ATPase Activity in Flagella from Euglena gracilis. Localization of the Enzyme and Effects of Detergents*

SYNOPSIS. The biochemical effects of some detergents on the ATPase activity of isolated flagella from Euglena gracilis are related to morphologic obliterations induced by those detergents. Enzymic activity can be localized by electron microscopy along the microtubules and also on the paraflagellar rod. The nonionic detergent digitonin solubilizes the enzyme linked to dyneinic arms, whereas the activity linked to residual structures appears enhanced. These results support the hypothesis that the paraflagellar rod may be a structure actively related to the motility of this type of flagellum.     

Light and Electron Microscope Study of Dunaliella primolecta Butcher (Volvocida)*

SYNOPSIS. Light and electron microscope observations on Dunaliella primolecta Butcher from logarithmic and stationary phases of batch cultures are correlated. Except for the lack of a cell wall the fine structure has typical volvocid features. The transition from logarithmic to stationary phase is marked by changes in content and size of cytoplasmic vacuoles, accumulation of cytoplasmic lipid, accumulation of starch in the plastid matrix, and by the formation of autophagosome-like bodies. The organelles in stationary-phase flagellates are closely packed together because of the cytoplasmic lipid and starch-distended chloroplast. Organisms from logarithmic phase have an abundant ribosome-packed groundplasm supporting the organelles. In the cytochemical demonstration of acid phosphatase activity, Golgi cisternae and smooth and coated Golgi vesicles contain Gomori reaction product. The possible roles of the Golgi apparatus in this flagellate are discussed.     

ROLE OF GOLGI APPARATUS IN MUCILAGE PRODUCTION AND CYST FORMATION IN EUGLENA GRACILIS (EUGLENOPHYCEAE)1

Dark grown cells of Euglena gracilis Klebs (strain Z Pringsheim) encyst when placed in minus nitrogen media for 48–72 h in the dark. The number of cisternae per dictyosome decreases from 10–20 to 6–12 during encystment. Cisternae dilate and fill with mucilage within 12–18 h after induction. The material is secreted into the reservoir and deposited onto the cell surface. The encysting cells rotate as they develop resulting in the deposition of a thick mucilaginous layer over the cell surface. The secretion product has been identified as polysaccharide with the periodic acid-silver methenamine reaction. Mucilage has not been observed in the endoplasmic reticulum adjacent to the pellicle. The product present in the dictyosornes and on the cell surface react identically to the silver reagent.     

STRUCTURE OF THE ANISOGAMETES OF THE GREEN SIPHON PSEUDOBRYOPSIS SP. (CHLOROPHYTA)1

The fine structure of the male and female gametes of Pseudobryopsis, particularly that of the flagellar apparatus, is compared with that of swarmers of other green algae. There is general similarity, with differences in detail, to the Ulvales and other green siphons that have been studied. The similarities include overlapping basal bodies, the capping plate type of connective between basal bodies, terminal caps, and system II fibrous roots (rhizoplasts). The capping plate of the female gamete differs from that in other green siphons and the Ulvales in form and in the presence of a faint striation. A diagram illustrating the actual arrangement of the components of the flagellar apparatus is given, along with a discussion of the fact that the mirror image of the true arrangement has been given in some reports on ulvaphycean algae.     

Temperature Effect on the Photo-Accumulation and Phobic Response of Volvox aureus*

SYNOPSIS. The effect of temperature on photoaccumulation and photophobic response of Volvox aureus were studied. The algae exhibited positive photoaccumulation at room temperature and negative at low temperature. When stimulated with light of intermediate intensiy (～ 5 × 10³ lux), the phobic response of the algae consisted of a decrease in the frequency or the cessation of flagellar movement in the anterior cells. At room temperature, an increase in light intensity elicited the phobic response, whereas at low temperature a decrease in light intensity was the effective stimulus. The phobic response lasted only a few seconds. The positive and negative photoaccumulations of the algae could be explained by the brief cessation of flagellar movement in the anterior cells, elicited by an increase of stimulus light at room temperature or a decrease of stimulus at low temperature.     

