Lateral Expansions Research Articles

Effects of jaw adductor hypertrophy on buccal expansions during feeding of air breathing catfishes (Teleostei, Clariidae)

Some species of Clariidae (air breathing cat- fishes) have extremely well developed (hypertrophied) jaw closing muscles that increase the maximal biting force of these species. As these enlarged jaw muscles tightly cover the suspensoria, which are firmly connected to the neurocranium, we expect diminished lateral expansions during suction for species with hypertrophied jaw muscles. In turn, this could imply a reduced suction performance for these species. Compared to Clarias gariepinus, which has relatively small jaw closers, Clariallabes longicauda shows a clear hypertrophy of the jaw adductors. A kinematic analysis of prey capture in these two species is presented here. As predicted, Clariallabes longicauda shows less lateral expansion (average abduction of the hyoids of 19.0�) than Clarias gariepinus (abduction of 31.1�). However, our data indicate that the decrease in lateral expansion capacity in the species with excessive adductor development is compensated for by a larger and faster ventral expansion of the buccal cavity by depression of the hyoid.

Caracteres morfo-anatômicos de folha e caule de Bauhinia microstachya

Bauhinia microstachya (Fabaceae) é um arbusto escandente, de caule comprimido e flexuoso e folhas bilobadas, denominado popularmente de escada-de-macaco e empregado como analgésico na medicina tradicional. A morfo-anatomia foliar e caulinar dessa espécie foi analisada a fim de contribuir com informações farmacognósticas e taxonômicas. O material botânico foi fixado, seccionado e corado com azul de toluidina e com a dupla coloração fucsina básica / azul de astra, bem como submetido a testes histoquímicos. A folha apresenta epiderme uniestratificada, estômatos paracíticos e anomocíticos na face abaxial, tricomas tectores unicelulares, mesofilo dorsiventral e nervura central com feixe vascular colateral único, envolto por bainha esclerenquimática. O caule mostra estrutura atípica característica, devido ao crescimento irregular do câmbio vascular, que é mais ativo em dois lados opostos, determinando expansões laterais. A medula possui forma de cruz, e idioblastos contendo prismas e raras drusas de oxalato de cálcio são observados.

Morphological, anatomical and physiological characteristics of Lathyrus latifolius L. - Fabaceae

The Lathyrus species are wild relatives of cultivated peas. Results of morphological, anatomical and physiological analyses of Lathyrus latifolius L. are presented in this paper. Certain measured parameters and observed morphological characteristics are not in agreement with available literature data, whereas no reference to the winged stem width, length of inflorescence pedicle, calyx length and leaflet index can be found. Two forms, f rotundifolium RCHB and f. latifolius BECK have been determined. Leaflets are amphystomatic, with anisocytic stomata present in almost equal number on both epidermises, dorsoventral, with one-layered palisade and many-layered spongy tissue. Stem in transverse section is rotund to oval with two long lateral wing-like expansions and cortical bundles. Mineral element analysis shows that the highest N, P and K concentrations were obtained with the flower while Ca and Na with the leaf. Leaf pigment content was higher than stem content while net photosynthesis rate was twice as high as respiration rate.

Flow analysis of two-dimensional pulsed jets by particle image velocimetry

A purely alternating jet without mean mass flux and a mixed pulsed jet containing an additional blowing component were investigated by particle image velocimetry (PIV). The jets issued from a two-dimensional slit connected to a converging nozzle, opening normally from a flat wall. The pulsation was driven by a loudspeaker. The mean velocity fields were characterized by the combination of downstream directional blowing and omni-directional suction. The velocity fluctuations were dominated by contra-rotating eddy pairs synchronized with the pulsation and formed at the jet edges during blowing. Phase-synchronized measurements permit the investigation of the averaged patterns and the cycle-to-cycle fluctuations of these vortices. The mean trajectories of vortex centers during a whole injection cycle show how large lateral jet expansions are achieved. For a purely alternating jet, the expansion takes place close to the slit. For a mixed pulsed jet, the vortices develop farther from the orifice. In addition, proper orthogonal mode decomposition demonstrates that only a few modes are required to represent the main events of the flow dynamics.

Morphological, biochemical and molecular characterization of Herpetomonas samuelpessoai camargoi n. subsp., a trypanosomatid isolated from the flower of the squash Cucurbita moschata.

