Identification and characterization of Letm1 gene in Toxoplasma gondii

Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis.Previous studies have shown that the perturbation of mitochondrial metabolism in T.gondii results in growth deficiency in host cells and lack of virulence in animals.Members of this Letm1 protein family are inner mitochondrial membrane proteins which play a role in potassium and hydrogen ion exchange.Letm1 has not been characterized in T.gondii.In this study,a potential TgLetm1 gene (TgGT1_288400) with Letm1-like protein domain coding sequence was identified in T.gondii.Indirect immunofluorescence assays suggested that TgLetm1 localized to the mitochondria in tachyzoites,as indicated by the colocalization with mitochondrial marker Mitotracker.TgLetm1 was found in the membrane fraction by western blot analysis.To investigate the role of TgLetm1 in T.gondii,we generated a tetracycline-inducible TgLetm1-knock-down mutant.The conditional deletion of TgLetm1 resulted in mitochondrial swelling.Functional studies showed that the conditional deletion of TgLetm1 resulted in growth inhibition,deficiency in invasion and replication,and lack of virulence in mice.     

Professor Ko Shimamoto （1949-2013）

Sadly, Prof. Ko Shimamoto died on September 28, 2013, aged 63. He was born in Wakayama, Japan, on October 19, 1949, received his bachelor＇s degree in Agriculture from Kyoto University in 1974 and his PhD in Genetics from the University of Wisconsin- Madison in 1980. After his postdoctoral training at the Friedrich Miescher Institute in Basel, Switzerland,     

Sex differences in morphine-induced behavioral sensitization and social behaviors in ICR mice

Gender and genetic strain are two prominent variants that influence drug abuse. Although certain sexrelated behavioral responses have been previously characterized in ICR mice, little is known about the effects of sex on morphine-induced behavioral responses in this outbred strain. Therefore, in this study, we investigated the sex differences of morphine-induced locomotion, anxiety-like and social behaviors in ICR mice. After morphine or saline exposure for four consecutive days(twice daily), increased locomotion, more time spent in the central area, as well as attenuated rearing and self-grooming behaviors were found in morphine-treated females in an open field; no differences were found in locomotion and the time spent in the central area between male and female controls. When interacting with the samesex individuals, female controls were engaged in more social investigation, following, body contacting and self-grooming behaviors than controls; morphine exposure reduced contacting and self-grooming behaviors in females; in contrast, these effects were not found in males. These results indicate that female ICR mice are more prosocial and are more susceptible to morphine exposure than males.     

microRNAs in a multicellular green alga Volvox carteri

microRNAs(miRNAs)have emerged as key components in the eukaryotic gene regulatory network.We and others have previously identified many miRNAs in a unicellular green alga,Chlamydomonas reinhardtii.To investigate whether miRNA-mediated gene regulation is a general mechanism in green algae and how miRNAs have been evolved in the green algal lineage,we examined small RNAs in Volvox carteri,a multicellular species in the same family with Chlamydomonas reinhardtii.We identified 174 miRNAs in Volvox,with many of them being highly enriched in gonidia or somatic cells.The targets of the miRNAs were predicted and many of them were subjected to miRNA-mediated cleavage in vivo,suggesting that miRNAs play regulatory roles in the biology of green algae.Our catalog of miRNAs and their targets provides a resource for further studies on the evolution,biological functions,and genomic properties of miRNAs in green algae.     

Identification and characterization of lamprey nucleolin-like gene

Nucleolin was first described in 1973 as a protein involved in ribosome biogenesis and in DNA and RNA metabolism.It is a wellknown major non-ribosomal protein in the nucleolus,and is mainly distributed in the dense fibrillar and granular regions of the nucleolus.     

