Lysosomes and yolk formation in the oocytes of Asterina gibbosa (Echinodermata,Asteroidea)

Summary

Primary lysosomes appear in the oocytes of A. gibbosa at the end of previtellogenesis. The lysosomes fuse with the cisternae of the endoplasmic reticulum and give rise to yolk globules containing acid phosphatase. The yolk globules then grow by fusion.     

Two new species of the liverwort genus Riccia L. from tropical Africa: R. somaliensis and R. erubescens

Abstract

Two new Riccia species, R. somaliensis and R. erubescens from Africa are described and illustrated. They are both classified in the subgenus Riccia, section Riccia. R. somaliensis has hyaline, somewhat frilly scales and apolar, wingless spores; R. erubescens has shiny dark, purple-red to bright cherry-red scales and polar, winged spores with numerous small areolae; its tissues are sometimes distorted by gelatinous globules that are gradually extruded on the dorsal surface.     

Development and roles of vitelline cells in eggshell formation in Fasciola gigantica

Summary

In Fasciola gigantica, vitelline cells are the major contributors to the formation of the eggshell. The vitelline cells develop in vitelline follicles that are located in the posterior third of the adult parasite's body, in the areas lateral to the uterus and the testis. Mature vitelline cells are released and transported to the Mehlis' gland-ootype complex via a series of vitelline ducts. Based on ultrastructural features, the developing vitelline cells are classified into four stages: stem cell, protein-synthetic, carbohydrate-synthetic and mature cell stages. At the protein-synthetic stage, the eggshell globules are formed, whereas during the carbohydrate-synthetic stage glycogen particles and glycan vesicles are synthesized. The mature vitelline cells are detached from the nurse cells, and pass successively into the intrafollicular, interfollicular, longitudinal and transverse vitelline ducts, to be stored in the vitelline reservoir before being transported to the ootype via the median vitelline duct. At the same time, ova are transported from the ovary through the oviduct into the ootype lumen where each becomes surrounded by a number of vitelline cells. Vitelline cells secrete eggshell globules to surround a group of vitelline cells and an ovum in the ootype lumen, and these globules coalesce into the definitive eggshell. In the middle part of the uterus fertilization occurs, after which the eggshell is completely formed. Within the egg proper, vitelline cells break down, releasing glycogen and other products to nourish the developing embryo.     

Gravity susception by buoyancy: floating lipid globules in sporangiophores of<Emphasis Type="Italic"> Phycomyces</Emphasis>

To elucidate the mechanisms of gravity susception that operate in the sporangiophore of Phycomyces blakesleeanus, we characterized the function and topography of a large apical complex of lipid globules. Stage-1 sporangiophores (without sporangium) possess a roughly spherical complex of 100–200 large lipid globules whose center is localized 110 m below the apex. The complex of lipid globules (CLG) is rather stable and is kept in place by positioning forces that resist centrifugal accelerations of up to 150 g. The lipid globules possess an average diameter of 2 to 2.5 m and a density of 0.791 g cm^–3, which is below that of typical plant oleosomes. The potential energy which is generated by the buoyancy of a CLG of 100 globules is in the order of 10^-17 to 10^-16 J, which is 4 to 5 orders of magnitude above thermal noise. The formation of lipid globules can be supressed by raising stage-1 sporangiophores for 24 hs at 5°C. Sporangiophores with a reduced number of lipid globules display gravitropic bending angles that are 3 to 4 times smaller than those of sporangiophores with the normal number of lipid globules. The results suggest that the lipid globules function as gravisusceptors of Phycomyces and that buoyancy is the physical principle for their mode of action. The globules contain -carotene and two distinct fluorescing pigments that are, however, dispensible for graviperception.Abbreviations CLG complex of lipid globules     

Statistical Description of Fat and Meat Phases of Sausages by the Use of Lineal-Path Distribution Function

Morphological characteristics of fat and meat phases of Milano, Felino and Napoli type sausages were statistically described by calculating the lineal-path distribution function [L(z)] from 2D images. The algorithm was able to extract L(z) function with high accuracy. Although Milano and Felino sausages showed similar mass fraction of fat, the probabilities to find a segment of length ??5?mm completely in the fat globules were significantly different. Milano sausages were characterized by the smallest flat globules separated among them by the smallest meat elements. Napoli type sausages resulted to be characterized from fat globules with a very high dimensional inhomogeneity; in fact L ¹ (z) values were not statistically different from Felino type sausages. Nevertheless, the probability to find two fat globules separated from a meat element was greater than those of Milano and Felino samples for any z values.     

