MicroRNA in cell differentiation and development

The regulation of gene expression by microRNAs (miRNAs) is a recently discovered pattern of gene regulation in animals and plants. MiRNAs have been implicated in various aspects of animal development and cell differentiation, such as early embryonic development, neuronal development, muscle development, and lymphocyte development, by the analysis of genetic deletions of individual miRNAs in mammals. These studies show that miRNAs are key regulators in animal development and are potential causes of human diseases. Here we review some recent discoveries about the functions of miRNAs in cell differentiation and development. Supported by National Key Basic Research and Development Program of China (Grant No. 2005CB724602) and Knowledge Innovation Project of the Chinese Academy of Sciences (Grant Nos. KSCX2-YW-R-096, KSCX1-YW-R-64)     

In vitro cultivation of Fasciola hepatica metacercariae and of partially developed flukes recovered from mice

Attempts were made to culture the metacercariae of Fasciola hepatica under a wide variety of conditions. Of the media tested, the most successful was NCTC 135 plus 50% heat inactivated chick serum and sheep red blood cells at 37°–38°C. In this medium, somatic development of newly excysted juveniles was similar to that of flukes recovered from the liver of a mouse 11 days post-infection. There was, however, no corresponding development of the genital rudiment. Various supplements, such as liver extract, bile, yeast extract, embryo extract, egg products, monolayer cells and diphasic media were tested, but none enhanced development. The effects of various physical parameters on growth and development in vitro were examined. Cultured metacercariae appeared to be in a state of ‘suspended animation’; when injected intraperitoneally into mice they developed into egg-producing adults. Flukes recovered from the abdomen and liver of mice continued their somatic growth in vitro but their genitalia failed to develop further.     

Conserving global biological diversity by encouraging alternative development paths: can development coexist with diversity?

The conservation of biological diversity concerns the management of the development process, not only at the national but also at the global level. Individual countries have made their development choices independently but relatedly, too often following the precise form of the choices of other countries preceding them in the development process. Development via imitation is pursuing the form, rather than the substance of a successful development strategy. Countries should instead be developing upon a base of assets that provides them with a relatively unique set of goods and services to place upon global markets. When the first countries developed, this criterion indicated that they should convert their countries to new forms of production; when the last countries are developing, relatively unique goods and services flow from their lands as they stand. What is required is the development of global institutions that encourage countries to see that their best development opportunities lie down these alternative development pathways, based upon their already-existing but relatively unique national assets.     

Characterization of Sgo1 expression in developing and adult mouse

SGO1 has been characterized in its function in correct cell division and its role in centrosome cohesion in the nucleus. However, its organ-specific maturation-related expression pattern in vivo remains largely uncharacterized. Here, we show clear SGO1 expression in post-developmental neuronal cells and cytoplasmic localisation in nucleated cells with a transgenic mice model and immunohistochemistry of wild type mice. We demonstrate extranuclear expression of Sgo1 in the developing heart and gut, which have been shown to be dysregulated in humans with homozygous SGO1 mutation. Additionally, we show Sgo1 expression in select population of retinal cells in developing and post-developmental retina. Our expression analysis strongly suggests that the function of SGO1 goes beyond its well characterized role in cell division.     

MicroRNA与动物发育

MicroRNA(miRNA)是一类约22nt大小的内源性非编码RNA,它们通过剪切靶基因的转录产物或者抑制转录产物的翻译从而起到转录后调控靶基因表达的作用。在动物体内,通过基因敲除等方法所进行的大量研究表明了miRNA参与了胚胎早期发育、脑及神经发育、心脏发育、肌肉及骨骼发育等动物发育的各个方面。miRNA是动物发生发育过程中重要的调控因子。主要介绍了近年来miRNA在动物生长发育过程中的研究进展。     

