The relations between neurite development and the subcellular structures of hippocampal neuron somata

The relations between neurite development and the subcellular structures of the hippocampal neuron somata have been studied with atomic force microscopy (AFM). The conformation of the neuron was achieved by the synapse-like structures found by AFM scanning along a neurite of the cell. Hippocampal neuron somata were divided into two or three subcellular parts by one or two horizontal grooves. The upper parts increased while the middle and the lower parts decreased with the number and the length of the neurites and the formation of the neurosynapse-like structures. When neurites sufficiently developed, the middle parts were lost and the lower parts became very small. Mitosis inhibitors could prevent the formation of such subcellular structures of hippocampal neuron somata, which was accompanied by the loss of ability to form synapse-like structures. These results suggest that the upper parts are responsible for neuritogenesis while the middle and the lower parts only have indirect effect on it.     

Ciliated band structure in planktotrophic and lecithotrophic larvae of Heliocidaris species (Echinodermata: Echinoidea): a demonstration of conservation and change

The evolution of lecithotrophic (non-feeding) development in sea urchins is associated with reduction or loss of structures found in the planktotrophic (feeding) echinopluteus larvae. Reductions or losses of larval feeding structures include pluteal arms, their supporting skeleton and the ciliated band that borders them. The barrel-shaped lecithotrophic larva of Heliocidaris erythrogramma has, at its posterior end, two or three ciliated band segments comprised of densely packed, elongate cilia. These cilia may be expressions of the epaulettes that would have been present in an ancestral larval form, represented today by the feeding echinopluteus of H. tuberculata . We compared the development and cellular organization of the larval ciliary structures of both Heliocidaris species to assess whether the ciliary bands of H. erythrogramma are expressions of the feeding ciliated band or epaulettes of an echinopluteus. Epaulette development in feeding larvae of H. tuberculata involves separation of specific parts of the ciliated band from the rest of the feeding ciliated band, hyperplastic addition of ciliated cells and hypertrophic growth of the cilia. Like epaulettes, the ciliated bands of H. erythrogramma are composed of long spindle-shaped cells arranged in a cup-shaped collection that bulges into the blastocoel; and these cells have elongated cilia. In their developmental origin and topological arrangement however, the ciliated bands of H. erythrogramma correspond more closely with parts of the pluteal feeding ciliated band than with epaulettes. The larvae of this echinoid appear to develop epaulette-like bands from parts of the original (but reduced) feeding ciliated band. The evolution of development in H. erythrogramma has thus involved both conservation and change in echinopluteal ciliary structures.     

The effect of domestication on brain size and composition in the mink (Mustela vison)

The sizes of total brain, the five fundamental brain parts, and certain telencephalic structures were measured in wild mink ( Mustela vison energumenos ) and ranch mink of a Dark Standard strain of the same species. By means of intraspecific allometric methods for analysing the relationship between brain weight and body weight (net carcass weight), the volumes of the brain parts were compared in both groups. In general, total brain, as well as all the parts measured, were smaller in size in ranch mink independent of body size, age, and sex, indicating that domestication has led to a decrease in size. There were differences in the amount of decrease in various brain parts. These are discussed in connection with domestication time, with comparable results obtained in other species, and with regard to the functional importance of the brain parts.     

Testing the effect of treatment in experiments with correlated binary outcomes.

This paper considers the problem of testing for treatment effect in a randomized experiment with correlated binary outcomes, representing success or failure for different "parts" of a randomized unit. Attention is restricted to tests that are based on a summary score for each individual randomized, and thus are valid regardless of the precise nature of the correlation among parts. The focus is on the efficiency of such tests under various correlation structures, with special emphasis on the case in which the correlation among parts within an individual differs across treatment groups. A class of summary score statistics is defined, and optimal testing is discussed for some simple situations. Three potential general-purpose tests also are described: (1) the ratio estimate test discussed by Henderson et al. (1988, Controlled Clinical Trials 9, 189-205); (2) a modified ratio estimate test with adjusted weighting based on the within-individual correlation between parts; (3) a test defined by applying the Mantel-Haenszel procedure to the proportion of individuals with at least one failure, stratifying by the number of parts. For these general-purpose tests, numerical calculations of asymptotic efficiency are presented under a wide range of designs and correlation structures. On the basis of these results, some practical recommendations for choosing a test are made.     

