Feeding of piscivorous Japanese Spanish mackerel juveniles on larvae with an elongate and laterally compressed body

Scomberomorus niphonius juveniles were fed with alternative prey differing in body shape: elongate and laterally compressed (clupeid or gobiid larvae) and deep‐framed bodies (paralichthyid larvae) in aquaria. The ratio of prey larvae with elongate and laterally compressed body: prey larvae with deep‐framed body in the aquaria was 1 : 1. The juveniles fed almost exclusively on the larvae with an elongate and laterally compressed body.     

The saurian malarias of Venezuela: Haemosporidian parasites of gekkonid lizards

Telford S. P., Jr. 1978. The saurian malarias of Venezuela: haemosporidian parasites of gekkonid lizards. International Journal for Parasitology8: 341–353. Five haemosporidian species were found among 185 gekkonid lizards from Estados Portuguesa, Cojedes and Aragua, Venezuela, four of which were new to science. A pigmented Plasmodium species is described from Gonatodes taniae of Estado Aragua. It produces 8–20 merozoites in variably shaped schizonts, and elongate, irregularly margined prematuration gametocytes which contract to form round to broadly elongate mature gametocytes. Phyllodactylus ventralis of Estado Portuguesa is parasitized by two new unpigmented malarial species. One produces 11–35 merozoites in schizonts which are often rounded or elongated, occasionally fan-shaped. Gametocytes are always elongated and usually lie diagonally across one end of the host cell or laterally to the nucleus. The second species forms rounded mature schizonts nearly filled with 14–32 merozoites. The sexual stages are usually round or oval, rarely elongate. Plasmodium aurulentum Telford, 1971 was found in Thecadactylus raplcaudus of Estados Portuguesa and Cojedes. A single Thecadactylus from Cojedes was infected by a haemosporidian species of uncertain generic identity which resembles a parasite found earlier in a Panamanian gecko.     

Vascular endothelial cells minimize the total force on their nuclei

The vascular endothelium is a cellular monolayer that lines the arterial walls. It plays a vital role in the initiation and development of atherosclerosis, an occlusive arterial disease responsible for 50% of deaths in the Western world. The focal nature of the disease suggests that hemodynamic forces are an important factor in its pathogenesis. This has led to the investigation of the effects of mechanical forces on the endothelial cells themselves. It has been found that endothelial cells do respond to stresses induced by the flowing blood; in particular, they elongate and align with an imposed flow direction. In this paper, we calculate the distribution of force exerted on a three-dimensional hump, representing the raised cell nucleus, by a uniform shear flow. It is found that, for a nonaxisymmetric ellipsoidal hump, the least total force is experienced when the hump is aligned with the flow. Furthermore, for a hump of fixed volume, there is a specific aspect ratio combination that results in the least total force upon the hump, (0.38:2.2:1.0; height:length:width). This is approximately the same as the average aspect ratio taken up by the cell nuclei in vivo (0.27:2.23:1.0). It is possible, therefore, that the cells respond to the flow in such a way as to minimize the total force on their nuclei.     

Likelihood ratio tests for a mixture of two von Mises distributions

It is proposed that the orientation of elongate objects, such as bones, may be used to identify the flow direction of ancient river deposits. If true, elongate objects could be of great value when ancient bedforms such as ripples and dunes are not visible. Two sandstone quarries were investigated wherein the paleoflow direction was determined from both bedforms and elongate dinosaur bones. A mixture of two von Mises distributions captures the observation that elongate bones transported under unidirectional flow conditions will align both parallel and perpendicular to the flow direction. Likelihood ratio tests for a mixture of two von Mises distributions are given. The power of these tests is investigated by simulation since the direction of dinosaur bones agrees with the primary bedforms if the hypothesis test comparing the dominant mean direction of the bones to the paleoflow direction fails to reject. The likelihood ratio test on the dominant mean direction has reasonable power. If the two mean directions in the mixture distribution are pi apart, a more powerful likelihood ratio test can be used. The likelihood ratio test on the hypothesis that the two mean directions are exactly pi apart is useful in determining if the assumptions of the more powerful test are satisfied.     

A new species of the genusProbstmayria Ransom, 1907 (Nematoda: Atractidae) from the rhesus macaque,Macaca mulatta

Probstmayria nainitalensis n. sp. is described from the rectum of the rhesus macaque,Macaca mulatta, from Nainital, India. The new form consists of morphologically dissimilar spicules, spicular ratio 1:1.41–1.50, tip of shorter spicule elongate and blunt, six pairs of postanal papillae and a prominent gubernaculum in the male and didelphic ovaries and postequatorial vulva in the female. A key to the species is also furnished.     