We report the morphological, biochemical and molecular characteristics of a trypanosomatid isolated from the flower of Cucurbita moschata. Although the trypanosomatid was isolated from a plant, the lack of recognition of Phytomonas-specific molecular markers based on spliced-leader and ribosomal genes as well as by monoclonal antibodies specific for Phytomonas argues against assigning it to this genus. Because the isolate displayed typical opisthomastigote forms in culture, it is assigned to the genus Herpetomonas. Analysis of randomly amplified polymorphic DNA (RAPD) patterns and characterization of ribosomal SSU and ITS markers suggest that it is more closely related to H. samuelpessoai than to any other species. However, the presence of spined flagellates in culture (displaying lateral expansions of the plasma membrane originating near the flagellar pocket) and isolate-specific RAPD fingerprints argue strongly that the trypanosomatid belongs to a new subspecies, for which the name Herpetomonas samuelpessoai camargoi n. subsp. is proposed.

Thermal Analysis of Plates with Different Geometry

A detailed analysis of the thermal resistance of a plate is given. The plate sits between a heat source and an extensive heat sink. The thermal resistance strongly depends on the overlap of the plate around the heat source. Another important factor is the coefficient of hear transfer between plate and hear sink (ã). The goal of this article is to find an optimal geometry of the plate so that the sum of thermal resistance of conduction and thermal transfer resistance to the heat sink becomes a minimum.The approach is a practical one where results of measurements are generalized with help of the finite element method (FEW An easy-to-use method for finding ã is presented. ã has a strong influence on the optimal thickness of the plate which makes the thermal resistance minimal for given lateral expansions. The geometry of such a stack can only be optimized for one specific cooling condition.

Osmunda cinnamomea (Osmundaceae) in the Upper Cretaceous of Western North America: Additional Evidence for Exceptional Species Longevity among Filicalean Ferns

The discovery of numerous anatomically preserved fossils in Upper Cretaceous sediments reveals that essentially modern osmundaceous ferns have inhabited southern Alberta, Canada, since the end of the Mesozoic. The Cretaceous fossils consist of small stems that are surrounded by leaf bases and adventitious roots. All of the features of the fossils fall within the ranges of variation for characters of living Osmunda cinnamomea L., and the fossils display all of the specifically diagnostic anatomical characters for this species. These include an ectophloic, dictyoxylic solenostele that lacks leaf gaps in the phloem, C‐shaped frond traces, frond bases with lateral stipular expansions, features of the endodermis, and disposition of sclerenchyma tissues in the stem and frond bases. A reexamination of extant specimens and of previously described fossils from Neogene and Paleocene deposits clarifies the range of variation for specifically diagnostic characters and reveals the more or less continuous presence of O. cinnamomea L. in western North America for at least 70 million years. This article provides an additional example of a well‐characterized fossil filicalean fern that can be confidently assigned to a species with living representatives. It is becoming increasingly clear that species longevity for homosporous pteridophytes can be far greater, and species turnover may be far lower, than expected from evolutionary models developed for flowering plants.

12層T型並列型実験におけるマクロモデルによる解析と並列型の設計用せん断力についての研究 : ハイブリッド構造に関する日米共同構造実験研究 (HWS)

Seismic test on 12-story T-shaped coupled shear walls has been conducted under the U.S.-Japan cooperative structural research project on composite and hybrid structures. The test results showed large differences between carrying shear forces on the tensile side and the compressive side in coupled shear walls through coupling beams. In this paper, we propose macro-modelling with multi-springs for coupled walls and coupling beams, and the results of the simulation for 12-story seismic test approximate to the test results roughly. Then, by estimating lateral expansions of coupled walls, the simulation results are in good agreement with the test ones. Moreover, we propose a simplified calculation method to estimate the shear forces of coupled walls for ultimate design, though usual design is conducted without considering the axial forces of coupling beams and the lateral expansions of coupled walls.

Microanatomy of the hypophyseal fossa boundaries.

The authors studied the heads of 17 adult cadavers and one fetus to clarify the anatomy of the sellar region, particularly the lateral boundaries of the hypophyseal fossa. Vascular injections and microdissection or histological techniques were used in this study. The roof of the cavernous sinuses and diaphragma sellae were part of a single horizontal dural layer that joined the two anterior petroclinoid folds. Laterally, the direction of this layer changed; it became the lateral wall of the cavernous sinus and joined the dura mater of the middle cerebral fossa. On the midline, this layer ballooned toward the sella through the diaphragmatic foramina, created a dural bag containing the hypophysis, and attached to the inferior aspect of the diaphragma sellae. As a consequence, no straight sagittal dural wall existed between the pituitary gland and cavernous sinus; the lateral border of the hypophyseal fossa was part of this anteroposterior and superoinferior convex bag. The authors stress the importance of the venous elements of the region and discuss the structure of the cavernous and coronary sinuses. Invasion of the cavernous sinus makes surgery more risky and difficult and may necessitate modification of the surgical treatment plan. The preoperative diagnosis of cavernous sinus invasion is thus of great interest, but the possibility of normal lateral expansions of the pituitary gland must be kept in mind. A lateral expansion of this gland into the cavernous sinus was encountered in 29% of the specimens, and an adenoma that developed in such an expansion could easily mimic cavernous sinus invasion.

