Observations on an Intranuclear Microsporidian in Lymphoblasts from Farmed Atlantic Halibut Larvae (Hippoglossus hippoglossus L.)

ABSTRACT. An intranuclear microsporidian was observed in lymphoblasts from the kidney of farmed Atlantic halibut larvae ( Hippoglossus hippoglossus ). In addition to spores, intranuclear pre-spore stages were observed. Uninucleated stages with a slight thickening of the cell membrane were the most simple developmental stages observed. Multinucleated developmental stages contain electron-lucent vesicles and electron-dense discs. The spores are ovoid and measure 2.9 × 1.2 μm (mean). Sporophorous vesicles, diplokarya and mitochondria were not observed in any of the developmental stages. The developmental stages observed are similar to those of the family Enterocytozoonidae, genus Enterocytozoon. However, there are several differences between the present species and E. bieneusi from enterocytes in man. The relationship to the other species in the genus, E. salmonis can only be determined when all the developmental stages of the species from Atlantic halibut are identified.     

Lateral line placodes are induced during neurulation in the axolotl

In order to determine the time window for induction of lateral line placodes in the axolotl, we performed two series of heterotopic and isochronic transplantations from pigmented to albino embryos at different stages of embryogenesis and assessed the distribution of pigmented neuromasts in the hosts at later stages. First, ectoderm from the prospective placodal region was transplanted to the belly between early neurula and mid tailbud stages (stages 13-27). Whereas grafts from early neurulae typically differentiated only into epidermis, grafts from late neural fold stages on reliably resulted in differentiation of ectopic pigmented neuromasts. Second, belly ectoderm was transplanted to the prospective placodal region between early neurula and tailbud stages (stages 13-35). Normal lateral lines containing pigmented neuromasts formed in most embryos when grafts were performed prior to early tailbud stages (stage 24) but not when they were performed later. Our findings indicate that lateral line placodes, from which neuromasts originate, are already determined at late neural fold stages (first series of grafts) but are inducible until early tailbud stages (second series of grafts). A further series of heterochronic transplantations demonstrated that the decline of inducibility at mid tailbud stages is mainly due to the loss of ectodermal competence.     

Analysing growth and development of plants jointly using developmental growth stages

Background and Aims Plant growth, the increase of organ dimensions over time, and development, the change in plant structure, are often studied as two separate processes. However, there is structural and functional evidence that these two processes are strongly related. The aim of this study was to investigate the co-ordination between growth and development using mango trees, which have well-defined developmental stages.Methods Developmental stages, determined in an expert way, and organ sizes, determined from objective measurements, were collected during the vegetative growth and flowering phases of two cultivars of mango, Mangifera indica. For a given cultivar and growth unit type (either vegetative or flowering), a multistage model based on absolute growth rate sequences deduced from the measurements was first built, and then growth stages deduced from the model were compared with developmental stages.Key Results Strong matches were obtained between growth stages and developmental stages, leading to a consistent definition of integrative developmental growth stages. The growth stages highlighted growth asynchronisms between two topologically connected organs, namely the vegetative axis and its leaves.Conclusions Integrative developmental growth stages emphasize that developmental stages are closely related to organ growth rates. The results are discussed in terms of the possible physiological processes underlying these stages, including plant hydraulics, biomechanics and carbohydrate partitioning.     

Vertebral Abnormalities Following Heat Shock in Xenopus Embryos

Xenopus embryos were heat-shocked at several stages of development and vertebral abnormalities were examined by means of in situ staining. A high incidence of vertebral abnormalities was evident in larvae treated at the neurula stages (stages 15 and 20) and at the tailbud stages (stages 32 and 35). Heat shock at the neurula stages led to malformed vertebrae and their fusion following an altered arrangement of the arcualia. Heat shock at the tailbud stages induced an asymmetric arrangement of the sacrum and a change in the number of vertebrae, but the arrangement of the arcualia was not affected. Early events of the development of the vertebral column are discussed in relation to somitogenesis.     