The Use of the Ex Vivo Chandler Loop Apparatus to Assess the Biocompatibility of Modified Polymeric Blood Conduits

The foreign body reaction occurs when a synthetic surface is introduced to the body. It is characterized by adsorption of blood proteins and the subsequent attachment and activation of platelets, monocyte/macrophage adhesion, and inflammatory cell signaling events, leading to post-procedural complications. The Chandler Loop Apparatus is an experimental system that allows researchers to study the molecular and cellular interactions that occur when large volumes of blood are perfused over polymeric conduits. To that end, this apparatus has been used as an ex vivo model allowing the assessment of the anti-inflammatory properties of various polymer surface modifications. Our laboratory has shown that blood conduits, covalently modified via photoactivation chemistry with recombinant CD47, can confer biocompatibility to polymeric surfaces. Appending CD47 to polymeric surfaces could be an effective means to promote the efficacy of polymeric blood conduits. Herein is the methodology detailing the photoactivation chemistry used to append recombinant CD47 to clinically relevant polymeric blood conduits and the use of the Chandler Loop as an ex vivo experimental model to examine blood interactions with the CD47 modified and control conduits.     

叉蕨科30种植物叶表皮形态特征研究

利用光镜对叉蕨科7属30种植物叶表皮形态特征进行详细观察研究。结果显示：（1）叉蕨科30种植物的叶上表皮和下表皮细胞形状均为不规则型,垂周壁式样为深波状或浅波状,具单晶或针晶;上表皮细胞的长宽比为1.62~4.0,下表皮细胞的长宽比为1.63~3.06。（2）在30种植物中共观察到7种气孔器类型,分别为：极细胞型、腋下细胞型、聚合极细胞型、聚腋下细胞型、不等细胞型、无规则四细胞型和不规则型,每种植物分别具有4~7种气孔器类型,均为下生型气孔;气孔长宽比为1.22~1.91,气孔密度为8~76个/mm²,气孔指数为3.9%~25.7%。（3）基于气孔器类型组成进行聚类分析,可将30种植物分成3个类群。（4）对叶表皮形态特征分析认为,轴脉蕨属应介于叉蕨属和肋毛蕨属之间,且与叉蕨属关系更近;叉蕨属的范畴还有待进一步研究;支持将肋毛蕨属从叉蕨科中分离出来置于鳞毛蕨科,但不支持黄腺羽蕨属归入鳞毛蕨科。     

The usefulness of the chlorophyll fluorescence parameters in harvest prediction in 10 genotypes of winter triticale under optimal growth conditions

The aim of the experiment was to detect differences in the activity of the photosynthetic apparatus in 10 genotypes of winter triticale. Measurements of gas exchange and chlorophyll fluorescence were performed. Among the tested genotypes, the photosynthetic apparatus of Timbo and Piano was the most active, while the photosynthesis of both Babor and Boreas was highly reduced. Additionally, we have found significant correlations between the yield and some parameters of chlorophyll fluorescence and leaf gas exchange. Parameters of chlorophyll fluorescence are useful for estimation of the functional state of the photosynthetic apparatus and could become selection criteria in plant breeding. Moreover, such parameters permit definition of the effectiveness of the utilization of chlorophyll a excitation energy and co‐operation of the light phase reactions, with reactions occurring during the dark phase of photosynthesis.     

Comparative morphology of selected characters of the Pentatomidae foreleg (Hemiptera,Heteroptera)

Heteropteran legs are very diverse within and among taxa, and such variation is frequently correlated with life habits. Structural modifications are commonly present in the legs of the Pentatomoidea but are poorly studied. Using scanning electron microscopy, the tibia and pretarsal microstructure of 82 species of Pentatomidae (Heteroptera), three species of Scutelleridae, and ten species of Thyreocoridae were described, focusing on the pretarsal structure, the foretibial apparatus, and the foretibial comb. The Pentatomidae, the Scutelleridae, and the Thyreocoridae have uniform pretarsal structures. Variation can be found in the length of the parempodial setae and in the shape of the parempodial projections. The foretibial combs of the Pentatomidae, the Thyreocoridae, and the Scutelleridae are described for the first time, and we have demonstrated that there is low structural variation in the foretibial comb complex of the studied species. The setae organization and distribution on the foretibial apparatus is uniform in the families studied. However, the Asopinae (Pentatomidae) bear a foretibial apparatus that is uniquely organized. The taxonomic and phylogenetic relevance of the pretarsal traits, the foretibial apparatus, and the foretibial comb are discussed.     

Surfactant phospholipid metabolism

Pulmonary surfactant is essential for life and is composed of a complex lipoprotein-like mixture that lines the inner surface of the lung to prevent alveolar collapse at the end of expiration. The molecular composition of surfactant depends on highly integrated and regulated processes involving its biosynthesis, remodeling, degradation, and intracellular trafficking. Despite its multicomponent composition, the study of surfactant phospholipid metabolism has focused on two predominant components, disaturated phosphatidylcholine that confers surface-tension lowering activities, and phosphatidylglycerol, recently implicated in innate immune defense. Future studies providing a better understanding of the molecular control and physiological relevance of minor surfactant lipid components are needed. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.