A requirement for Fgfr2 in middle ear development

The skeletal structure of the mammalian middle ear, which is composed of three endochondral ossicles suspended within a membranous air‐filled capsule, plays a critical role in conducting sound. Gene mutations that alter skeletal development in the middle ear result in auditory impairment. Mutations in fibroblast growth factor receptor 2 (FGFR2), an important regulator of endochondral and intramembranous bone formation, cause a spectrum of congenital skeletal disorders featuring conductive hearing loss. Although the middle ear malformations in multiple FGFR2 gain‐of‐function disorders are clinically characterized, those in the FGFR2 loss‐of‐function disorder lacrimo‐auriculo‐dento‐digital (LADD) syndrome are relatively undescribed. To better understand conductive hearing loss in LADD, we examined the middle ear skeleton of mice with conditional loss of Fgfr2. We find that decreased auditory function in Fgfr2 mutant mice correlates with hypoplasia of the auditory bulla and ectopic bone growth at sites of tendon/ligament attachment. We show that ectopic bone associated with the intra‐articular ligaments of the incudomalleal joint is derived from Scx‐expressing cells and preceded by decreased expression of the joint progenitor marker Gdf5. Together, these results identify a role for Fgfr2 in development of the middle ear skeletal tissues and suggest potential causes for conductive hearing loss in LADD syndrome.     

Perinatal dental development in the chimpanzee (Pan troglodytes)

The synthesis of both ontogenetic and phylogenetic data should provide the ideal explanation of morphologic variation, but for the primate dentition, this has not yet occurred. Information concerning growth and development of primate teeth is lacking, in part because of the paucity of specimens. We have therefore examined the deciduous second molars (dm2) and tooth buds of the permanent first molar (M1) of 12 chimpanzees (Pan troglodytes), aged 6.5 months of gestation to 4 postnatal months. The ordering of cusp calcification was identical to that of other primates. By regression analysis, correlations of mesial and distal widths with buccal, lingual, and mesiodistal lengths were low, most probably because of decreased rates of change (slopes) and the relatively small sample size. Correlations were, however, greater for mandibular than for maxillary dentition and higher for age than for body weight; for both the dm2 and M1, distal moieties increased faster and were more highly correlated with other dental variables and age than were mesial ones. Comparison with data from humans revealed both differences and similarities in the absolute size and growth rate of dental moieties during the perinatal period. As the reasons for ontogenetic variation become understood for individuals, species, and higher taxa, the phylogenetic implications of differential growth should become clearer as well.     

The role of oxygen availability in the embryonation of Heterakis gallinarum eggs.

The importance of oxygen availability in the embryonation of the infective egg stages of the gastrointestinal nematode parasite Heterakis gallinarum was studied in the laboratory. Unembryonated H. gallinarum eggs were kept under either aerobic conditions by gassing with oxygen, or anaerobic conditions by gassing with the inert gas nitrogen, under a range of constant temperatures. Oxygenated eggs embryonated at a rate influenced by temperature. Conversely, eggs treated with nitrogen showed no embryonation although when these eggs were transferred from nitrogen to oxygen gas after 60 days of treatment, embryonation occurred. This demonstrated that oxygen is an essential requirement for H. gallinarum egg development, although undeveloped eggs remain viable, even after 60 days in low oxygen conditions. The effects of climate on the biology of free-living stages studied under constant laboratory conditions cannot be applied directly to the field where climatic factors exhibit daily cycles. The effect of fluctuating temperature on development was investigated by including an additional temperature group in which H. gallinarum eggs were kept under daily temperature cycles between 12 and 22°C. Cycles caused eggs to develop significantly earlier than those in the constant mean cycle temperature, 17°C, but significantly slower than those in constant 22°C suggesting that daily temperature cycles had an accelerating effect on H. gallinarum egg embryonation but did not accelerate to the higher temperature. These results suggest that daily fluctuations in temperature influence development of the free-living stages and so development cannot be accurately predicted on the basis of constant temperature culture.     

Patterns in stage duration and development among marine and freshwater calanoid and cyclopoid copepods: a review of rules,physiological constraints,and evolutionary significance

