Preweaning enrichment has no lasting effects on adult hippocampal neurogenesis in four-month-old mice

Since both living in an enriched environment and physical activity stimulate hippocampal neurogenesis in adult mice, we endeavored to examine whether preweaning enrichment, a sensory enrichment paradigm with very limited physical activity, had similar effects on neurogenesis later in life. Mice were removed from the dams for periods of increasing length from postnatal day 7 to 21, and exposed to a variety of sensory stimuli. At the age of 4 months, significant differences could be found between previously enriched and non-enriched animals when spontaneous activity was monitored. Enriched mice moved longer distances, and spent more time in a defined center zone of the open field. Adult neurogenesis was examined by labeling proliferating cells in the dentate gyrus with bromodeoxyuridine (BrdU). Cell proliferation, survival of the newborn cells, and net neurogenesis were similar in both groups. Volumetric measurements and stereological assessment of total granule cell counts revealed no difference in size of the dentate gyrus between both groups. Thus, in contrast to postweaning enrichment, preweaning enrichment had no lasting measurable effect on adult neurogenesis. One of the parameters responsible for this effect might be the lack of physical activity in preweaning enrichment. As physical activity is an integral part of postweaning enrichment, it might be a necessary factor to elicit a neurogenic response to environmental stimuli. The result could also imply that baseline adult hippocampal neurogenesis is independent of the changes induced by preweaning enrichment and might not contribute to the sustained types of plasticity seen in enriched animals.     

First finding of Dirofilaria repens in a natural population of Aedes albopictus

The invasive mosquito Aedes albopictus (Skuse) (Diptera: Culicidae) has become widespread in Italy during the past decade. Also Italy has foci of canine filariasis caused by Dirofilaria (Spirurida: Onchocercidae), due to subcutaneous D. repens Railliet & Henry as well as the dog heartworm D. immitis (Leidy) transmitted by various vector mosquitoes (Diptera: Culicidae). In 2002, at Fiumicino, west of Rome (Lazio Region), 17% of dogs were found to have D. repens microfilariae in peripheral blood. To evaluate the role of Ae. albopictus as a vector of Dirofilaria in this area, female mosquitoes were collected daily, June-October 2002, landing on dog or human bait in a rural house at Focene. Mosquitoes were maintained at 27 degrees C and 70% RH for 6 days, to allow development or purging of filaria larvae, then identified and frozen for subsequent molecular assay with filaria-specific ribosomal S2-S16 primers. To distinguish specimens harbouring infective L3 Dirofilaria larvae, DNA was extracted separately from the mosquito abdomen and head-thorax. Dirofilaria species were identified by sequencing, confirmed by polymerase chain reaction of positive specimens using primers specific for D. immitis and D. repens. Dirofilaria DNA was detected in 3/154 (2%) of Ae. albopictus females examined: D. repens DNA in head-thorax and abdomen of one collected 27th July; D. immitis in the abdomen of one collected 24th September; DNA of both D. immitis and D. repens in the head-thorax of one collected 11th October 2002. Thus Ae. albopictus is a potential vector of both Dirofilarias in Italy, representing risks for veterinary and human health.     

Effects of Neonatal Melatonin Administration on the Extra-Hypothalamic Regions in Rat Brains: Effects on the Serotonergic System

The effects of 100g melatonin injection at postnatal day 5 (PD 5) on the development of the central serotonergic systems in male and female rats were investigated. The contents of serotonin (5-HT) and 5-hydroxy-3-indolacetic acid (5-HIAA) were measured in several extra-hypothalamic regions at 3, 10 and 42 weeks of age. The neonatal melatonin administration increased both 5-HT and 5-HIAA levels in the striatum throughout the examined period. In the hippocampus, an increase in 5-HIAA contents by neonatal melatonin administration was found at 3 weeks but not 10 or 42 weeks of age. There were no significant differences in the effects of melatonin between male and female rats. These results indicated that exogenous melatonin administration during the early neonatal period influenced the development of the serotonergic systems in extrahypothalamic regions including the hippocampus and the striatum.     

Disruption of the epilepsy KCNQ2 gene results in neural hyperexcitability

Benign familial neonatal convulsion (BFNC) is a common idiopathic epilepsy with autosomal dominant inheritance. Recently, two novel voltage-dependent potassium channel genes, KCNQ2 and KCNQ3, were identified by positional cloning as being responsible for BFNC. Heterotetramers of the products of these genes form M-channels and regulate the threshold of electrical excitability of neurons. We disrupted the mouse KCNQ2 gene via gene targeting to study the relationship between KCNQ2 and epilepsy. Homozygous pups (KCNQ2 -/-) died within a few hours after birth owing to pulmonary atelectasis that was not due to the status of epileptic seizures, although their development was morphologically normal. Heterozygous mice had decreased expression of KCNQ2 and showed hypersensitivity to pentylenetetrazole, an inducer of seizure. These data indicate that the decreased expression of KCNQ2 might cause a hyperexcitability of the CNS, which accounts for the mechanism of BFNC.     