High-Resolution Crystal Structure of Spectrin SH3 Domain Fused with a Proline-Rich Peptide

Abstract

A new chimeric protein, named WT-CIIA, was designed by connecting the proline-rich decapeptide PPPVPPYSAG to the C-terminus of the alpha-spectrin SH3 domain through a natural twelve-residue linker to obtain a single-chain model that would imitate intramolecular SH3-ligand interaction. The crystal structure of this fusion protein was determined at 1.7 Å resolution. The asymmetric unit of the crystal contained two SH3 globules contacting with one PPPVPPY fragment located between them. The domains are related by the twofold non-crystallographic axis and the ligand lies in two opposite orientations with respect to the conservative binding sites of SH3 domains.     

Cytinus hypocistis L. embryogenesis: Some biological and ultrastructural aspects of fertilization and embryo development

Abstract

The present paper examines some biological and ultrastructural aspects of fertilization and early development of the embryo in Cytinus hypocistis, a parasitic plant belonging to the Rafflesiaceae. The probable functions of a mucilaginous substance contained in the ovary and embedding the numerous pollen tubes coming from the style are discussed.

It was ascertained that pollen tubes pass through the micropyle and enter a synergid pushing, their way through the nucellar cells that show swollen walls owing to a probable enzymatic action whose function is to facilitate pollen tube penetration. It was hypothesized that the secretion of such enzymes is attributable to the numerous pollen present in the ovary or entering the mycropyle.

Since, in all the ovules observed, synergid degeneration was never found before the arrival of the pollen tube, this degeneration was interpreted as being caused by the material disharged by the pollen tube, rather than being an essential prerequisite for pollen tube penetration into the synergid.

Pollen tube content was observed to be made up of an intensely electron-dense substance surrounding many lipidic globules and numerous polysaccharide vesicles that fuse with the pollen tube wall, clearly contributing to its growth.

The sequence of the first divisions of the developing embryo was followed and the extreme reduction of the embryo is confirmed.

In Cytinus hypocistis starch is totally absent from all the sells belonging to the female gamethophyte as well as to those belonging to the embryo, but lipidic globules are very frequent; it is therefore supposed that these bodies constitute good material for the nutrition of the zygote and early embryo.     

LOW RESISTANCE JUNCTIONS IN CRAYFISH : I. Two Arrays of Globules in Junctional Membranes

The ultrastructure of low resistance junctions between segments of lateral giant fibers in crayfish is studied in sections from specimens fixed either by conventional methods or by glutaraldehyde-H₂O₂ or by glutaraldehyde-lanthanum. Cross sections through junctions fixed by conventional glutaraldehyde display the usual trilaminar profile of two parallel membranes separated by a narrow gap. Most of the junctional regions appear covered by 500–800 Å vesicles which lie on both sides of the junction in rows adjacent to the membranes. Gross sections through junctions fixed by glutaraldehyde-H₂O₂ display, in regions containing vesicles, membranes with a beaded profile. The beads correspond to globules ~125 Å in width and ~170 Å in height arranged in a hexagonal pattern with a unit cell of ~200 Å. The globules of one membrane match precisely with those of the adjacent membrane, and opposite globules seem to come in contact with each other at the center of the junction. The membrane of the vesicles also contains globules. Occasionally the globules of the vesicles seem to join with those of the junctional membranes, apparently forming intracellular junctions. Injunctions negatively stained by lanthanum the globules are seen organized into two arrangements. Areas containing globules in a hexagonal array with a unit cell of ~200 Å (swollen pattern) are seen adjacent to areas in which the globules are more closely and disorderly packed (close packing), the minimum center-to-center distance between adjacent globules being ~125 Å. At higher magnification each globule appears composed of six subunits arranged in a circle around a central region occupied by lanthanum (possibly a pit).     