Segmentation of the vertebrate hindbrain: a time-lapse analysis.

The chick hindbrain starts from a simple and relatively uniform axis and becomes segmented into repeating units, called rhombomeres. The rhombomeres become sites of cell differentiation into specific neurons and the location from which neural crest cells emerge from the neural tube to form the peripheral nervous system, which has only been analyzed at distinct time points due to the lack of a method to watch the neural tube as it is shaped into segments. We have developed a whole-embryo explant culture system in order to study cell and tissue movements with time-lapse video microscopy. Quantitative analyses of the neural tube during its segmentation show that not all rhombomeres are shaped by the same mechanism. In the rostral hindbrain, or first three segments, rhombomeres are shaped by an expansion in the lateral width of the mid-rhombomere; either a smaller expansion or a constriction takes place at the rhombomere boundaries. In the caudal hindbrain, the rhombomere boundaries constrict more than the mid-rhombomere lateral widths increase or decrease, leading to the shaping of the segments. Throughout the segmentation process the rostrocaudal lengths of all rhombomeres remain nearly constant indicating that shape changes are influenced by lateral expansions and constrictions of the neural tube.

Female genital structures of Metridinidae (Copepoda: Calanoida)

The female genital structures of six calanoid copepod species, belonging to the genera Gaussia, Metridia and Pleuromamma, were studied using light and scanning electron microscopy (SEM). The copulatory pores and seminal receptacles are paired in Gaussia and Metridia, but unpaired in Pleuromamma. A thin epicuticle and a spermatophoral plug are the mechanisms by which the pores are closed before and after copulation. The pores open directly into the receptacles, which are reduced to shallow integumentary depressions in Gaussia. The mode of insemination suggests two matings in females of Gaussia and Metridia, but only one in Pleuromamma. Paired gonopores and egg-laying ducts are present in the three genera, with a characteristic, closed semicircular configuration; these are opened during egg-laying by the action of retractor muscles of the gonoporal plates. The seminal ducts, which open into the gonopores, are long, thin and paired in Gaussia and Metridia, whereas in Pleuromamma they are short, broad and unpaired. The opening of the seminal and egg-laying ducts is synchronized. The shell ducts are paired in Gaussia and Metridia, unpaired in Pleuromamma; these arise from glands situated in the lateral expansions of the last prosomite and lead into the distal part of each egg-laying duct in Gaussia and Metridia and of the egg-laying duct receiving the seminal duct in Pleuromamma. The position and anatomy of these structures are compared to those of other families and genera, and a functional interpretation of their morphology is proposed. The main evolutionary trends of the different structural patterns of female calanoid genitalia are presented in tabular form.

Relative distribution of rDNA and proteins of the RNA polymerase I transcription machinery at chromosomal NORs.

Using confocal and immunofluorescence microscopy the relative distribution of the ribosomal chromatin and some proteins of the RNA polymerase I transcription machinery such as upstream binding factor (UBF), RNA polymerase I and DNA topoisomerase I was analyzed on chromosomal nucleolus organizer regions (NORs) of PtK1 cells. Staining with various DNA fluorochromes revealed that the ribosomal chromatin may be found at the axial region of the NOR and also at lateral expansions around the axis that can also be detected by in situ hybridization. It was observed that the transcription machinery shows a crescent-shaped distribution around the axial ribosomal chromatin at the NOR of metaphase and anaphase chromatids. An ultrastructural analysis of serially sectioned NORs supports this crescent-shape organization. Taking into account previous and present results and the loop/scaffold model of chromosome structure, we propose a model of NOR organization. The model proposes that ribosomal genes that were inactive in the preceding interphase would be present as condensed short Q-loops occupying the axial region of the NOR. Ribosomal genes previously active during interphase would be undercondensed as large R-loops associated with the transcription machinery, which is distributed in a crescent-shaped fashion around the previously active ribosomal DNA.

Further data on intracellular structures of human salivary glands. A SEM study.

