples at the same time. Absorbance measurements were linearly related to cell weight over the full range of batch culture growth. Received: 4 Jannuary 1999 / Revision received: 23 March 1999 / Accepted: 14 April 1999     

Linkage disequilibrium and fingerprinting in sugar beet

It has been suggested that map information for molecular markers can be used to strengthen finterprinting analyses. The success of this strategy depends on the distribution of linkage disequilibrium over the genome. Using 451 mapped AFLP markers, we investigated the occurrence of linkage disequilibrium in nine sugar beet breeding lines. A low but significant level of linkage disequilibrium was found for unlinked markers. Only for very tigthly linked (<3 cM) markers was this level substantially higher. This implies that little is gained in utilising the map position of the markers in fingerprinting applications. Received: 25 May 1999 / Accepted: 18 Oktober 1999     

Territorial aggression, circulating levels of testosterone, and brain aromatase activity in free-living pied flycatchers

Testosterone (T) is a critical endocrine factor for the activation of many aspects of reproductive behavior in vertebrates. Castration completely eliminates the display of aggressive and sexual behaviors that are restored to intact level by a treatment with exogenous T. There is usually a tight correlation between the temporal changes in plasma T and the frequency of reproductive behaviors during the annual cycle. In contrast, individual levels of behavioral activity are often not related to plasma T concentration at the peak of the reproductive season suggesting that T is available in quantities larger than necessary to activate behavior and that other factors limit the expression of behavior. There is some indication from work in rodents that individual levels of brain aromatase activity (AA) may be a key factor that limits the expression of aggressive behavior, and in agreement with this idea, many studies indicate that estrogens produced in the brain by the aromatization of T may contribute to the activation of reproductive behavior, including aggression. We investigated here in pied flycatcher (Ficedula hypoleuca) the relationships among territorial aggression, plasma T, and brain AA at the peak of the reproductive season. In a first experiment, blood samples were collected from unpaired males holding a primary territory and, 1 or 2 days later, their aggressive behavior was quantified during standardized simulated territorial intrusions. No relationship was found between individual differences in aggressive behavior and plasma T or dihydrotestosterone levels but a significant negative correlation was observed between number of attacks and plasma corticosterone. In a second experiment, aggressive behavior was measured during a simulated territorial intrusion in 22 unpaired males holding primary territories. They were then immediately captured and AA was measured in their anterior and posterior diencephalon and in the entire telencephalon. Five males that had attracted a female (who had started egg-laying) were also studied. The paired males were less aggressive and correlatively had a lower AA in the anterior diencephalon but not in the posterior diencephalon and telencephalon than the 22 birds holding a territory before arrival of a female. In these 22 birds, a significant correlation was observed between number of attacks/min displayed during the simulated territorial intrusion and AA in the anterior diencephalon but no correlation was found between these variables in the two other brain areas. Taken together, these data indicate that the level of aggression displayed by males defending their primary territory may be limited by the activity of the preoptic aromatase, but plasma T is not playing an important role in establishing individual differences in aggression. Alternatively, it is also possible that brain AA is rapidly affected by agonistic interactions and additional work should be carried out to determine whether the correlation observed between brain AA and aggressive behavior is the result of an effect of the enzyme on behavior or vice versa. In any case, the present data show that preoptic AA can change quite rapidly during the reproductive cycle (within a few days after arrival of the female) indicating that this enzymatic activity is able to regulate rapid behavioral transitions during the reproductive cycle in this species.     

Interaction effects of corticosterone and experience on aggressive behavior in the green anole lizard

Aggressive encounters are accompanied by a release of stress hormone, and this corticosterone (CORT) secretion could influence aggressive behavior in subsequent encounters. We investigated the modulating effects of CORT on aggressive behavior in the context of a 5-day social experience in male green anole lizards. In Experiment 1, we measured plasma CORT levels in animals that were exposed for different times to aggressive males. In Experiment 2, using metyrapone, a CORT synthesis blocker, we tested whether CORT secretion in response to the aggressive stimulus plays a role in experience-dependent facilitation of aggressive behavior. We hypothesized that aggressive encounters would increase plasma CORT levels, and that blocking CORT synthesis with metyrapone treatment during the aggressive encounter would cause an animal to become more aggressive. We also tested whether blocking CORT would interfere with the influence of 5-day social experience on animals' behavior in a subsequent aggressive encounter. Animals that were exposed to another male showed higher plasma CORT levels immediately after the 10 min encounter than animals exposed to the non-social video, and this high level was maintained through day 5. Within the aggressive video groups, in Experiment 2, there was a distinctly different pattern in displays depending on drug condition: vehicle-injected animals showed gradual increases followed by decreases in aggressive behavioral responses to the video as the five days proceeded (habituation), while animals injected with metyrapone started out with high aggressive behavior and did not decrease behavioral responses at later trials (no habituation). Finally, when tested with a novel conspecific on day 6, animals previously injected with metyrapone showed no higher aggression than did animals previously injected with vehicle and exposed to the aggressive video. These results suggest that blocking CORT synthesis during the exposure to the aggressive video induced animals to remain aggressive toward the repetitive stimulus without habituating, while not becoming more aggressive than controls toward a novel challenger.     