Synthesis and DNA Binding Properties of a New Benzo[f]Imidazo[1,5b]-Isoquinoline-Butan-1,2-Diol Derivative

A benzo[f]imidazo[1,5b]-isoquinoline derivative 4 with a 1,2-butandiol linker was prepared by reaction of a trimethylsilylated 5-naphthylidenehydantoin 3 with a 2,3-dideoxy-D-glycero-pentafuranoside 2 in 22% yield. After deprotection, the resulting compound 5 was converted to a DMT protected phosphoramidite building block 7 for standard DNA synthesis. DNA/DNA, DNA/RNA duplexes with 5 inserted as bulges were destabilized, except when the new amidite was used for the synthesis of a zipping duplex.     

Bulky DNA adduct levels in normal-appearing colon mucosa,and the prevalence of colorectal adenomas

Abstract

Purpose: Examine the association between bulky DNA adduct levels in colon mucosa and colorectal adenoma prevalence, and explore the correlation between adduct levels in leukocytes and colon tissue.

Methods: Bulky DNA adduct levels were measured using ³²P-postlabelling in biopsies of normal-appearing colon tissue and blood donated by 202 patients. Multivariable logistic regression was used to examine associations between DNA adducts, and interactions of DNA adduct-DNA repair polymorphisms, with the prevalence of colorectal adenomas. Correlation between blood and tissue levels of DNA adducts was evaluated using Spearman’s correlation coefficient.

Results: An interaction between bulky DNA adduct levels and XPA rs1800975 on prevalence of colorectal adenoma was observed. Among individuals with lower DNA repair activity, increased DNA adduct levels were associated with increased colorectal adenoma prevalence (OR?=?1.41 per SD increase, 95%CI: 0.92–2.18). Conversely, among individuals with normal DNA activity, an inverse association was observed (OR?=?0.60 per SD increase, 95%CI: 0.34–1.07). Blood and colon DNA adduct levels were inversely correlated (ρ?=??0.20).

Conclusions: Among genetically susceptible individuals, higher bulky DNA adducts in the colon was associated with the prevalence of colorectal adenomas. The inverse correlation between blood and colon tissue measures demonstrates the importance of quantifying biomarkers in target tissues.     

Isolation and Characterization of Carotenoid-rich Lipid Globules from Peridinium foliaceum

Carotenoid-rich oil globules were isolated from the cytoplasm of the binucleate dinoflagellate, Peridinium foliaceum. These orange globules were collected from ruptured cells by ultracentrifugation on a sucrose density gradient, and checked for purity by electron microscopy. The osmiophilic globules were assayed for lipid (including pigment) and protein content. The lipid to protein ratio was 1.39:1, with a calculated density of the globules of 1.05 grams per cubic centimeter. The lipids were composed of hydrocarbon, wax ester (phytyl ester), triglyceride, and polar (no phospholipid) fractions. The biochemical composition indicated that the globules function as a reservoir of energy-rich components in the cell. Microspectrophotometric observations were consistent with pigment analyses which demonstrated that the globules were carotenoid-rich. In addition to β-carotene, γ-carotene, and canthaxanthin, the carotenogenic precursors: phytoene, phytofluence, ζ-carotene and β-zeacarotene were isolated from the globules. Corrected fluorescence maxima of phytoene and phytofluene in hexane were recorded at 340 and 490 nanometers, respectively. Carotenes constituted 3.3% of the total oil globule lipid. The possibility of an extraplastidic carotenogenic enzyme system in P. foliaceum is discussed.     

Synthesis,characterization and DNA binding and cleavage properties of ruthenium(II) complexes with various polypyridyls

Polypyridyl chlororuthenium(II) complexes have been synthesized and characterized. The binding mode of the complexes to DNA has been evaluated from the combined results of electronic absorption spectroscopy and viscosity measurement study. The results suggest that complexes 1, 2 and 3 bind to DNA via classical intercalation, electrostatic interaction and partial intercalation mode, respectively. Complex 2 shows less affinity for DNA. Cleavage of pUC19 DNA by complexes has been checked using gel electrophoresis. The data disclose that complex 1 has the highest cleaving ability.     

