2,3,7,8-Tetrachlorodibenzo-p-dioxin in breast milk increases autistic traits of 3-year-old children in Vietnam.

Dioxin levels in the breast milk of mothers residing near a contaminated former airbase in Vietnam remain much higher than in unsprayed areas, suggesting high perinatal dioxin exposure for their infants. The present study investigated the association of perinatal dioxin exposure with autistic traits in 153 3-year-old children living in a contaminated area in Vietnam. The children were followed up from birth using the neurodevelopmental battery Bayley-III. The high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposed groups (⩾3.5 pg per g fat) showed significantly higher Autism Spectrum Rating Scale (ASRS) scores for both boys and girls than the mild-TCDD exposed groups, without differences in neurodevelopmental scores. In contrast, the high total dioxin-exposed group, indicated by polychlorinated dibenzo-p-dioxins/furans (PCDDs/Fs)--the toxic equivalents (TEQ) levels⩾17.9 pg-TEQ per g fat, had significantly lower neurodevelopmental scores than the mild-exposed group in boys, but there was no difference in the ASRS scores. The present study demonstrates a specific impact of perinatal TCDD on autistic traits in childhood, which is different from the neurotoxicity of total dioxins (PCDDs/Fs).

Diminished pheromone-induced sexual behavior in neurokinin-1 receptor deficient (TACR1(-/-)) mice.

Studies in mice with targeted deletions of tachykinin genes suggest that tachykinins and their receptors influence emotional behaviors such as aggression, depression and anxiety. Here, we investigated whether TAC1- and TAC4-encoded peptides (substance P and hemokinin-1, respectively) and the neurokinin-1 receptor (NK-1R) are involved in the modulation of sexual behaviors. Male mice deficient for the NK-1R (TACR1 (-/-)) exhibited decreased exploration of female urine in contrast to C57BL/6 control mice and mice deficient for NK-1R ligands such as TAC1 (-/-), TAC4 (-/-) and the newly generated TAC1 (-/-) /TAC4 (-/-) mice. In comparison to C57BL/6 mice, mounting frequency and duration were decreased in male TACR1 (-/-) mice, while mounting latency was increased. Decreased preference for sexual pheromones was also seen in female TACR1 (-/-) mice. Furthermore, administration of the NK-1R-antagonist L-703,606 decreased investigation of female urine by male C57BL/6 mice, suggesting an involvement of NK-1R in urine sniffing behavior. Our results provide evidence for the NK-1R in facilitating sexual approach behavior, as male TACR1 (-/-) mice exhibited blunted approach behavior toward females following the initial interaction compared with C57BL/6 mice. NK-1R signaling may therefore play an important role in pheromone-induced sexual behavior.

Single gene and gene interaction effects on fertilization and embryonic survival rates in cattle.

Decrease in fertility and conception rates is a major cause of economic loss and cow culling in dairy herds. Conception rate is the product of fertilization rate and embryonic survival rate. Identification of genetic factors that cause the death of embryos is the first step in eliminating this problem from the population and thereby increasing reproductive efficiency. A candidate pathway approach was used to identify candidate genes affecting fertilization and embryo survival rates using an in vitro fertilization experimental system. A total of 7,413 in vitro fertilizations were performed using oocytes from 504 ovaries and semen samples from 10 different bulls. Fertilization rate was calculated as the number of cleaved embryos 48 h postfertilization out of the total number of oocytes exposed to sperm. Survival rate of embryos was calculated as the number of blastocysts on d 7 of development out of the number of total embryos cultured. All ovaries were genotyped for 8 genes in the POU1F1 signaling pathway. Single-gene analysis revealed significant associations of GHR, PRLR, STAT5A, and UTMP with survival rate and of POU1F1, GHR, STAT5A, and OPN with fertilization rate. To further characterize the contribution of the entire integrated POU1F1 pathway to fertilization and early embryonic survival, a model selection procedure was applied. Comparisons among the different models showed that interactions between adjacent genes in the pathway revealed a significant contribution to the variation in fertility traits compared with other models that analyzed only bull information or only genes without interactions. Moreover, some genes that were not significant in the single-gene analysis showed significant effects in the interaction analysis. Thus, we propose that single genes as well as an entire pathway can be used in selection programs to improve reproduction performance in dairy cattle.

Hippocampal place cell activity during chasing of a moving object associated with reward in rats.

Hippocampal place cells encode location of animals in the environment. However, it remains unknown whether the hippocampal place cells encode a continuously moving object in the environment. To investigate this topic, we analyzed the place cell activity of freely moving rats when a toy car was introduced into an arena. First, in a freely moving task without the car, the rats freely navigated inside the arena to earn an intracranial stimulation (ICS) reward for each 150 cm traveled. Second, they were divided into two groups and tested using two different tasks. In the car-dependent navigation (CDN) task, the car was placed inside the arena, and the rat received ICS if it chased and came within 20 cm of the car. In the car-independent navigation (CIN) task, the rat acquired ICS rewards if it traveled 150 cm regardless of its relation to the car. Place fields remapped more frequently in the CDN than the CIN tasks. In both the CDN and CIN tasks, the place cell activity inside the place fields displayed moderate tuning to the movement parameters of the rats and car, and the distance between the car and rats. However, tuning of the place cells to movement variables of the car was more selective in the CDN than the CIN tasks, while information regarding movement variables of the car represented by the place cell activity was larger in the CDN than the CIN task. These results indicated that place cell activity within the place fields represents not only an animal's own location but also the movement variables of another moving object if that object is associated with rewards. The present results provide new evidence that place cell activity conveys relevant information in a task even if this information is derived from other moving objects.