Ethoxyresorufin O-deethylase (EROD) activity in the liver of dab (Limanda limanda L.) and flounder (Platichthys flesus L.) from the German Bight. EROD expression and tissue contamination

Ethoxyresorufin O-deethylase (EROD) activity was measured in the liver of dab (Limanda limanda) and flounder (Platichthys flesus) from the German Bight (southern North Sea) and compared with muscle and liver polychlorinated biphenyl (PCB) concentrations in an attempt to relate EROD activity to PCB body burden. In none of the different datasets (species-, tissue- or matrix-dependent) was a significant (P<0.05) correlation between PCB tissue contamination and EROD activity found. Yet EROD activity was significantly correlated with polycyclic aromatic hydrocarbons (PAH) levels (phenanthrene, fluoranthene, pyrene) in muscle tissue, indicating a possible dependence of EROD expression on other ubiquitous organic contaminants, thus making it a suitable biomarker for general pollution. Received: 14 April 1999 / Received in revised form: 10 July 1999 / Accepted: 15 July 1999     

Alcohol and aggressive behavior in men--moderating effects of oxytocin receptor gene (OXTR) polymorphisms

We explored if the disposition to react with aggression while alcohol intoxicated was moderated by polymorphic variants of the oxytocin receptor gene (OXTR). Twelve OXTR polymorphisms were genotyped in 116 Finnish men [aged 18-30, M = 22.7, standard deviation (SD) = 2.4] who were randomly assigned to an alcohol condition in which they received an alcohol dose of 0.7 g pure ethanol/kg body weight or a placebo condition. Aggressive behavior was measured using a laboratory paradigm in which it was operationalized as the level of aversive noise administered to a fictive opponent. No main effects of the polymorphisms on aggressive behavior were found after controlling for multiple testing. The interactive effects between alcohol and two of the OXTR polymorphisms (rs4564970 and rs1488467) on aggressive behavior were nominally significant and remained significant for the rs4564970 when controlled for multiple tests. To the best of our knowledge, this is the first experimental study suggesting interactive effects of specific genetic variants and alcohol on aggressive behavior in humans.     

Oxygen-dependent xylitol metabolism in Pichia stipitis

Pichia stipitis CBS 6054 was cultivated in chemostat cultures under aerobic and oxygen-limited conditions with xylitol alone, a mixture of xylitol and glucose and a mixture of xylitol and xylose. Xylitol metabolism was strictly respiratory and no ethanol was formed. Simultaneous feeding of xylitol and glucose and xylitol and xylose to oxygen-limited xylitol-pregrown cells resulted in ethanol formation. In vitro both pyruvate decarboxylase activity and alcohol dehydrogenase activity were present in cells metabolising xylitol under oxygen-limited conditions; however, this did not result in ethanol formation. Glucose, xylose and xylitol utilisation, respectively, were compared under anaerobic conditions with regard to growth rate, carbon source and oxygenation level during pre-cultivation. Irrespective of pre-growth conditions, xylitol was not metabolised under anaerobic conditions, whereas ethanol was formed from both xylose and glucose. Anaerobic xylose utilisation required induction of a xylose-utilising metabolic pathway during pre-cultivation. Received: 23 February 1999 / Received last revision: 20 July 1999 / Accepted: 1 August 1999     

Meteorological factors affecting daily urticaceae pollen counts in southwest Spain

The influence of meteorological factors on daily Urticaceae pollen counts were studied in Córdoba (southwest Spain) in 1996 and 1997. The daily Urticaceae pollen concentrations were obtained by using a Hirst-type volumetric sampler, and meteorological data were obtained from the Córdoba airport, located near the sampling site. The highest correlation between pollen concentration and meteorological parameters was obtained during non-rainy seasons. Temperature was found to be the most important meteorological parameter influencing pollen counts in spring, as temperature is the main reason for the increase of pollen concentration in the atmosphere. In autumn, humidity was another important parameter influencing pollen counts. Rain, however, did not appear to be significant. The influence of the pollen concentration of the 2 previous days and the pollen concentration of the previous day has been studied. During periods with low precipitation, the pollen concentration of the previous day was a useful predictor of Urticaceae pollen concentrations for the following day. Received: 4 January 1999 / Revised: 26 July 1999 / Accepted: 6 September 1999     

On-line monitoring of growth of Escherichia coli in batch cultures by bioluminescence