The importance of anatomical structural study of roots for the understanding of physiological processes

Abstract

Besides being species‐specific, the inner structure of the root is influenced by the place and time of origin during the growth period. From the root tip up to the base of a particular root, the zones of cell division, cell elongation, formation of root hairs and root branching can be distinguished. The root tip that is covered by a root cap and mucilage is protected against evaporation and water contact. From the end of the lateral parts of the root cap, the cells become exposed to the surrounding environment. The cells can elongate by water uptake or can shrink by water loss. All processes of geotropic growth take place there. In this study, some differences are illustrated using Zea mays plants. Radicle and roots emerging from several nodes of the shoot as well as lateral roots are compared. The distances from the tip and from the base of the root are also very important for characterization of particular root functions. Distinctive features such as root diameter, size of the stele and of the cortex, ratio of cortex to stele, number and width of the xylem vessels, size of cells, special thickenings and stage of lignification as well as symptoms of maturation are observed.     

Granule cell induction of 9-O-acetyl gangliosides on cerebellar glia in microcultures

In previous studies we have shown that the expression of acetylated gangliosides recognized by the JONES monoclonal antibody is correlated with regions of cell migration in the developing rat nervous system. In this study we have investigated the expression of these gangliosides in two different types of cultures prepared from dissociated postnatal rat cerebella. In the first type, cells are plated after dissociation under conditions where most of the glial cells develop a stellate morphology that anchors neurons but does not support their migration. In the second type of culture, cells are plated in a ratio of four neurons to one glial cell and under these conditions the predominant form of astroglia is an elongate form that supports the migration of granule neurons. Granule neurons express JONES antigens in dissociated cell suspensions and in cultures in which cells are plated either after dissociation or in a 4:1 neuron:glia ratio. On the other hand, glial cells grown in the absence of neurons are JONES negative. In addition, the expression of JONES gangliosides by glial cells is different in the two types of culture. In cultures where the astroglial cells display the stellate morphology only a small proportion show JONES staining. Cultures in which the glial cells assume the elongate morphology have a significantly higher number of JONES-positive astroglia.     

Characterization of normal spermiation and spermiation failure induced by hormone suppression in adult rats

At the end of spermatogenesis, elongated spermatids are released from supporting Sertoli cells via the process termed spermiation. Previous studies have shown that spermiation failure occurs after hormone suppression, in which spermatids are retained instead of releasing. However, the molecular mechanisms involved in spermiation and spermiation failure are largely unknown. The aims of the present study were, first, to characterize the ultrastructural events associated with normal spermiation and spermiation failure using light and electron microscopy and, second, to investigate the localization of cell adhesion-associated (beta1-integrin and cadherins) and junction-associated molecules (integrin-associated kinase [ILK], beta-catenin, and espin) during these processes. Four adult Sprague-Dawley rats received testosterone and estradiol implants and FSH antibody (2 mg kg-1 day-1) for 7 days to suppress testicular testosterone and FSH and to induce spermiation failure. Four rats treated with saline were used as controls. After testosterone and FSH suppression, spermiation at the ultrastructural level appeared to be normal until the final disengagement of the spermatids from Sertoli cells (stage VIII), at which stage a large number of retained spermatids were noted. Immunohistochemical localization of espin showed that during spermiation, removal of the ectoplasmic specialization (ES) occurred 30 h before spermatid disengagement, suggesting that non-ES junctions mediate the spermatid-Sertoli cell interaction before and during disengagement. beta1-Integrin and beta-catenin remained associated with spermatids after ES removal and until disengagement; however, ILK was removed along with the ES. Though detectable, N-cadherin was not associated with the spermatid-Sertoli cell junction. After testosterone and FSH suppression, beta1-integrin, but not N-cadherin or beta-catenin, remained associated with spermatids that failed to spermiate. In conclusion, hormone suppression-induced spermiation failure is caused by defects in the disengagement of spermatids from the Sertoli cell, and this process likely is mediated by beta1-integrin in an ILK-independent mechanism.     

Hemicelluloses of cell walls of a proso millet cell suspension culture

Cell wall composition of a stable suspension of proso millet (Panicum miliaceum L. cv Abarr) cells is similar to those of tissues and cell suspensions of other graminaceous species. Extraction of hemicelluloses with step-wise increasing concentrations of alkali yields materials that, like those of embryonal cells of maize coleoptiles, comprise mostly glucuronoarabinoxylan, xyloglucan, and small amounts of (1-3),(1-4)-β-d-glucan. As in the walls of embryonal cells of the maize coleoptile, 5-arabinosyl and 3-arabinosyl comprise much higher proportions of the total hemicellulosic sugars than in walls of developed or elongated cells. Unlike cells of many dicotyledonous species, millet cells do not elongate or undergo observable differentiation during the stationary phase of culture, and consequently, their wall composition is remarkably consistent throughout the culture cycle. The proso millet cell suspension culture constitutes a reasonable model for study of cell wall biogenesis in embryonal cells of a graminaceous species, but because of marked changes in the composition of hemicelluloses in these species during cell enlargement, additional model systems should be sought.     

