Abnormal behavior,striatal dopamine turnover and opioid peptide gene expression in histamine‐deficient mice

Hypothalamic histaminergic neurons regulate a variety of homeostatic, metabolic and cognitive functions. Recent data have suggested a modulatory role of histamine and histamine receptors in shaping striatal activity and connected the histaminergic system to neuropsychiatric disorders. We characterized exploratory behavior and striatal neurotransmission in mice lacking the histamine producing enzyme histidine decarboxylase (Hdc). The mutant mice showed a distinct behavioral pattern during exploration of novel environment, specifically, increased frequency of rearing seated against the wall, jumping and head/body shakes. This behavioral phenotype was associated with decreased levels of striatal dopamine and serotonin and increased level of dopamine metabolite DOPAC. Gene expression levels of dynorphin and enkephalin, opioids released by medium spiny neurons of striatal direct and indirect pathways respectively, were lower in Hdc mutant mice than in control animals. A low dose of amphetamine led to similar behavioral and biochemical outcomes in both genotypes. Increased striatal dopamine turnover was observed in Hdc KO mice after treatment with dopamine precursor l ‐Dopa. Overall, our study suggests a role for striatal dopamine and opioid peptides in formation of distinct behavioral phenotype of Hdc KO mice.     

The relationship between DRD4 polymorphisms and phenotypic correlations of behaviors in the collared flycatcher

There is increasing evidence that the genetic architecture of exploration behavior includes the dopamine receptor D4 gene (DRD4). Such a link implies that the within‐individual consistency in the same behavior has a genetic basis. Behavioral consistency is also prevalent in the form of between‐individual correlation of functionally different behaviors; thus, the relationship between DRD4 polymorphism and exploration may also be manifested for other behaviors. Here, in a Hungarian population of the collared flycatcher, Ficedula albicollis, we investigate how males with distinct DRD4 genotypes differ in the consistent elements of their behavioral displays during the courtship period. In completely natural conditions, we assayed novelty avoidance, aggression and risk‐taking, traits that were previously shown repeatable over time and correlate with each other, suggesting that they could have a common mechanistic basis. We identified two single‐nucleotide polymorphisms (SNP554 and SNP764) in the exon 3 of the DRD4 gene by sequencing a subsample, then we screened 202 individuals of both sexes for these SNPs. Focusing on the genotypic variation in courting males, we found that “AC” heterozygote individuals at the SNP764 take lower risk than the most common “AA” homozygotes (the “CC” homozygotes were not represented in our subsample of males). We also found a considerable effect size for the relationship between SNP554 polymorphism and novelty avoidance. Therefore, in addition to exploration, DRD4 polymorphisms may also be associated with the regulation of behaviors that may incur fear or stress. Moreover, polymorphisms at the two SNPs were not independent indicating a potential role for genetic constraints or another functional link, which may partially explain behavioral correlations.     

新型瞬时报告载体pRSET-EGFP的构建及表达

目的：利用分子生物学技术和方法将pRSET-B质粒改建为带有绿色荧光蛋白(GFP)突变体基因(GFP-S65T)的新型瞬时表达载体pRSET-EGFP,并在E．coli．BL21中得到GFP基因的高效表达。方法：PCR法从pEGFP质粒克隆GFP-S65T cDNA并在5’末端引入KpnⅠ的位点。将扩增出来的GFP-S65T基因和pRSEY-B质粒用HindⅢ和KpnⅠ双酶切后连接构成重组质粒。用化学法把重组质粒转化到E．coli．BL21中,培养发酵液。OD540=0．4时加入IPTG诱导GFP-S65T基因转录和表达,合成绿色荧光蛋白。还对诱导条件进行了优化,发酵液OD540=0．4加入IPTG可以得到最优表达。结果：通过Ni^2 柱亲和层析,纯化得到绿色荧光蛋白,SDS-PAGE电泳检测,分子量为27kDa,与文献报道值一致。这说明Ni^2 柱能够有效的纯化表达产物。结论：成功构建了新型瞬时表达载体pRSET-EGFP,并且在E．coli．BL21中得到高效表达。     

Long-term use of televisions,balls, and mirrors as enrichment for paired and singly caged chimpanzees

The evaluation of environmental enrichment techniques for nonhuman primates over long periods of time has had mixed results. Some studies report rapid habituation to new enrichment items, while others note continued use. We have investigated the use of three different enrichments that had been available to paired and singly caged chimpanzees for several years. Twenty subjects were observed during 200 hr of scan sampling while singly caged and while pair housed. Each subject had a variety of enrichments available and their use of a television, ball, and mirror were recorded. The chimpanzees had previous exposure to all of the items: televisions had been available for a mean of 22.75 months, balls had been available for 55.9 months, and mirrors had been available for 25.9 months. The results indicated that the chimpanzees continued to use the enrichments for small amounts of time (0.27%–1.53% of the observations) even after such prolonged exposure. Television and ball use were significantly higher than mirror use. Housing condition was not a significant factor in the analyses, contrary to expectations. We concluded that several simple enrichment items may be effective in offering variety and choices to the nonhuman primate and can be one element in a comprehensive environmental enhancement plan. © 1996 Wiley-Liss, Inc.     