Bioluminescence was used to monitor growth of Escherichia coli in batch cultures on-line. Light emission of a strain engineered for constitutive bioluminescence was monitored with a simple set-up consisting of a photodiode, a photodetector amplifier and a recorder. Bioluminescence and colony forming units (CFU) of the cultures increased and decreased proportionally and were correlated during every growth phase at temperatures between 28 °C and 40 °C. Up to the late log (deceleration) phase, both light emission and CFU increased rapidly. Beyond the stationary phase these characteristics decreased very slowly at lower temperatures, while at higher ones they declined more rapidly. Towards the end of the cultivation, light emission of the cultures dropped to undetectable levels, even though CFU were recovered. This was particularly marked at lower temperatures where non-luminescent cultures retained very high CFU. This indicates that the actual metabolism of cells in a culture can be at a very low level or completely shut down, yet cells retain their capability to be culturable. The on-line technology described here has a number of potential uses in the laboratory and industry. Received: 30 September 1999 / Received revision: 29 November 1999 / Accepted: 3 December 1999     

Improvement of mechanical and biological properties of freeze-dried denitrifying alginate beads by using starch as a filler and carbon source

Freeze-dried, alginate-based beads, used for the immobilization of a denitrifying bacterium (Pseudomonas sp.), were filled with different concentrations (10%, 20%, 30% and 40%, w/w) of granular starch. The beads were incubated under denitrifying conditions in laboratory-scale, flow-through columns and monitored for changes in their physical and denitrifying properties. Freeze-dried beads containing high concentrations of starch were found to have better mechanical and denitrifying properties than beads containing low concentrations of this filler. Nitrate removal by the beads was found to be correlated with their starch content. Nitrite accumulation, as a result of incomplete denitrification, increased with the decrease in starch content of the beads. Nitrite in the outlet of the columns was measured in all types of beads during the initial phase of incubation but was undetectable, with the exception of beads with the lowest starch content, at later stages of incubation. Received: 9 November 1998 / Received revision: 3 February 1999 / Accepted: 5 February 1999     

Brief communication: Captive gorillas are right‐handed for bimanual feeding

Predominance of right‐handedness has historically been considered as a hallmark of human evolution. Whether nonhuman primates exhibit population‐level manual bias remains a controversial topic. Here, we investigated the hypothesis that bimanual coordinated activities may be a key‐behavior in our ancestors for the emergence and evolution of human population‐level right‐handedness. To this end, we collected data on hand preferences in 35 captive gorillas (Gorilla gorilla) during simple unimanual reaching and for bimanual coordinated feeding. Unimanual reaching consisted of grasping food on the ground, while bimanual feeding consisted of using one hand for holding a food and processing the food item by the opposite hand. No population‐level manual bias was found for unimanual actions but, in contrast, gorillas exhibited a significant population‐level right‐handedness for the bimanual actions. Moreover, the degree of right‐handedness for bimanual feeding exceeds any other known reports of hand use in primates, suggesting that lateralization for bimanual feeding is robust in captive gorillas. The collective evidence is discussed in the context of potential continuity of handedness between human and nonhuman primates. Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Aggression control in a bachelor herd of fringe‐eared oryx (Oryx gazella callotis), with melengestrol acetate: Behavioral and endocrine observations

Aggression control is becoming an important component in the management of animals in captivity, but rigorous quantification of aggressive behavior has heretofore been lacking. This study was done to assess the ability of melengestrol acetate (MGA) given with feed (1.54 mg/kg) to control aggression in a bachelor group of fringe‐eared oryx (Oryx gazella callotis). Systematic behavioral observations were conducted and fecal androgen content was measured for 42 and 90 days, respectively, before treatment, and during the 42 days of treatment. There was a significant reduction in concentrations of fecal androgen from 153 ± 6.0 to 95 ± 4.5 ng/g (T₆₆ = 7, P < 0.0001). This reduction in androgen excretion was apparent after the first week of treatment. There was measurable MGA excreted in the feces during treatment. Although treatment did not arrest all aggressive behaviors among animals, the decline in androgens and increase in MGA was accompanied by a significant reduction in several measures of agonistic behavior. Posturing, aggressive contact, pursuit, and submission occurred significantly less frequently after treatment, and there was also a reduction in fighting‐intention movements. Thus, both ritualized and nonritualized aspects of aggression were affected. Reductions in hormones and aggressive behaviors coincided temporally, suggestive of a potential causal relationship. Consistent with this hypothesis is a strong positive correlation between fecal androgen and total aggressive acts. This effect was not the result of a single behavioral element but occurred across several categories of agonistic behavior. Zoo Biol 20:375–388, 2001. © 2001 Wiley‐Liss, Inc.     