XYLEM ANATOMY AND HYDRAULIC CONDUCTANCE OF COSTA RICAN BLECHNUM FERNS

Hydraulic conductivities of stems, stipes, and elongate leaf stipes were determined for greenhouse-grown Blechnum (B. fraxineum, B. fragile, B. buchtienii, B. sprucei) and Salpichlaena (S. volubilis) plants collected in tropical rain forests of Costa Rica. Organ conductivity was examined in relation to morphology and tracheid characteristics in order to gain an understanding of factors influencing water flow. Hydraulic conductivity of plant organs was determined by measurement of transpiration rates, leaf areas, and water potential gradients. Erect stemmed species develop larger whole plant water potential gradients than elongate stemmed species for a similar transpiration rate. Elongate leaves develop even smaller water potential gradients for a given transpiration rate. Stems have larger hydraulic conductivities but smaller leaf-specific conductivities (LSCs) than stipes. Small conductivities and small LSCs are associated with short, erect stems. Elongate structures have large conductivities and large LSCs. Of the tracheid characteristics examined, the most important characteristics determining the magnitude of organ hydraulic conductivity are diameter, pit aperture area between tracheids, taper length, and cell length. Large conductivities of S. volubilis climbing leaf stipes are associated with very large-diameter tracheids (some > 200 μm), large tracheid number, exceptionally long tracheids (some > 4 cm), large pit aperture area between tracheids, short tracheid taper, and smooth tracheid lumen walls. Hagen-Poiseuille estimates of hydraulic conductivity range from 1.1 to 3.3 times the measured values. Conductivity of stipes is highly correlated with leaf area supplied by stipes. Conductivities of stems and elongate leaf stipes also correlate with leaf area supplied by these structures. Estimated hydraulic conductivities of field-grown Blechnum and Salpichlaena demonstrate that larger conductivities are associated with larger plants. This study contributes toward our knowledge of fern water relations and extends previous growth form/hydraulic architecture characterizations by providing a more comprehensive comparison of closely related species. In addition, this study provides evidence for the relative importance of tracheid characteristics in determining the magnitude of organ hydraulic conductivity.     

Light germination ofAnthoceros miyabeanus spores

The effects of light on the spore germination of a hornwort species,Anthoceros miyabeanus Steph., were investigated. Spores of this species were photoblastic, but their sensitivities to light quality were different. Under either continuous white, red or diffused daylight, more than 80% of the spores germinated, but under blue light none or a few of them germinated. Under continuous far-red light or in total darkness, the spores did not germinate at all.Anthoceros spores required red light irradiation for a very long duration, i.e., over 12–24 hr of red light for saturated germination. However, the spore germination showed clear photo-reversibility by repeated irradiation of red and far-red light. The germination pattern clearly varied with the light quality. There were two fundamental patterns; (1) cell mass type in white or blue light: spores divide before germination, and the sporelings divide frequently and form 1–2 rhizoids soon after germination, and (2) germ tube type in red light: spores germinate without cell division, and the single-cell sporelings elongate without cell division and rhizoid formation.     

A new species of Parspina Pearse, 1920 (Digenea: Cryptogonimidae) from Pimelodella gracilis (Valenciennes) (Siluriformes: Heptapteridae) in the Paraná River basin, Argentina, and a key to the genus

A new species of cryptogonimid belonging to the genus Parspina Pearse, 1920 is described from the intestine of Pimelodella gracilis (Valenciennes) in the Paraná River basin, Argentina. Parspina pimelodellae n. sp. is characterised by having: (i) a body length/width ratio of 1:3.6–5.3 at the level of the ventral sucker; (ii) 21 oral spines; (iii) an oral sucker larger than the ventral sucker, with a sucker width ratio of 1:0.6–0.7; (iv) a postcaecal region of 16–19% of the body-length; (v) a compact, transversely elongate ovary, anterior to and well separated from the testes; (vi) small, branched vitelline follicles, extending from the level of the ventral sucker to the anterior margin of the ovary; and (vii) a large seminal vesicle situated posterodorsal to the ventral sucker. A key to the species of Parspina is presented.     