Phenols in reproductive and somatic structures of lichens: a case of optimal defence?

Optimal defence theory (ODT) attempts to explain variation in plant secondary compounds between different species, different growth conditions and different parts of individual plants. The theory is widely applied to vascular plants and more recently also to seaweeds. Surprisingly, ODT has gained little attention as potential explanation on the distribution of lichen secondary metabolites. In the present study, we analysed intrathalline variation in total phenol content and phenol spectra between reproductive and somatic structures of three foliose lichens, Xanthoria parietina , Vulpicida pinastri and Hypogymnia physodes . The results showed that the concentration of phenolic compounds is higher in sorediate than in non-sorediate lobe ends of V. pinastri and H. physodes as well as in apothecia of X. parietina compared to other parts of the thallus. These results were in accordance with ODT predicting higher allocation of phenols in structures that are most important for the fitness of an individual genet or ramet. This pattern was parallel in all species regardless whether the compounds originate from either acetate-mevalonate or shikimic acid pathways. Moreover, both sexual ( X. parietina apothecia) and asexual (soralia of V. pinastri and H. physodes ) reproductive structures were higher in phenols compared to somatic tissue.     

A molecular dynamics approach for the generation of complete protein structures from limited coordinate data

Generation of full protein coordinates from limited information, e.g., the Cα coordinates, is an important step in protein homology modeling and structure determination, and molecular dynamics (MD) simulations may prove to be important in this task. We describe a new method, in which the protein backbone is built quickly in a rather crude way and then refined by minimization techniques. Subsequently, the side chains are positioned using extensive MD calculations. The method is tested on two proteins, and results compared to proteins constructed using two other MD-based methods. In the first method, we supplemented an existing backbone building method with a new procedure to add side chains. The second one largely consists of available methodology. The constructed proteins are compared to the corresponding X-ray structures, which became available during this study, and they are in good agreement (backbone RMS values of 0.5–0.7 Å, and all-atom RMS values of 1.5–1.9 Å). This comparative study indicates that extensive MD simulations are able, to some extent, to generate details of the native protein structure, and may contribute to the development of a standardized methodology to predict reliably (parts of) protein structures when only partial coordinate data are available. © 1994 John Wiley & Sons, Inc.     

Structure of the uncomplexed DNA repair enzyme endonuclease VIII indicates significant interdomain flexibility

Escherichia coli endonuclease VIII (Nei) excises oxidized pyrimidines from DNA. It shares significant sequence homology and similar mechanism with Fpg, a bacterial 8-oxoguanine glycosylase. The structure of a covalent Nei-DNA complex has been recently determined, revealing critical amino acid residues which are important for DNA binding and catalysis. Several Fpg structures have also been reported; however, analysis of structural dynamics of Fpg/Nei family proteins has been hindered by the lack of structures of uncomplexed and DNA-bound enzymes from the same source. We report a 2.8 A resolution structure of free wild-type Nei and two structures of its inactive mutants, Nei-E2A (2.3 A) and Nei-R252A (2.05 A). All three structures are virtually identical, demonstrating that the mutations did not affect the overall conformation of the protein in its free state. The structures show a significant conformational change compared with the Nei structure in its complex with DNA, reflecting a approximately 50 degrees rotation of the two main domains of the enzyme. Such interdomain flexibility has not been reported previously for any DNA glycosylase and may present the first evidence for a global DNA-induced conformational change in this class of enzymes. Several local but functionally relevant structural changes are also evident in other parts of the enzyme.     