Contribution of hippocampal place cell activity to learning and formation of goal-directed navigation in rats.

Although extensive behavioral studies have demonstrated that hippocampal lesions impair navigation toward specific places, the role of hippocampal neuronal activity in the development of efficient navigation during place learning remains unknown. The aim of the present study was to investigate how hippocampal neuronal activity changes as rats learn to navigate efficiently to acquire rewards in an open field. Rats were pre-trained in a random reward task where intracranial self-stimulation rewards were provided at random locations. Then, the rats were trained in a novel place task where they were rewarded at two specific locations as they repeatedly shuttled between them. Hippocampal neuronal activity was recorded during the course of learning of the place task. The rats learned reward sites within several sessions, and gradually developed efficient navigation strategies throughout the learning sessions. Some hippocampal neurons gradually changed spatial firing as the learning proceeded, and discharged robustly near the reward sites when efficient navigation was established. Over the learning sessions, the neuronal activity was highly correlated to formation of efficient shuttling trajectories between the reward sites. At the end of the experiment, spatial firing patterns of the hippocampal neurons were re-examined in the random reward task. The specific spatial firing patterns of the neurons were preserved if the rats navigated, as if they expected to find rewards at the previously valid locations. However, those specific spatial firing patterns were not observed in rats pursuing random trajectories. These results suggest that hippocampal neurons have a crucial role in formation of an efficient navigation.

Localization of cell division protein FtsK to the Escherichia coli septum and identification of a potential N-terminal targeting domain.

Escherichia coli cell division protein FtsK is a homolog of Bacillus subtilis SpoIIIE and appears to act late in the septation process. To determine whether FtsK localizes to the septum, we fused three N-terminal segments of FtsK to green fluorescent protein (GFP) and expressed them in E. coli cells. All three segments were sufficient to target GFP to the septum, suggesting that as little as the first 15% of the protein is a septum-targeting domain. Localized fluorescence was detectable only in cells containing a visible midcell constriction, suggesting that FtsK targeting normally occurs only at a late stage of septation. The largest two FtsK-GFP fusions were able at least partially to complement the ftsK44 mutation in trans, suggesting that the N- and C-terminal domains are functionally separable. However, overproduction of FtsK-GFP resulted in a late-septation phenotype similar to that of ftsK44, with fluorescent dots localized at the blocked septa, suggesting that high levels of the N-terminal domain may still localize but also inhibit FtsK activity. Interestingly, under these conditions fluorescence was also sometimes localized as bands at potential division sites, suggesting that FtsK-GFP is capable of targeting very early. In addition, FtsK-GFP localized to potential division sites in cephalexin-induced and ftsI mutant filaments, further supporting the idea that FtsK-GFP can target early, perhaps by recognizing FtsZ directly. This hypothesis was supported by the failure of FtsK-GFP to localize in ftsZ mutant filaments. In ftsK44 mutant filaments, FtsA and FtsZ were usually localized to potential division sites between the blocked septa. When the ftsK44 mutation was incorporated into the FtsK-GFP fusions, localization to midcell ranged between very weak and undetectable, suggesting that the FtsK44 mutant protein is defective in targeting the septum.

Interleukin-1 production in tumor cells of human melanoma surgical specimens.

To determine whether IL-1 alpha and/or IL-1 beta protein is expressed by human melanoma tumor in vivo, we first analyzed nine human melanoma cell lines and optimized the in situ detection of these proteins. Three of the melanoma cell lines stained positively for both IL-1 alpha and IL-1 beta using immunohistochemistry (IHC). THe specificity of IHC was confirmed by the ability of purified recombinant IL-1 alpha and IL-1 beta protein to abolish the staining after being adsorbed by their respective antibodies before use in IHC. The three positively staining cell lines were also the only lines to demonstrate IL-1 production by western blot analysis as well as IL-1 secretion by ELISA. Next we examined 29 surgically obtained melanoma tumor specimens (6 primary and 23 metastases) that had been formalin fixed and paraffin embedded. Using the same anti-IL-1 antibodies, 5 of 23 metastatic tumors stained positively. None of the 6 primary lesions stained for either IL-1 alpha or IL-1 beta. Comparison of staining pattern performed on serially sectioned tissue using preimmune serum and antibodies against S-100 protein, melanoma-associated antigen (HMB-45), and CD68 (kappa P1), which recognizes monocyte-macrophage cell lineage, demonstrates for the first time that IL-1 protein is produced by human melanoma tumor cells in vivo. These findings provide the basis for examination of what may be a previously unrecognized biologically distinct subset of patients.