Potassium ion channels and human disease: phenotypes to drug targets?

A significant difficulty faced by the pharmaceutical industry is the initial identification and selection of macromolecular targets upon which de novo drug discovery programs can be initiated. A drug target should have several characteristics: known biological function; robust assay systems for in vitro characterization and high-throughput screening; and be specifically modified by and accessible to small molecular weight compounds in vivo. Ion channels have many of these attributes and can be viewed as suitable targets for small molecule drugs. Potassium (K⁺) ion channels form a large and diverse gene family responsible for critical functions in numerous cell types, tissues and organs. Recent discoveries, facilitated by genomics technologies combined with advanced biophysical characterization methods, have identified novel K⁺ channels that are involved in important physiologic processes, or mutated in human inherited disease. These findings, coupled with a rapidly growing body of information regarding modulatory channel subunits and high resolution channel structures, are providing the critical information necessary for validation of K⁺ channels as drug targets.     

Ingestion of Pythium spp. by larvae of the fungus gnat Bradysia impatiens (Diptera:Sciaridae)

Mycelium, oospores and zoospore cysts of Pythium spp. were fed to larvae of the fungus gnat Bradysia impatiens. The fungal structures were all ingested and provided a complete nutritional source for the insect's development from egg to adult. Mycelium seemed the major source of food as only empty fragments were found either in the digestive tract or in larval faeces. Oospores appeared intact and were viable both during passage through the tract and when expelled. Germination of oospores was normal. Most encysted zoospores also survived passage through the gut, although some appeared damaged. After transferring recently-fed larvae to a new food source, oospores were still detected in the digestive tract 48 h later. These results show that the larval stage of B. impatiens may serve as an important vector for Pythium spp.     

剪枝象有效学名的厘清及常见种的鉴别

剪枝象属Cyllorhynchites Voss隶属于齿颚象科Rhynchitidae齿颚象亚科Rhynchitinae齿颚象族Rhynchitini,但其属名在国内外使用较为混乱。此外,该属的常见种类栗实剪枝象Cyllorhynchites cumulatus Voss与橡实剪枝象C.ursulus Roelofs等常被误认为隶属于同族的Mecorhis或Mechoris属。通过查阅相关文献和我国多地所采集的标本,本文旨在厘清剪枝象的有效学名,并对栗实剪枝象和橡实剪枝象的形态和生态特征进行了补充,以便提供更准确的鉴别特征。结果如下:(1)剪枝象属拉丁学名为Cyllorhynchites Voss,而非Mecorhis Billberg或Mechoris。栗实剪枝象与橡实剪枝象的中文学名以寄主命名。(2)栗实剪枝象成虫身体蓝黑色,鞘翅上的白色短柔毛稀疏且行纹明显。幼虫体长6.0-9.0 mm,触角感觉器长矛状;额背面的刚毛仅有2对,标记为fs4,fs5;头盖背面无刚毛;上唇及唇基较窄。分布于黄河以南,主要以栗属植物为寄主。在安徽金寨,栗实剪枝象的羽化期在5月底-6月底,成虫羽化后即可交配、产卵,产卵期和剪枝期在6月-7月上旬。橡实剪枝象成虫身体黑褐色,但足为褐色。鞘翅上的黄色短柔毛较密且行纹不明显。幼虫体长8.0-10.0 mm,触角感觉器长圆锥状;额背面的刚毛仅有1对,标记为fs5;头盖背面的刚毛仅有1对,标记为des5;上唇及唇基较宽。广布中国南北和日本、朝鲜半岛,以栎属和青冈属植物为寄主。在四川都江堰,橡实剪枝象的羽化期在6月-7月。由于橡子尚未发育,其成虫羽化后需经历较长的营养补充期,产卵期和剪枝期在8月中旬-9月底。本研究澄清了过去关于剪枝象属的分类归属,并对两种常见剪枝象的形态和生态特征进行了深入比较,为生产上准确鉴别这些剪枝象种类提供参考。     

Albumin-deficient mouse models for studying metabolism of human albumin and pharmacokinetics of albumin-based drugs