Comparative study of bovine ocular lens proteins in native tissue and an extract using the x-ray diffraction method

It has been shown that the maxima (Bragg-spacings 4,5-19 A) on the X-ray diffraction patterns of the bovine lens native tissues from nuclear and cortical parts are predominantly due to the water-soluble crystallin intramolecular structure. The structures of water-soluble and water-insoluble fractions from bovine lens nucleus and cortex were qualitatively compared. Reversible dependence of the lens water-soluble protein structure on water content in the system was demonstrated.     

Transdetermination in the homeotic eye--antenna imaginal disc of Drosophila melanogaster

The effects of homeotic mutations on transdetermination in eye-antenna imaginal discs of Drosophila melanogaster were studied. After 12 days of culture in vivo, antenna discs transformed to ventral mesothorax by AntpNs or AntpZ, transdetermined to notum and wing structures four to five times more frequently than the corresponding wild-type antenna discs. Likewise, eye discs transformed to dorsal mesothorax by eyopt transdetermined to leg structures, also extremely frequently (90%). It seems that, during culture, homeotic antenna as well as homeotic eye discs tend to complete the structural inventory of the mesothoracic segment. Transdetermination in the homeotic disc parts is interpreted as a regeneration process which reestablishes an entire segment, i.e., the ventral mesothoracic portion (leg) in the antenna disc regenerates dorsal mesothoracic parts, and the dorsal mesothoracic portion in the eye disc (wing) regenerates ventral mesothoracic parts, respectively. This implies that antenna and leg discs (ventral qualities) as well as eye and wing discs (dorsal qualities) are serially homologous. The transdetermination frequency of the untransformed eye disc to notum and wing structures is enhanced by Antp to the same extent as is the transdetermination frequency of the antenna disc. The first allotypic wing disc structure formed by the eye disc is notum, followed by structures of the anterior wing compartment and finally by posterior wing structures. No evidence for such a sequence was found in the transdetermination pattern of the antenna disc.     

Morphology and development of secretory structures in Hypericum perforatum and H. richeri

Secretory organs are a specialised anatomical feature of plants, these tissues function in the production and/or storage of specific chemical substances, which often have pharmacological properties. The genus Hypericum is characterised by the presence of specialised secretory structures such as black nodules, translucent glands and secretory canals. The presence of these structures is not homogeneous for all the species or between the various floral and vegetative parts of the plants. In this study, we have compared the distributions, morphology and development of secretory structures in the leaves of H. perforatum and H. richeri. Whilst, black nodules occurred in both species, translucent glands followed different development stages depending on the leaf age.     

Three-dimensional structure of the ciliate Didinium nasutum nucleoli

The nucleolar organization in ciliate Didinium nasutum somatic interphase nuclei was studied using serial ultrathin sections and compared for various physiological states of the cell, namely, fed ciliates, starved ciliates, and dormant cysts. It has been shown that the interphase nucleoli are large structures with a complex architecture: the fibrillar component forms an intricate network in the macronucleus space, while the granular component is located inside this network. The structures looking as individual nucleoli in single sections are actually parts of branched nucleolar networks. The intricate nucleolar networks do not disintegrate after a 30-h starvation; however, the granular component becomes denser and develops numerous cavities filled with fine fibrils of a nonribonucleoprotein nature. In fed D. nasutum, the fibrillar structures on the periphery of nucleoli contain numerous pores (virtually absent in starved cell nucleoli), which can potentially serve for transporting newly synthesized rRNP. Branched nucleolar networks are undetectable in cysts. Their nucleoli are individual structures consisting mainly of the fibrogranular component.     