A new species of Pseudopecoelus von Wicklen, 1946 (Digenea: Opecoelidae) from the orange roughy Hoplostethus atlanticus Collett, 1889 (Trachichthyidae) from off southeastern Australia

A new species, Pseudopecoelus sewelli, is described from the deep-sea fish Hoplostethus atlanticus from off southeastern Australia. It is an elongate form with considerable variation in such important characters as the anterior vitelline extent, the sucker ratio and the egg-size. The features distinguishing this species from five related forms are combinations of the sucker ratio, egg-size, lobation of gonads, presence or absence of a cirrus-sac and the position of the genital pore.     

Ophryoglena hemophaga n. sp. (Ciliophora: Ophryoglenidae): a parasite of the digestive gland of zebra mussels Dreissena polymorpha

Ophryoglena hemophaga n. sp. is described from a freshwater Dreissena polymorpha population in the Rhine delta of the Netherlands. This is the first ophryoglenine species (order Hymenostomatida, suborder Ophryoglenina) recorded as a molluscan parasite. As is typical of ciliates in the suborder Ophryoglenina, O. hemophaga exhibits a polymorphic life history with cystment and reproduction by palintomy. Trophonts were observed within digestive gland lumina, and zebra mussel hemocytes were present in some of their digestive vacuoles. The presence of a single, longitudinal tract of multiple contractile vacuoles represents its most unique feature and distinguishes it from all other described Ophryoglena spp. The number of somatic kineties of O. hemophaga (range 100 to 124) is also distinguishing as it is one of the lowest for [corrected] an Ophryoglena sp. Other characteristics of this species include: ovoid to elongate trophonts 96 to 288 microm in length, with an elongate macronucleus 41 to 65 microm in length; tomonts 50 to 150 microm in diameter producing a clear mucous cyst envelope, whose thickness is approximately half of the tomont diameter; elongated theronts 96 to 131 microm in length which emerge after 1 to 3 cell divisions taking 36 to 48 h at 20 +/- 3 degrees C. Protomonts and theronts are, respectively, negatively and positively phototactic--characteristics that likely aid in maintenance of infection in zebra mussel populations.     

Effekte der Phospholipase D auf den Elektronentransport und die Lipidzusammensetzung isolierter Spinatchloroplasten

Summary The process of cell wall regeneration around two species of higher plant protoplasts has been studied using reflection scanning electron microscopy. The first stage in the process is the formation of short fibres from randomly spaced centres. With protoplasts of tobacco leaf (Nicotiana tabacum L., cv White Burley) these fibres then elongate and interlace apparently at random to give rise to a matted continuous layer of wall. Protoplasts of a suspension culture of grapevine cells (Vitis vinifera L. cv Müller Thurgau) produce short fibres but these fail to elongate. Budding is observed during wall regeneration around vine protoplasts. The results are discussed in terms of the mechanical properties of the wall and its relationship to changes in plasmalemma morphology which are observed during wall formation.Abbreviation SEM scanning electron microscopy     

Characterization of Top Leader Elongation in Nordmann Fir (Abies nordmanniana)

Our understanding of the developmental changes that occur during top leader elongation in gymnosperms lags behind that in angiosperms. We developed a semiquantitative method for determining epidermal cell size, by measuring the Feret diameter after cell wall staining of stem epidermal peels. This method allowed a large number of cells to be measured at various locations in the top leader of the Christmas tree Abies nordmanniana. Further, we have identified the growth rate of individual sections of the top leader, and the relationship between cell length and needle arrangement throughout the top leader. At bud break, all stem units begin to elongate simultaneously, but growth ceases from the base upwards during top leader elongation. Long top leaders were characterized by having up to three times as long cells at the base compared to short top leaders, whereas the cell lengths were similar in the apical region independent of the given plant growth capacity. In the basal sector, the level of auxin was much higher, whereas the levels of cytokinins were lower than in the apical sector, causing the auxin/cytokinin ratio to change from about 3 in the apical sector to more than 20 in the basal part. The Fibonacci number changed in the apical sector due to an increased cell number in the stem units and therefore longer distance between the needles. We conclude that the general growth pattern during top leader elongation in A. nordmanniana is similar to angiosperms but differs at the cellular level.

     

Significance of fresh weight to dry cell weight ratio in plant cell suspension cultures

Summary The ratio of fresh weight to dry cell weight (FW/DCW), an index of cell water content, is important in determining the theoretical maximum cell concentration in high density culture of plant cell suspensions. Theoretical maximum cell density for Thalictrum rugosum was estimated to be as high as 137.2 g/l. The FW/DCW values were found to vary from species to species and it was related to medium osmolarity. When the cells were placed in a high osmolarity environment, decrease of FW/DCW was very rapid, taking place within 24 hours.