A new methodology for plant cell viability assessment using intracellular esterase activity

 A plant cell suspension culture of Alfalfa (Medicago sativa L.) was grown in a bioreactor using a batch procedure. The cytoplasmic esterase activity (EC 3.1) was extracted from the cells and measured during cultivation using fluorescein diacetate as the fluorogenic substrate. This enzymatic activity was conclusively found to be correlated to cell viability assessed with the membrane integrity test using the trypan blue dye. This new viability determination method is convenient, simple and can be reproduced because: (1) the difficult step of counting the cells when using the trypan blue exclusion method is avoided and (2) the esterase activity level per viable cell constituted of numerous enzymes depends on cell viability but is independent of cellular metabolism. Received: 28 January 1999 / Accepted: 1 April 1999     

Handedness in captive bonobos (Pan paniscus)

Species level right-handedness is often considered to be unique to humans. Handedness is held to be interrelated to our language ability and has been used as a means of tracing the evolution of language. Here we examine handedness in 3 captive groups of bonobos (Pan paniscus) comprising 22 individuals. We found no evidence for species level handedness. Conclusions that can be drawn from these findings are: (1) species level handedness evolved after the divergence of the Pan and Homo lineages; (2) inconsistent preferences may represent precursors to human handedness, and (3) Pan may have language abilities but these cannot be measured using handedness.     

Intra- and interspecific cohabitation of scorpions in the field and the effect of density, food, and shelter on their interactions

Scorpion cohabitation was studied qualitatively and quantitatively for several years in the field and in controlled experimental conditions in the laboratory. In the field, several cases were recorded of scorpions sharing the same shelter, either intra- or interspecifically. Intraspecific cohabitation was more prevalent than interspecific cohabitation. Among the five scorpion species studied here, Compsobuthus werneri judaicus shows the highest degree of sociality and aggregates both intra- and interspecifically. Leiurus quinquestriatus was never observed to cohabit interspecifically. Both Buthotus judaicus and C. werneri judaicus shared shelters with other scorpions more frequently during the wet season, whereas Nebo hierichonticus and Scorpio maurus fuscus cohabitated more often during the dry season. Under controlled laboratory conditions, density and availability of either food or shelter appear to be significant in facilitating cohabitation, even in the more aggressive species. Received: April 28, 1999 / Accepted: July 30, 1999     

黑线仓鼠殴斗行为模式及其与生理状态的关系

本文以分布于鲁西南山区的黑线仓鼠雄体为对象,通过测定重复遭遇战(repeated encounters)对黑线仓
鼠体重、生理指标等参数的作用,以期阐明社群冲突(social conflict)对黑线仓鼠生理状态的影响。研究结果表
明:在4 周的重复遭遇战过程中,参与冲突个体的体重增长率略有降低,但未达到显著水平;粪便肾上腺皮质
激素(GCs)含量呈现波动性变化,在整个遭遇战过程中,优势个体与从属个体的GCs 含量交替显著升高,与
冲突时间及个体社群地位均有关;优势个体保持较高的睾酮水平,利于其增强攻击行为和获得优势地位;从属
组雄体的肾上腺显著增大,但生殖腺间差异不显著;HPA 轴对HPG 轴具有显著的抑制效应,肾上腺分泌的皮质
醇可显著抑制个体的睾酮分泌,二者呈显著的负相关关系。这些数据表明,黑线仓鼠雄体可通过斗殴行为建立
明确的优势- 从属关系,睾酮可促进个体优势地位的形成并受到肾上腺皮质醇抑制;HPA 轴对HPG 轴的抑制未
能在器官指数方面得到证实。从属个体受到胁迫,对优势雄性黑线仓鼠野外生存和繁殖有重要意义。     

Biocompatible alginate from freshly collected Laminaria pallida for implantation

A simple procedure is described for the extraction and purification of alginate from the inner stipes of the kelp Laminaria pallida. Alginate yield was about 10–15% of the dry mass, with a 70:30 mannuronic/ guluronic acid ratio. Analysis of the purified alginate revealed a low polyphenol content while proteins were below detection level. The purified alginate was highly viscous, with 10–15 mPa s and 281 mPa s for a 0.1% and 0.5% solution, respectively, indicating a very high molecular mass (larger than 250 kDa). Bead formation occurred in the presence of divalent cations, but also in the presence of artificial serum (FCSIII) without added divalent cations. The biocompatibility of the alginate was tested with the in vitro mice lymphocyte test as well as by implantation of Ba²⁺ cross-linked beads beneath the kidney capsule of BB/OK rats. There was no evidence for significant mitogenic activity or fibrotic reaction. Biocompatibility of the alginate was also demonstrated by the encapsulation of human chondrocytes into Ca²⁺ cross-linked alginate beads. Immobilized chondrocytes grew and remained functional (i.e. they produced collagen). Received: 14 June 1999 / Received revision: 6 September 1999 / Accepted: 10 September 1999