Neurotrophin signaling and visceral hypersensitivity

Neurotrophin family are traditionally recognized for their nerve growth promoting function and are recently identified as crucial factors in regulating neuronal activity in the central and peripheral nervous systems. The family members including nerve growth factor （NGF）, brain-derived neurotrophic factor （BDNF）, and neurotrophin-3 （NT-3） are reported to have distinct roles in the development and maintenance of sensory phenotypes in normal states and in the modulation of sensory activity in disease. This paper highlights receptor tyrosine kinase （Trk） -mediated signal transduction by which neurotrophins regulate neuronal activity in the visceral sensory reflex pathways with emphasis on the distinct roles of NGF and BDNF signaling in physiologic and pathophysiological processes. Viscero-visceral cross-organ sensitization exists widely in human diseases. The role of neurotrophins in mediating neural cross talk and interaction in primary afferent neurons in the dorsal root ganglia （DRG） and neurotrophin signal transduction in the context of cross-organ sensitization are also discussed.     

Energy intake,oxidative stress and antioxidant in mice during lactation

Reproduction is the highest energy demand period for small mammals, during which both energy intake and expenditure are increased to cope with elevated energy requirements of offspring growth and somatic protection. Oxidative stress life history theory proposed that reactive oxygen species(ROS) were produced in direct proportion to metabolic rate, resulting in oxidative stress and damage to macromolecules. In the present study, several markers of oxidative stress and antioxidants activities were examined in brain, liver, kidneys, skeletal muscle and small intestine in non-lactating(Non-Lac) and lactating(Lac) KM mice. Uncoupling protein(ucps) gene expression was examined in brain, liver and muscle. During peak lactation, gross energy intake was 254% higher in Lac mice than in Non-Lac mice. Levels of H2O2 of Lac mice were 17.7% higher in brain(P<0.05), but 21.1%(P<0.01) and 14.5%(P<0.05) lower in liver and small intestine than that of Non-Lac mice. Malonadialdehyde(MDA) levels of Lac mice were significantly higher in brain, but lower in liver, kidneys, muscle and small intestine than that of Non-Lac mice. Activity of glutathione peroxidase(GSH-PX) was significantly decreased in brain and liver in the Lac group compared with that in the Non-Lac group. Total antioxidant capacity(TAOC) activity of Lac mice was significantly higher in muscle, but lower in kidneys than Non-Lac mice. Ucp4 and ucp5 gene expression of brain was 394% and 577% higher in Lac mice than in Non-Lac mice. These findings suggest that KM mice show tissuedependent changes in both oxidative stress and antioxidants. Activities of antioxidants may be regulated physiologically in response to the elevated ROS production in several tissues during peak lactation. Regulations of brain ucp4 and ucp5 gene expression may be involved in the prevention of oxidative damage to the tissue.     

Paramutation： A Heritable Change in Gene Expression by Allelic Interactions In Trans

Epigenetic gene regulation involves the stable propagation of gene activity states through mitotic, and sometimes even meiotic, cell divisions without changes in DNA sequence. Paramutation is an epigenetic phenomenon involving changes in gene expression that are stably transmitted through mitosis as well as meiosis. These heritable changes are mediated by in trans interactions between homologous DNA sequences on different chromosomes. During these in trans interactions, epigenetic information is transferred from one allele of a gene to another allele of the same gene, resulting in a change in gene expression. Although paramutation was initially discovered in plants, it has recently been observed in mammals as well, suggesting that the mechanisms underlying paramutation might be evolutionarily conserved. Recent findings point to a crucial role for small RNAs in the paramutation process. In mice, small RNAs appear sufficient to induce paramutation, whereas in maize, it seems not to be the only player in the process. In this review, potential mechanisms are discussed in relation to the various paramutation phenomena.     

梅根际丛枝菌根真菌三个中国新记录种

Three new Chinese records, Acaulospora paulinae, Glomus aureum, and Pacispora robigina were found in a survey of arbuscular mycorrhizal fungi associated with Prunus mume in China. They were redescribed and illustrated in accordance with Chinese materials. These specimens were stored in the Herbarium Mycologicum Academiae Sinicae (HMAS) in Beijing.