Specimens of human salivary glands have been studied by our modification of the AODO maceration method which, carried out on sections of controlled thickness, allows the analytical study of human bioptical material. Lately, our technique has been further improved and simplified by omitting the treatment with dimethylsulfoxide and by using osmium-ferrocyanide as secondary fixative. Following maceration with diluted OsO4, some of the sections also were shaken for 10-15 min with a rotating agitator. Already at low magnification, all parenchymal cells were clearly distinguishable for their complement of cytoplasmic organelles. Serous cells and mucous cells at the beginning of their secretory cycle were characterized by well developed RER and Golgi apparatus, while mature mucous cells exhibited only scanty organelles compressed among the secretory droplets. Mitochondria were tubular, and often branched and convoluted. When sectioned, these organelles, besides the usual plate-like cristae, showed tubular cristae as well. The SER of striated and excretory duct cells was well developed and consisted of a network of smooth anastomosing tubules in the apical cytoplasm where it probably represented the transcellular pathway for ion transport. In specimens subjected to shaking, cytoplasmic organelles were occasionally removed allowing a nonobstructed view of the inner side of the plasmalemma and its specializations. With this technique the intercellular canaliculi of serous cells also became appreciable from their cytoplasmic side. They appeared as ribbon-like irregular protrusions with walls fenestrated by holes, corresponding to the interior of microvilli deprived of the cytoskeleton, and, sometimes, with lateral expansions possibly related to the mechanism of exocytosis. Results reported here clearly showed the usefulness of the maceration method in providing additional data on the cytoarchitecture of epithelial cells of salivary glands. Furthermore, by allowing the visualization of internal surfaces previously hidden to direct inspection, our technique may open new horizons in morpho/functional studies of human salivary glands.

Patterning in opalinids: II. Endocytofibrillar complex in Protoopalina pseudonutti Sandon, 1976

Summary At certain phases of the life cycle of Protoopalina pseudonutti silver impregnation according to the technique of Fernandez-Galiano reveals a large axial fibrillar complex which divides into numerous lateral branches linked to the falcular zone and the somatic kineties. An electron microscopy study, using a new method of fixation, confirmed the existence of a well-developed fibrillar network composed of microfibrillar bundles with irregularly spaced dense zones. It continues in the falcular matrix and branches extensively, producing lateral expansions, some of which extend along the somatic kineties. Others surround the nuclei which, during interphase and division, also carry a thin microfibrillar layer on the cytoplasmic face of the nuclear envelope. This fibrillar network extends caudally and forms the framework of the tip. In its morphology and ultrastructural organization, this network is similar to certain skeletal constituents observed in ciliates, such as the ecto-endoplasmic boundary of the rumen ciliates. It could thus also be composed of centrin-like proteins and has resemblances to the cortical network which characterizes the species Opalina ranarum. Consequently, it may play a role in cell morphogenesis. Its development, which in some species is more pronounced, and its location varies according to the morphology of the cell and the number of nuclei or both. In species with few nuclei cytoskeletal differentiation is required to control the positioning of the nuclei to ensure the transmission of genetic information.

Three-dimensional organization of the ribosomal genes and Ag-NOR proteins during interphase and mitosis in PtK1 cells studied by confocal microscopy

The three-dimensional (3-D) organization of rDNA-containing chromatin and the set of protein markers of active ribosomal genes, the Ag-NOR proteins, were investigated by confocal laser scanning microscopy (CLSM). The rDNA genes of marsupial cells (PtK1) were mapped using biotinylated DNA probes for 45S rDNA sequences and the Ag-NOR protein distribution was revealed by specific Ag-NOR staining. We used PtK1 cells because each nucleolus possesses only one nucleolar organizer region (NOR). In metaphase chromosomes, nonisotopic in situ hybridization demonstrated the presence of rDNA in the secondary constriction of the X chromosomes with an axial distribution and also lateral expansions. 3-D reconstruction of the Ag-NOR protein signals revealed the presence of these proteins in the secondary constriction where they formed a crescent-shaped structure around the axial chromatin pedicule. The organization of the secondary constriction in PtK1 chromosomes is discussed. During interphase, nonisotopic in situ hybridization in intact cell monolayers and isolated nuclei showed the rDNA genes distributed as intense fluorescent spots linked by weak signals in the inner regions of the nucleoli. We conclude that the rDNA is not homogeneously distributed in the internal regions of the nucleoli. In the same nucleolar regions, the Ag-NOR proteins were revealed as granules linked by thin filaments. These images indicate similar 3-D distributions for rDNA probes and Ag-NOR proteins. The beaded organization of the transcriptional regions in the nucleoli is discussed.