Crucial stages of embryogenesis of R. arvalis: Part 1. Linear measurements of embryonic structures

Investigations of individual variability have allowed us to reveal the crucial (= nodal) stages in embryogenesis of the moor frog (Rana arvalis Nills.). These crucial stages are: the late gastrula stage (stages 18-20), the hatching stages (stages 32-33) and, apparently, early metamorphosis (stage 39). Moreover, we have found that each embryonic structure passes through its specific crucial stages. For example, stage 34 is crucial for the trait "tail width" but is internodal for all other embryonic traits. At this stage, larva passes from an attached to a free-swimming life style. We also found considerable differences between the different frog populations in the the level of developmental variability. These differences were associated with internodal developmental stages.     

草鱼同工酶发育遗传学研究——Ⅱ.早期发育过程中的同工酶分析

采用淀粉凝胶电泳技术研究了草鱼早期发育过程中(受精后0—200小时)6种同工酶系统(LDH、MDH、GDH、ADH、IDH、EST)的表达谱式。除了ADH以外,其余5种同工酶系统均具有明显的发育变化谱式。根据早期发育过程中同工酶的变化谱式及其组织分布,草鱼的同工酶可分为三大类型:(1)在未受精卵及早期发育过程中一直存在,并常有较广泛的组织分布;(2)未受精卵及早期发育过程中均不存在,一般仅分布于少数几种组织中;(3)未受精卵及胚胎发育早期不存在,直到早期发育过程中某一特定时期才开始出现。     

Integrating function across marine life cycles

Complex life cycles involve a set of discrete stages that candiffer dramatically in form and function. Transitions betweendifferent stages vary in nature and magnitude; likewise, thedegree of autonomy among stages enabled by these transitionscan vary as well. Because the selective value of traits is likelyto shift over ontogeny, the degree of autonomy among stagesis important for understanding how processes at one life-historystage alter the conditions for performance and selection atothers. We pose 3 questions that help to define a research focuson processes that integrate function across life cycles. First,to what extent do particular transitions between life-historystages allow those stages to function as autonomous units? Weidentify the roles that stages play in the life history, typesof transitions between stages, and 3 forces (structural, genetic/epigenetic,and experiential) that can contribute to integration among stages.Second, what are the potential implications of integration acrosslife cycles for assumptions and predictions of life-historytheory? We provide 3 examples where theory has traditionallyfocused on processes acting within stages in isolation fromothers. Third, what are the long-term consequences of carryoverof experience from one life cycle stage to the next? We distinguish3 scenarios: persistence (effects of prior experience persistthrough subsequent stages), amplification (effects persist andare magnified at subsequent stages), and compensation (effectsare compensated for and diminish at subsequent stages). We usethese scenarios to differentiate between effects of a carryoverof state and carryover into subsequent processes. The symposiumintroduced by our discussion is meant to highlight how discretestages can be functionally coupled, such that life cycle evolutionbecomes a more highly integrated response to selection thancan be deduced from the study of individual stages.     

Postembryonic development of Tisbe gracilis (T. Scott) (Copepoda, Harpacticoida)

All six naupliar and five copepodite stages of Tisbe gracilis (T. Scott, 1895) are described. A key for the identification of the nauplius stages is given. The oral appendages of all copepodite stages are described. Sexual dimorphism is visible from the copepodite IV stage on.     

A review of the prognostic role of cytogenetic, phenotypic, morphologic, and immune function characteristics in chronic lymphocytic leukemia

Recent reports of successfully completed cytogenetic studies using polyclonal B-cell activators demonstrate that trisomy-12 and 14 q+ are the most frequently observed chromosomal abnormalities in B-cell chronic lymphocytic leukemia (CLL). It appears that when trisomy-12 is accompanied by yet another abnormality, the prognosis of patients is uniformly poor. Patients in early stages of CLL retain delayed hypersensitivity reactivity, while those in advanced stages are usually anergic. The lymphocytes from venous blood of patients with CLL appear to retain at least some ability to respond to stimulation with mitogens in early stages, whereas in advanced stages they show no response to mitogens. Serum immunoglobulin levels are normal in the early (0 and I) stages, are markedly decreased in the advanced (III and IV) stages, and are somewhat between these extremes in the intermediate (II) stage of CLL. Prolymphocytic leukemia and prolymphocytoid transformation of CLL are indicators of poor prognosis, while a morphological variant characterized by large granular lymphocyte is associated with good prognosis. At this time it is not possible to ascribe strong prognostic significance to phenotypic features of lymphocytes in B-CLL; however, studies currently in progress may soon provide important insights on this subject. We have reviewed the pertinent literature and we also present a summary of results from our laboratory.     