Short-term progressive early diagenesis in density bands of recent corals:Porites Colonies,Mauritius Island,Indian Ocean

Summary The growth history of some recentPorites colonies of Mauritius Island (Indian Ocean) was dated by sclerochronological methods. Couples of high-density and low-density bands represent the annual growth rate of the corals and allow the growth pattern of every year in the corallum to be counted. The growth and structure of the skeletons ofPorites solida andPorites lutea were investigated. Older parts of the aragonitic skeleton in these 10 to 20 year old corals show various secondary microstructures resulting from alterations and thickenings of the elements of the skeleton. The primary needle-like aragonite crystals are absent in older parts of the corallum and blocky aragonitic cements can occur. Pores and primary skeletal elements are overgrown by new microstructures. These microstructures are caused by secondary cementation and exhibit frontal zones (Stirnzonen), zigzag-like and pseudolamellar-structures. The lamellar structures can be compared with similar structures in the exoskeleton of some Rugosa. A very short early diagenesis within the recent corals is responsible for the thickening and alteration of skeletal elements. It occurs only 4 to 5 years after the formation of the skeleton and tends to increase in importance in older parts of the corallum. Nevertheless, there is no proof for any alteration of aragonite to calcite.     

Analysis of the steric strain in the polypeptide backbone of protein molecules.

The extent to which local strain is present in the polypeptide backbone of folded protein molecules has been examined. The occurrence of steric strain associated with nonproline cis peptide bonds and energetically unfavorable main chain dihedral angles can be identified reliably from the well ordered parts of high resolution, refined crystal structures. The analysis reveals that there are relatively few sterically strained features. Those that do occur are located overwhelmingly in regions concerned with function. We attribute this to the greater precision necessary for ligand binding and catalysis, compared with the requirements of satisfactory folding.     

Survival of Helicoverpa armigera larvae on and Bt toxin expression in various parts of transgenic Bt cotton (Bollgard II) plants

There is no conclusive evidence that Helicoverpa spp. (Lepidoptera: Noctuidae) in Australia have evolved significant levels of resistance to Bollgard II^® cotton (which expresses two Bt toxin genes, cry1Ac and cry2Ab). However, there is evidence of surviving larvae on Bollgard II cotton in the field. The distribution and survival of early‐instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae were examined on whole Bollgard II and non‐Bt cotton plants in greenhouse bioassays. The expression of Cry toxins in various parts of Bollgard II plants was compared to the survival of larvae in those locations. Only 1% of larvae survived after 6 days on greenhouse‐grown Bollgard II plants compared to 31% on non‐Bt cotton plants. Overall, and across all time intervals, more larvae survived on reproductive parts (squares, flowers, and bolls) than on vegetative parts (leaves, stems, and petioles) on Bollgard II plants. The concentration of Cry1Ac toxin did not differ between plant structures, whereas Cry2Ab toxin differed significantly, but there was no relationship between the level of expression and the location of larvae. This study provides no evidence that lower expression of Cry toxins in the reproductive parts of plants explains the survival of H. armigera larvae on Bollgard II cotton.     

Allometric growth and adaptive value of exaggerated body parts in the larvae of Gratiana spadicea (Klug) (Coleoptera: Chrysomelidae)

1. Larvae of tortoise beetles present exaggerated body parts in association with an abdominal shield, which is made of faeces and exuviae that are deposited on the urogomphi throughout ontogeny. Growth trajectories and scaling relationships of these functional structures associated with the shield, if any, are unknown. 2. This study of Gratiana spadicea first tested, under field conditions, whether there is adaptive value associated with the shield regarding protection against predation and sunlight. Then, under laboratory conditions, the growth trajectory and allometric relationships among body parts were investigated, including scoli, individual and apparent furcae, and shield. The influence of food deprivation on the development of these structures was also determined. 3. Findings from previous studies were confirmed, suggesting that the adaptive value assigned to the shield is related to protection against predators. The present study demonstrated for the first time that the shield acts as a parasol in cassidines, decreasing the exposure of their larval body to sunlight. The scoli and apparent furca are exaggerated structures of G. spadicea, the development of which involves allometric growth and greater energetic investment (positive allometry) during ontogeny. There was proportionally less energetic investment for somatic construction of individual furca (negative allometry) due to the accumulation of the exuviae. 4. The possible consequences, in terms of developmental costs and survivorship benefits associated with the evolution of such exaggerated structures, are discussed.     