Sulfolobus acidocaldarius DNA聚合酶IV跨越损伤合成能力的酶学特征

[目的]以嗜酸嗜热硫化叶菌Sulfolobus acidocaldarius的DNA聚合酶IV （Saci_0554）为例,表征其跨越模板上损伤碱基的DNA合成效果。[方法]将DNA聚合酶IV （SacpolIV）在大肠杆菌中进行重组表达,经亲和层析纯化得到SacpolIV蛋白;利用人工合成的带有不同损伤的寡核苷酸片段作为模板DNA,用尿素变性聚丙烯酰胺凝胶电泳技术,鉴定SacpolIV在体外跨越各种损伤碱基进行跨损伤合成的催化能力。[结果]SacpolIV重组蛋白能够不同程度地跨越嘌呤和嘧啶损伤,跨越能力的高低取决于损伤碱基与正常碱基形成氢键的能力。本研究还发现,SacpolIV能够在DNA链中掺入核糖核苷酸,但掺入核糖核苷酸的效率低于脱氧核糖核苷酸。[结论]本研究证实SacpolIV具有很强的跨越损伤合成能力,能够跨越多种氢键配对能力减弱的损伤碱基,为其在细胞内的跨越损伤合成功能提供了生化证据。     

Origin and destination of globules and irregular masses in the gonadotropin cells from the pituitary of the African catfish,Clarias gariepinus: a morphological study

The possible function of globules and irregular membrane-bound masses in the gonadotropin cells of the pituitary of Clarias gariepinus was studied. Strong secretory stimulation led to the disappearance of the secretory granules from gonadotropin cells but globules and irregular masses remained present. Acid phosphatase was detected enzyme-cytochemically in both globules and irregular masses. Radiolabelling with tritiated amino acids followed by autoradiography demonstrated that globules received radioactive material after secretory granules. The latter received radioactive material within 75 min of administration of radioactive amino acids but globules and irregular masses did not. Although some globules became radioactively labelled within 24 h of the administration of radioactive amino acids, irregular masses remained unlabelled during this period. Secretory granules reacted positively with antisera against and gonadotropin subunits, whereas globules and irregular masses only reacted with the antiserum against the subunit. A moderate anti-7B2 immunoreactivity was demonstrated in secretory granules and globules, whereas irregular masses labelled strongly. The combined cytological results indicate that globules and irregular masses are degradative, possibly crinophagic structures which develop by fusional events from secretory granules to globules and then to irregular masses.     

The identification of fish eggs of two species,the ovate sole Solea ovata and black porgy Acanthopagrus schlegelii

Fish eggs of the ovate sole Solea ovata and black porgy Acanthopagrus schlegelii were identified through DNA barcoding of cytochrome c oxidase subunit I (COX1). Visual taxonomic features were achieved, and photographs of the eggs of both species at different developmental stages were reported for the first time. In addition, the dissolution of oil globules caused by ethanol as egg fixatives was observed. This result showed the importance of using formalin as egg fixatives in the case of morphometric analysis and the necessity of combining molecular and visual taxonomic method for morphological study.     

Periodicity of DNA in exons

Background  

The periodic pattern of DNA in exons is a known phenomenon. It was suggested that one of the initial causes of periodicity could be the universal (RNY) _n pattern (R = A or G, Y = C or U, N = any base) of ancient RNA. Two major questions were addressed in this paper. Firstly, the cause of DNA periodicity, which was investigated by comparisons between real and simulated coding sequences. Secondly, quantification of DNA periodicity was made using an evolutionary algorithm, which was not previously used for such purposes.     

DNA sequence-specific ligands: XIV. Synthesis of fluorescent biologically active dimeric bisbenzimidazoles DB(3, 4, 5, 7, 11)

Five fluorescent symmetrical dimeric bisbenzimidazoles DB(n) containing four 2,6-substituted benzimidazole cores and differing in the length of the oligomethylene linker between two bisbenzimidazole rings (n = 3, 4, 5, 7, 11) have been synthesized. The ability of the dimeric bisbenzimidazoles to form complexes with the double-stranded DNA has been shown by spectral methods. Upon binding to the double-stranded DNA, DB(n) are localized in the narrow groove. The data on the inhibition of the DNA methyltransferase Dnmt3a by DB(n) indicate that dimeric bisbenzimidazoles DB(3) and DB(11) site-specifically bind to the oligonucleotide duplex.     