Studies of development time of marine and freshwater copepods have taken separate tracks. Most studies on marine copepods report development time of each individual development stage, whereas studies on freshwater copepods report only development time, from egg to nauplius and nauplius to adult. This bias allows comparison of total development time but prevents detailed comparisons of patterns in stage-specific developmental schedules. With respect to egg to adult development time, three general relationships are known: developmental rates are dependent upon temperature and food concentration but independent of terminal body size; freshwater calanoids develop significantly slower than marine calanoids; freshwater cyclopoids develop at the same rate as marine calanoids. Two rules describe stage-specific developmental rates: the equiproportional rule and the isochronal rule. The first rule states that the duration of a given life history stage is a constant proportion of the embryonic development time; the second rule states that the time spent in each stage is the same for all stages. This review focuses on the second rule. From the 80+ published studies of copepod stage-specific developmental times, no species follows the isochronal rule strictly: Acartia spp. come closest with isochronal development from third nauplius (N3) to fourth copepodite (C4). The only pattern followed by all species is rapid development of the first and/or second naupliar stages, slow development of the second and/or third nauplius and prolonged development of the final copepodite stage. Once adulthood is reached, males are usually short-lived, but females can live for weeks to months in the laboratory. Adult longevity in the sea is, however, on the order of only a few days. The evolution of developmental patterns is discussed in the context of physiological constraints, along with consideration of possible relationships between stage-specific mortality rates and life history strategies. Physiological constraints may operate at critical bottlenecks in development (e.g. at the first feeding nauplius, N6, and the fifth copepodite stage). High mortality of eggs may explain why broadcast eggs hatch 2–3 times faster than eggs carried by females in a sac; high mortality of adults may explain why adults do not grow rather they maximize their reproductive effort by partitioning all energy for growth into egg production.     

白斑狗鱼胚胎和仔鱼发育的研究

白斑狗鱼 (EscoxluciusLinnaeus) ,卵圆球形 ,呈金黄色 ,直径为 1.9— 2 .2mm ,具黏性。在 5— 11℃的温度下 ,受精卵历时 185h 18min发育后孵出 ,所需总积温为 2 6 4 1 37℃ ,胚胎发育可划分为 6个阶段 ,33个发育时期。初孵仔鱼全长 7 0— 7 7mm ,从孵出到各鳍形成需 2 1d。胚胎发育各期及仔鱼的主要形态特征均被描述     

Variation, plasticity and modularity in anuran development

Although anuran development is generally thought to be relatively conservative, a great deal of variation is evident when different species are compared. This report summarizes the results of comparative analyses of different aspects of anuran development. These include differences in sequence and timing of developmental events, the effects of genome size, and the effects of different life history strategies on anuran embryogenesis. The results show that anuran development is plastic at the evolutionary level, and many changes can occur in the developmental processes of anurans throughout their evolution. Changes are apparently rapid, and are as common as cladogenic events. This evolutionary plasticity can be attributed to the modular nature of anuran development. Different modules can shift relative to one another in time or in space, creating variations in the observed developmental patterns. However, shifts in modules can occur even without having a significant effect on the ultimate outcome of the process. I discuss the implications of the modular nature of development on the evolution of anuran development, and of the group in general.     

成纤维细胞生长因子18(FGF18)的研究进展

成纤维细胞生长因子18 (fibroblast growth factor 18,FGF18)是成纤维细胞生长因子家族( FGFs)的成员之一.研究发现,FGF 18不仅在骨骼发育和生长期对软骨形成和成骨生成起着重要的作用,其功能也已延伸至其他许多生物过程,尽管对FGF18作为一个有用治疗靶点发挥作用的功能和机制仍有待进一步的发现及研究.现针对FGF18的特点,及其在骨骼发育中的功能,特别其在未来具有潜在应用领域上的研究进展进行综述.     

Zinc deficiency and growth

Zinc deficiency remains a serious health problem worldwide affecting developed as well as developing countries. Despite the evidence proving that zinc deprivation during the periods of rapid growth negatively affects the cognitive brain as well as sexual development, there are few complete studies carried out in children. The present article proposes a revision of the evidence gathered until now on the relationship existing between zinc deficiency and intellectual and sexual development during the stages of childhood, preadolescence, and adolescence. An erratum to this article is available at .     