Resonating feathers produce courtship song

Male Club-winged Manakins, Machaeropterus deliciosus (Aves: Pipridae), produce a sustained tonal sound with specialized wing feathers. The fundamental frequency of the sound produced in nature is approximately 1500 Hz and is hypothesized to result from excitation of resonance in the feathers'' hypertrophied shafts. We used laser Doppler vibrometry to determine the resonant properties of male Club-winged Manakin''s wing feathers, as well as those of two unspecialized manakin species. The modified wing feathers exhibit a response peak near 1500 Hz, and unusually high Q-values (a measure of resonant tuning) for biological objects (Q up to 27). The unmodified wing feathers of the Club-winged Manakin do not exhibit strong resonant properties when measured in isolation. However, when measured still attached to the modified feathers (nine feathers held adjacent by an intact ligament), they resonate together as a unit near 1500 Hz, and the wing produces a second harmonic of similar or greater amplitude than the fundamental. The feathers of the control species also exhibit resonant peaks around 1500 Hz, but these are significantly weaker, the wing does not resonate as a unit and no harmonics are produced. These results lend critical support to the resonant stridulation hypothesis of sound production in M. deliciosus.     

MODERN AND HISTORICAL EVIDENCE FOR NATURAL HYBRIDIZATION BETWEEN SYMPATRIC SPECIES IN MANDARINA (PULMONATA: CAMAENIDAE)

Geographical and temporal variation in gene exchange between two endemic land snail species, Mandarina aureola and Mandarina ponderosa, was studied on Hahajima Island of the Bonin Islands. Allozyme variation in modern samples, and variation in the color and shell morphology of modern and fossil samples, suggest a complex geographical and historical pattern of hybridization. These two species occur in sympatry, and their shell morphologies and protein genotypes are markedly divergent. However, many specimens of M. aureola, collected from the middle region of the island, exhibit intermediate shell morphologies and possess marker alleles of M. ponderosa. Fossil samples of the two species strongly suggest that these intermediates were hybrids with M. ponderosa that were produced since the end of the Pleistocene. Each of these species, in addition, is subdivided into two genetically and morphologically divergent parapatric races. Interspecific hybridization appears to have produced genetical and morphological admixture among these four distinctive groups of populations. The past distribution and geographic variation of M. ponderosa can be traced in the distribution of M. ponderosa-derived genotypes in current populations of M. aureola. Temporal changes of the color pattern in the fossil populations of hybrids suggest that the traits introduced from M. ponderosa to M. aureola have been affected by natural selection and could replace traits of living species when advantageous. Moreover, these introgressed genes appeared to provide novel properties that enabled M. aureola to advance into a new environment. Relatively independent change in shell color and morphology further suggests mosaic evolution following the hybridization events. Connectively, these data reveal how hybridization events may be an important source of evolutionary novelties and make it clear that the phenomenon of reticulate evolution cannot be ignored.     

Exploratory behavior ofLasius pallitarsis ants encountering novel areas

Summary Lasius pallitarsis ants were placed in situations where they encountered unfamiliar areas and had to choose between one of two directions for further exploration. Workers advancing onto new ground apparently leave behind some chemical signature to which later ants orient. This orientation occurred under two types of experimental conditions. First, ants show a significant tendency to follow each other as they advance out from their colony into unexplored areas. The same ants transferred into an entirely novel situation, in which there is no obvious homeward direction, show similar behavior. When ants are coming from familiar ground, following tends to increase as the number of ants passing the decision point increases. However, following decreases when ants are on entirely novel ground. The results are discussed in relation to models describing foraging responses.     

Close Proximity of the Heterosexual Partner Reduces the Physiological and Behavioral Consequences of Novel-Cage Housing in Black Tufted-Ear Marmosets (Callithrix kuhli)

The present studies assessed the extent to which heterosexual pairmates could buffer marmosets (Wied's black tufted-ear marmoset,Callithrix kuhli)against stress. Six male and six female marmosets from established groups were exposed to two experimental manipulations together with a control condition. Each condition lasted a total of 4 days. For the two experimental conditions, animals were removed from the family group and housed in a novel cage for 48 h in either the presence or the absence of the heterosexual pairmate. During the 48-h novel-cage housing period and for 48 h upon reunion of the subjects with the family group, concentrations of urinary cortisol were measured in the first void sample of the day and behavioral observations were conducted. When animals were housed alone in a novel cage they exhibited significant elevations in levels of urinary cortisol after 24 and 48 h of novel-cage exposure. In contrast, when marmosets were housed in the novel cage in the presence of the pairmate, levels of urinary cortisol did not change across the 4-day period. The presence of the social partner also reduced the behavioral manifestations of exposure to novelty. Upon reunion with the family group, animals that had been housed in the novel cage alone spent significantly more time in close proximity to the pairmate than animals that had been housed with the partner. A second experiment was conducted to determine the effect that separation from the pairmate, only (independent of any effects of novelty), had on levels of cortisol. Concentrations of urinary cortisol were measured in subjects housed in the familiar home cage, but in the absence of the pairmate, over a 48-h period and compared to concentrations of excreted cortisol immediately prior to separation. Separation from the pairmate did not elevate cortisol levels when the subject was housed in the home cage, suggesting that elevated cortisol levels in animals housed alone in the novel cage were in response to novelty exposure rather than to separation from the pairmate. Since the physical presence of the heterosexual partner reduced the physiological and behavioral effects of novel-cage housing, social attachments might function as homeostatic regulators of HPA function in marmosets.