Recruitment and mortality of early post-settlement stages of benthic algae

Four transitional life history stages are generally recognized for benthic marine algae. On the basis of differences in size, we propose two more: young germlings and young juveniles. Three of these (spores or zygotes, young germlings, and germlings) are considered early post-settlement (EPS) stages. Many of the available data on recruitment and mortality were not collected with EPS stages specifically in mind, and considerable extrapolation and inference are required to interpret effects on early phases. Data on EPS stages, and grazing in particular, are based on the disappearance of early stages (laboratory or field experiments, including outplantings), on indirect information on mortality from manipulations of grazers or juvenile stages, and combinations of observation and manipulation. We also provide original data on the effects of water motion and canopy sweeping on zygote mortality.

The most notable finding is the variability in, and multiplicity of, factors preventing successful recruitment of early life stages. Six intrinsic and about 17 extrinsic factors and/or processes were reported to affect recruitment and mortality. Grazing, canopy, and turf effects appear to be most important, but less well studied factors such as desiccation and water motion may be as important for early stages. Our review indicates that recruitment is highly variable, even episodic, and that mortality at this period is high. Combined, these elements suggest that chance events during EPS stages may play a large role in survival, and perhaps the evolution of benthic algae.     

Specific cellular expression of monoamine oxidase B during early stages of quail embryogenesis

Monoamine oxidase-B (MAO-B) is one of two distinct molecular forms of MAO that in part regulate the cellular levels of biogenic amines. In order to determine whether discrete cell populations known to express aminergic properties in the vertebrate embryo also express MAO-B, the distribution of MAO-B-immunoreactive cells was examined in early developing quail embryos. Two major patterns of staining emerge. First, tissues known to express several aminergic characteristics are initially MAO-B positive at early stages of development and continue to express immunoreactivity through Zacchei stage 20, the oldest stage examined. These include cells of the sympathetic and some cranial and trunk sensory ganglia (beginning at stage 13), the pancreas (stage 14), and the brain stem raphe (stage 14). Second, other structures that contain or accumulate biogenic amines are transiently MAO-B immunopositive during early stages of development. These tissues include extraembryonic yolk sac and presumptive gut endoderm (with most intense staining between stages 8 and 13), the ventral trunk neural tube (stages 14 and 16), and the notochord (stages 8–10). MAO-B immunoreactivity disappears from these regions at different stages, and none are MAO-B positive by stage 19–20. Other structures without known aminergic properties during early development also stain; these include liver (stage 20), mesenchymal cells that surround the Wolffian duct and lung buds (stages 14 and 18), and endothelial cells surrounding the dorsal aorta (stages 14 and 20). In general, however, MAO-B appears to be distributed in embryonic tissues that can use this enzyme to regulate biogenic amine levels either transiently or during initial phenotypic expression of aminergic traits.     

Crucial stages of embryogenesis of <Emphasis Type="Italic">R. arvalis</Emphasis>: Part 1. Linear measurements of embryonic structures

Investigations of individual variability have allowed us to reveal the crucial (=nodal) stages in embryogenesis of the moor frog (Rana arvalis Nills.). These crucial stages are: the late gastrula stage (stages 18–20), the hatching stages (stages 32–33) and, apparently, early metamorphosis (stage 39). Moreover, we have found that each embryonic structure passes through its specific crucial stages. For example, stage 34 is crucial for the trait “tail width” but is internodal for all other embryonic traits. At this stage, larva passes from an attached to a free-swimming life style. We also found considerable differences between the different frog populations in the the level of developmental variability. These differences were associated with internodal developmental stages.     

The Life Cycle of Cryptochlora perforans (Chlorarachniophyta)

Observations on the behaviour of different life cycle stages, gamete fusions, and measurements of nuclear DNA contents in Cryptochlora perforans resulted in a first concept concerning life histories in Chlorarachniophyta: the life cycle of Cr. perforans is diplohaplontic (gamete fusion with karyogamy - mitosis - meiosis - mitosis). In the haploid as well as in the diploid life cycle phases amoeboid and coccoid stages occur. The isomorphic gametes are modified amoebae frequently without filopodia. Only haploid flagellate stages are known representing mito- or meiozoospores. Diploid coccoid stages have a granular cytoplasmic structure and may be somewhat larger than haploid ones. Nevertheless, positive identification of haploid (gametophytic) and diploid (sporophytic) stages is only possible on the basis of nuclear DNA contents.     