单叶蔓荆(唇形科)的横生胚珠和葱型胚囊

利用常规石蜡制片技术研究了单叶蔓荆胚珠和胚囊的发育以丰富牡荆亚科的胚胎学资料。单叶蔓荆的胚珠横生、单珠被、薄珠心、具珠被绒毡层、珠孔狭长。胚囊发育类型为葱型,可能由蓼型胚囊演变而来。葱型胚囊在牡荆亚科及整个唇形科属首次报道。     

Exogenous fibronectin is not required for organogenesis in vitro

Summary The biological effect of plasma fibronectin on the differentiation of embryonic mouse kidney and tooth was studied in organ cultures. Transferrin (50μg/ml) was a strong mitogen for kidney cells, whereas, the addition of soluble fibronectin (50 to 250 μg/ml) had no detectable effect on differentiation or proliferation. The same serum-free, transferrin-containing medium did not support tooth differentiation. however, fibronectin was not a necessary serum component because fibronectin-free serum supported tooth development. It was demonstrated with antibodies specific for human fibronectin that the exogenously added human fibronectin at 50 μg/ml did not become incorporated to the cultured organs. Only minimal incorporation to the kidney basement membrane area was observed when fibronectin concentration was 250μg/ml. The mesenchymal stroma and the basement membranes of the kidney and tooth rudiments cultured in fibronectin-free media stained intensely with conventional fibronectin antibodies, indicating endogenous production of fibronectin. Outgrowing epithelial cells from isolated kidney tubules produced fibronectin as well as laminin. The results suggest that the fibronectin found in the stroma and basement membranes is an endogenous product of the developing tissues and that plasma fibronectin is not required for in vitro organogenesis. The results also indicate that it is difficult to study the effect of fibronectin on morphogenetic processes because it may not penetrate the organ explants in vitro. This work was supported by grants from the Sigrid Jusélius Foundation, Finska L?kares?llskapet, Finnish Life Insurance Companies and Grant CA 28896 and Cancer Center Support Grant CA 30199 from the National Cancer Institute, Department of Health and Human Services, Washington, D.C.     

Ecdysteroid titres during ovarian and embryonic development inBlaberus craniifer

Summary InBlaberus craniifer, the maturation of the oocytes is accompanied by morphological modifications of the surrounding follicular cells and by variations in the ecdysteroid titre.Before the follicular cells form the chorion, they synthesise ecdysteroids which pass into the terminal oocytes to be stored. During the secretion of the chorion, before the release of the oocytes, one observes a decrease of the ecdysteroid titre in the ovaries. The hormonal titres in ovaries and haemolymph fluctuate in parallel, probably because ovaries leak into the haemolymph.The terminal oocyte of each ovariole is deposited into the incubating pouch where the entire embryonic development takes place. There is first a decrease of the ecdysteroids synthesised by the follicular cells and stored in the eggs. One then observes 3 ecdysteroid peaks during each of the 2 cycles of the development. During the first cycle, the first peak coincides with the end of the metamerisation, the second peak with the secretion of the first cuticle and the third with the transition between the first and the second cycle. For the second cycle, the first peak coincides with the loss of the capacity to regenerate, the second with the secretion of the second cuticle and the third with the hatching period.The third peak of each of these 2 cycles is atypical compared with what is known of the larval cycles. The analysis of the hatching peak has shown that it is principally composed of a compound more polar than -ecdysone     

Targeted Overexpression of Drosophila Transglutaminase-B Induced Characteristic Phenotypes in a Manner Similar to Transglutaminase-A

The Drosophila transglutaminase gene (CG7356) encodes two transglutaminases, dTG-A and dTG-B. To understand the roles of dTG-B during the development of the fly, we examined phenotypes induced through ectopic expression of dTG-B. Overexpression of dTG-B induced rough eye and extra wing crossvein phenotypes. These phenotypes were similar to those observed in the case of targeted overexpression of dTG-A.     

白点鲑胚胎与仔鱼发育

通过Bouin's液、5%的福尔马林、透明液固定和活体解剖观察等4种不同方法,对白点鲑(Salvelinus leucomaenis)胚胎和仔鱼发育进行了系统观察,描述了早期发育过程。白点鲑受精卵为端黄卵,沉性,橙黄色,呈圆球形。在水温3.40～8.89℃,受精卵历时1 944 h,经历6个阶段的胚胎发育破膜孵出仔鱼;初孵仔鱼全长(17.89±0.32)mm,破膜后73 d各鳍条发育完全,并出现"幼鲑斑",破膜后350d鱼体外部形态与成鱼基本相同。将白点鲑与几种鱼类进行了对比,并且探讨了其胚胎发育特点。经比较4种不同观察方法,Bouin's液固定后剥离卵膜观察是研究白点鲑等卵膜较厚鱼类的理想方法。