Serum albumin is the major determinant of blood colloidal osmotic pressure acting as a depot and distributor of compounds including drugs. In humans, serum albumin exhibits an unusually long half-life mainly due to protection from catabolism by neonatal Fc receptor (FcRn)-mediated recycling. These properties make albumin an attractive courier of therapeutically-active compounds. However, pharmaceutical research and development of albumin-based therapeutics has been hampered by the lack of appropriate preclinical animal models. To overcome this, we developed and describe the first mouse with a genetic deficiency in albumin and its incorporation into an existing humanized FcRn mouse model, B6.Cg-Fcgrt^tm1Dcr Tg(FCGRT)32Dcr/DcrJ (Tg32). Albumin-deficient strains (Alb^-/-) were created by TALEN-mediated disruption of the albumin (Alb) gene directly in fertilized oocytes derived from Tg32 mice and its non-transgenic background control, C57BL/6J (B6). The resulting Alb^-/- strains are analbuminemic but healthy. Intravenous administration of human albumin to Tg32-Alb^-/- mFcRn^-/- hFcRn^Tg/Tg) mice results in a remarkably extended human albumin serum half-life of ∼24 days, comparable to that found in humans, and in contrast to half-lives of 2.6–5.8 d observed in B6, B6-Alb^-/- and Tg32 strains. This striking increase can be explained by the absence of competing endogenous mouse albumin and the presence of an active human FcRn. These novel albumin-deficient models provide unique tools for investigating the biology and pathobiology of serum albumin and are a more appropriate rodent surrogates for evaluating human serum albumin pharmacokinetics and albumin-based compounds.     

Cephalodiscus reproductive biology (Pterobranchia,Hemichordata)

Sexually mature adults and embryos and larvae of Cephalodiscus nigrescens and C. gracilis were studied by light and electron microscopy. Contrary to claims in the literature, individual coenecial cavities are inhabited by colonies of up to 15 joined zooids and not by single individuals, which is important for the interpretation of the mode of life of the related fossil group the graptolites. Some aspects of the reproductive apparatus and reproduction in Cephalodiscus are reported. The ultrastructure of the spermatozoon is described for the first time. Coelom formation is by schizocoely. The structure of the larva at several developmental stages is illustrated. Not all fertilised eggs are destined to become motile larvae and some develop into zooids omitting the motile stage. The lumen of the oviduct is much larger than previously supposed. Spermatozoa are shed into the cavity of the coenecium. It is proposed that fertilisation takes place within the coenecium. The ultrastructure of the enigmatic black ‘Comma Body’ is described and a reproductive function is proposed. Budding takes place from a base common to several zooids. This base probably also serves as an attachment foot. Large masses of yolk have been discovered within the coelom of some zooids and muscle stalks. It is inconceivable that a colony of Cephalodiscus nigrescens could survive unless it spent most of its life outside the coenecium.     

Telocytes accompanying cardiomyocyte in primary culture: two- and three-dimensional culture environment

Recently, the presence of telocytes was demonstrated in human and mammalian tissues and organs (digestive and extra-digestive organs, genitourinary organs, heart, placenta, lungs, pleura, striated muscle). Noteworthy, telocytes seem to play a significant role in the normal function and regeneration of myocardium. By cultures of telocytes in two- and three-dimensional environment we aimed to study the typical morphological features as well as functionality of telocytes, which will provide important support to understand their in vivo roles. Neonatal rat cardiomyocytes were isolated and cultured as seeding cells in vitro in two-dimensional environment. Furthermore, engineered myocardium tissue was constructed from isolated cells in three-dimensional collagen/Matrigel scaffolds. The identification of telocytes was performed by using histological and immunohistochemical methods. The results showed that typical telocytes are distributed among cardiomyocytes, connecting them by long telopodes. Telocytes have a typical fusiform cell body with two or three long moniliform telopodes, as main characteristics. The vital methylene blue staining showed the existence of telocytes in primary culture. Immunohistochemistry demonstrated that some c-kit or CD34 immuno-positive cells in engineered heart tissue had the morphology of telocytes, with a typical fusiform cell body and long moniliform telopodes. Also, a significant number of vimentin+ telocytes were present within engineered heart tissue. We suggest that the model of three-dimensional engineered heart tissue could be useful for the ongoing research on the functional relationships of telocytes with cardiomyocytes. Because the heart has the necessary potential of changing the muscle and non-muscle cells during the lifetime, telocytes might play an active role in the heart regeneration process. Moreover, telocytes might be a useful tool for cardiac tissue engineering.