亚热带常绿阔叶林不同演替阶段土壤种子库的初步研究

 本文把四川缙云山亚热带常绿阔叶林的演替系列分成6个阶段：(1)弃耕地;(2)灌草丛;(3)马尾松林;(4)以马尾松为优势的常绿针、阔叶混交林;(5)以常绿阔叶树为优势的针、阔叶混交林;(6)常绿阔叶林。分别从每个阶段分3层采集0.5m2,l0cm厚度的5个小样地的土样,带回实验室,通过萌发法研究土壤种子库。得到如下结论：A、种子数量和物种多样性在演替早期阶段(从弃耕地到马尾松林)一般随演替发展而减少,种子数目随土层加深而降低;后期阶段(马尾松林到常绿阔叶林)种子数则大致随演替发展而增加;同一阶段各土层种子数差异不大。B、各演替阶段土壤种子库的种类组成均以草本植物为主。C、在湿度和光照比较一致的情况下,萌发种子数与温度成正相关。大多数种类的种子80%以上在实验的头六个星期内萌发。D、演替早期阶段的地上植物种类组成与土壤种子库中种类组成基本一致,演替后期阶段相关甚少。本文还讨论了土壤种子库研究的取样体积问题,以及土壤种子库在植被动态中的作用。     

Genetic damage by bifunctional agents in repair-active pre-meiotic stages of Drosophila males

Most of our understanding of germline mutagenesis in Drosophila is based on the DNA repair-inactive, haploid post-meiotic stages. The diploid, repair-active pre-meiotic stages are more relevant to the situation encountered in somatic cells. DNA mono-adducts induced by agents like methyl methanesulphonate (MMS) and ethylene oxide (EO) are well repaired in the pre-meiotic cell stages, and these agents show therefore, no or considerable lower mutagenic activity in these stages. In contrast, in this study the two bifunctional nitrogen mustards chlorambucil (CAB) and mechlorethamine (MEC) show significantly elevated mutant frequencies of both post- and pre-meiotic germ cells. Results were similar for the X-chromosomal and the autosomal (2nd) recessive lethal (RL) test. CAB and MEC were also active in stem cells, but in comparison with post-stem cell stages they seem to be better protected. The germ cell specific response in post- and pre-meiotic cell stages was for both nitrogen mustards comparable to mutagenic activity patterns observed in the specific locus test in the mouse.It was reported that for diepoxybutane (DEB), another cross-linking agent, the ratio of the RL frequency for the 2nd- and the X-chromosome was increased from 2.1 for post-meiotic stages to 9.5 for pre-meiotic stages. In own experiments aiming to confirm this observation, a high ratio was indeed found. The induction of large deletions by DEB could be the reason for this difference, since such lesions might include both a sex-linked lethal and a vital gene required for the development of spermatocytes into mature sperm. Similar differences were expected for CAB and MEC since they are also inducers of large deletions. But unexpectedly, no differences in 2nd/X RL ratio between post- and pre-meiotic cell stages were found for the nitrogen mustards. Possible causes such as distinct proportions of multi-locus deletions (MLDs), mitotic recombination and the formation of persistent lesions, are discussed.     

Phenological growth stages of olive trees (Olea europaea)

This paper describes the phenological growth stages of olive trees using the BBCH (Biologische Bundesanstalt, Bundessortenamt, Chemische Industrie) scale. Eight principal growth stages for bud, leaf and shoot development, inflorescence emergence, flowering, fruit development, fruit maturity and senescence and 32 secondary growth stages are described. Advantages of the BBCH scale over other methods are discussed.     

二倍体型与三倍体型卫氏并殖吸虫同工酶谱的发育变异及其分类学意义

采用生趣板状聚丙烯酰胺胶是民泳法分析比较了二倍体型与三倍体型卫氏并殖吸虫童虫、成虫的醛缩酶、已糖激酶和葡萄糖－６－磷酸脱氢酶的同工酶谱,结果显示２ｎ型与３ｎ型卫氏并殖吸虫在不同发育期之间及两型吸虫相应各发育期之间ＡＬＤ、ＨＫ及Ｇ６ＰＤ同工酶谱均显著变异,变异表现为两种方式,一种是在同一个基因座位区的同工酶的酶带数目