植物光合结构与非光合结构的功能平衡：来自三种亚热带乔木树种的实验证据

植物的地上部分和地下部分存在功能性平衡现已十分清楚,但植物的地上部分是否在其光合结构（叶组织）和非光合结构（枝和茎）之间也存在功能性平衡尚不明晰,本文提出两个研究假设并检验之：1）植物地上部分在其光合与非光合结构之间存在功能性平衡;2）此功能性平衡的维持依赖于对光合和非光合结构生物量分配的调节,为验证此假设,采用枝叶修剪的方式（连续两年修剪,四个修剪强度：0,20%,50%,70%）对3种亚热带乔木树种榕（Ficus microcarpa),黄桷树（Ficus virens)和樟（Cinnamomum camphora)进行了研究。结果表明,修剪使所有树种地上部分的光合与非光合结构生物量比率（P/NP）立即下降,下降程度随修剪强度的程式高而增大,但不论是首次修剪还是第二次修剪,修剪处理一年后,修剪株地上部分的光合与非光合结构生物量比率升高,且此生物量比率不低于非修剪株的光合与非光合结构生物量比率。此研究结果证实了植物地上部分光合与非光合结构间存在功能性平衡的假设,与假设一致。植株的生物量分配在修剪后发生了改变;修剪株加大了对光合结构（叶组织）的生物量分配（大量的新生产地上部分生物量被分配到光合结构）,同时却减少了对非光合结构（枝和茎）的分配,此分析格局的改变保证了光合与非光合结构功能性平衡的恢复与维持,可以认为,通过改变生物量分配格局以维持光合与非光合结构功能平衡是植物低御外来干扰和/或损伤的一种有效策略。     

Terpenoids from Anthemis austriaca Jacq

The aerial parts of Anthemis austriaca Jacq. afforded five new sesquiterpene lactones (two of which are dimeric guaianolides) and three new guaiane type sesquiterpene acids In addition, seven known terpenoids were also found in the studied species. Their structures were elucidated by spectral methods.     

Morphogenesis in the Heterotrich Ciliate Climacostomum virens. I. Oral Development During Cell Division

The principal characteristics of stomatogenesis during division in Climacostomum virens are: (A) Kinetosomal proliferation on the left side of a variable number of kineties in the ventral somatic cortex forms an oral primordium consisting of several kinetosomal fields, which then fuse to form a single anarchic field. (B) A constant topographical relationship exists between the primordium and a well defined cortical pattern, the zone of discontinuity. (C) The anarchic field primordium divides into 2 unequal parts—to the left, the AZM primordium, and to the right, the paroral primordium, which differentiates into the apical membranelles, the peristomial field, and the buccal tube. (D) Preoral and oblique kineties of the somatic cortex form along the right side of the paroral primordium. (E) Parental oral structures are partially dedifferentiated. Stomatogenesis in C. virens and other heterotrichs is compared.     

Mosaic pattern of genital divergence in three populations of Schistocerca lineata Scudder, 1899 (Orthoptera: Acrididae: Cyrtacanthacridinae)

Sexual selection theory predicts that genital structures in isolated populations are likely to diverge, but male genitalia are often species-specific, which led to the idea that male genitalia are relatively invariable within species. Previous allometric studies collectively suggested that male genitalia are intraspecifically invariable in size compared with external body parts. We investigated whether male genitalia are invariable in shape in three populations of a grasshopper Schistocerca lineata Scudder, 1899, using two independent methods of geometric morphometric analyses. Specifically, we focused on the idea that male genitalia are complex structures consisting of many functionally different components, and studied how these individual parts diverge among three populations. Individual components of male genitalia show different population-level divergence, resulting in the mosaic pattern of genital divergence. Individual components diverge independently from each other. Body size is positively correlated with genitalia size, but is significantly correlated with the shape of only one of the three genital structures we measured. Thus, different components of male genitalia may be influenced by different evolutionary processes. This study is the first to show that components of complex genitalia evolve separately within a species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 289–301.