ACCUMULATION OF β-CAROTENE IN HALOTOLERANT ALGE: PURIFICATION AND CHARACTERIZATION OF β-CAROTENE-RICH GLOBULES FROM DUNALIELLA BARDAWIL (CHLOROPHYCEAE)1

Dunaliella bardawil Ben-Amotz & Avron, but not most other Dunaliella species, has a unique property of being able to accumulate, in addition to glycerol, large amounts of β-carotene when cultivated under appropriate conditions. These include high light intensity, a high sodium chloride concentration, nitrate deficiency and extreme temperatures. Under conditions of maximal carotene accumulation D. bardawil contains at least 8% of its dry weight as β-carotene while D. salina grown under similar conditions contains only about 0.3%. Electron micrographs of D. bardawil grown under conditions of high β-carotene accumulation show many β-carotene containing globules located in the interthylakoid spaces of the chloroplast. The same algae grown under conditions where β-carotene does not accumulate, contain few to no β-carotene globules. The β-carotene-rich globules were released from the algae into an aqueous medium by a two-stage osmotic shock technique and further purified by centrifugal ion on 10% sucrose. The isolated purified globules were shown by electron microscopy to be free of significant contamination and composed of membrane-free osmiophilic droplets with an average diameter of 150 nm. Reversed phase high performance liquid chromatography of a total pigment extract of the cells revealed the presence of β-carotene as the major pigment, together with chlorophylls a and b, α-carotene and the xanthophylls lutein, neoxauthin and zeaxanthin. β-Carotene accounted for essentially all the pigment in the purified globules. Analysis of the algal and globule β-carotene fractions by HPLC showed that the β-carotene was composed of approximately equal amounts of all-trans β-carotene and of its 9-cis isomer. Intact D. bardawil cells contained on a dry weight basis about 30% glycerol, 30% protein, 18% lipid, 11% carbohydrate, 9%β-carotene and 1% chlorophyll. The β-carotene globules were composed of practically only neutral lipids, more than half of which was β-carotene. It is suggested that the β-carotene globules may serve to protect D. bardawil against injury by the high intensity irradiation to which this alga is usually exposed in nature.     

Optimization of DNA delivery by three classes of hybrid nanoparticle/DNA complexes

Plasmid DNA encoding a luciferase reporter gene was complexed with each of six different hybrid nanoparticles (NPs) synthesized from mixtures of poly (D, L-lactide-co-glycolide acid) (PLGA 50:50) and the cationic lipids DOTAP (1, 2-Dioleoyl-3-Trimethyammonium-Propane) or DC-Chol {3β-[N-(N', N'-Dimethylaminoethane)-carbamyl] Cholesterol}. Particles were 100-400 nm in diameter and the resulting complexes had DNA adsorbed on the surface (out), encapsulated (in), or DNA adsorbed and encapsulated (both). A luciferase reporter assay was used to quantify DNA expression in 293 cells for the uptake of six different NP/DNA complexes. Optimal DNA delivery occurred for 10⁵ cells over a range of 500 ng - 10 μg of NPs containing 20-30 μg DNA per 1 mg of NPs. Uptake of DNA from NP/DNA complexes was found to be 500-600 times as efficient as unbound DNA. Regression analysis was performed and lines were drawn for DNA uptake over a four week interval. NP/DNA complexes with adsorbed NPs (out) showed a large initial uptake followed by a steep slope of DNA decline and large angle of declination; lines from uptake of adsorbed and encapsulated NPs (both) also exhibited a large initial uptake but was followed by a gradual slope of DNA decline and small angle of declination, indicating longer times of luciferase expression in 293 cells. NPs with encapsulated DNA only (in), gave an intermediate activity. The latter two effects were best seen with DOTAP-NPs while the former was best seen with DC-Chol-NPs. These results provide optimal conditions for using different hybrid NP/DNA complexes in vitro and in the future, will be tested in vivo.