Mechanical performance of spared myocytes after myocardial infarction in rats: effects of captopril treatment.

To determine the effects of myocardial infarction-induced left ventricular failure on the mechanical characteristics of the remaining viable myocytes, coronary arterial occlusion was performed in rats, and cell function was examined 1 wk later. Moreover, to establish the mechanisms by which treatment with angiotensin-converting enzyme inhibitors ameliorates cardiac dynamics, captopril was administered immediately after surgery, and the contractile behavior of the unaffected cells was similarly analyzed 7 days later. The severe impairment in left-side pump function was found to be associated with a decrease in the velocities of myocyte shortening and relengthening and peak shortening despite a prolongation of contraction duration. In addition, a uniform property was recognized in myocytes from infarcted and noninfarcted hearts. Longer cells manifested greater velocity of shortening, whereas wider cells of identical length exhibited depressed shortening velocity. After infarction, the depression in cell contractility coupled with lateral expansion of myocytes exceeded the influence on cell mechanical behavior linked to myocyte lengthening leading to an overall decrease in contractility of the hypertrophied cells. Captopril therapy preserved, in part, the ability of myocytes to shorten and relengthen, which was accompanied by a decrease in the lateral and longitudinal expansions of these cells.

Arrhenius modeling to predict geosynthetic degradation

A methodology for the determination of the degradation of polymeric materials used in long-term applications such as landfill liners and covers, vertical and lateral expansions of solid waste facilities, retaining wall and slope reinforcement, etc., is the focus of this paper. Attention is placed on geomembrane barriers, but geotextile filters, geonet and geocomposite drains, geogrid and geotextile reinforcement and plastic pipe might also be involved. The predictive technique most widely used for polymer degradation (and explained throughout this paper) is based on a time-temperature superposition principle, and is called ‘Arrhenius modeling’ in this paper. It uses high-temperature incubation of the polymeric material in question followed by some type of laboratory testing, in order to extrapolate the experimental behavior to the site-specific, and lower, temperature. The tacit assumption involved is that the material's behavior within the high-temperature incubation range (as indicated by the activation energy, ‘E act’) is constant within this range and can be extrapolated to the lower temperature behavior of practical interest. Assuming this to be the case (it is obviously a critical assumption and promises to be difficult with oriented geosynthetic products), the nature of the experiments used to identify the amount of degradation becomes very significant. We have outlined 13 candidate tests (there are undoubtedly more) for the evaluation of polymers commonly used to manufacture geosynthetics. They are grouped in the mechanical, physical and chemical test method categories. Each test method is described in some detail. Furthermore, an attempt has been made to predict how the various responses might behave in their elevated temperature test environments. Using these trends, an Arrhenius plot can be generated, and a prediction of degradation to a site-specific temperature should be possible to obtain. It is hoped that this paper will stimulate discussion (and even controversy) and, if warranted, an intensive research effort in this area. With a strong enough effort, a single geosynthetic material can be investigated by a number of different testing techniques to see if a consensus regarding degradation times is reached. At the minimum, such a broad-based approach should identify which testing method is preferred for use in Arrhenius modeling. At this point, that particular method(s) can be used on all of the different polymer materials used in a particular application to see which one possesses the best resistance to a specific type of degradation.

Observations on the life-cycles of two haploporid trematodes, Carassotrema bengalense Rekharani & Madhavi, 1985 and Saccocoelioides martini Madhavi, 1979

The life-cycles of two species of haploporid trematodes, Carassotrema bengalense Rekharani & Madhavi, 1985 and Saccocoelioides martini Madhavi, 1979, are illustrated. The molluscan host of the two species is the prosobranch gastropod Stenothyra blanfordiana (Nevill), which occurs in abundance in Chilka Lake, a large brackish-water lagoon. The cercariae are gymnocephalous, bi-ocellate and distomate. The cercaria of C. bengalense is characterised by the presence of thin lateral expansions of the tail, long tubular caeca, dense cystogenous glands and a Y-shaped excretory bladder. The cercaria of S. martini, on the other hand, has a simple tail, a prominent pharynx, short elliptical caeca lined by tall cells and an I-shaped excretory bladder. Both of the cercariae encyst on algae. Adults of C. bengalense occur in Mugil cephalus L. and Valamugil cunnesius (Val.), while those of S. martini occur in M. cephalus, Liza macrolepis (Smith), Etroplus suratensis (Bloch) and Hilsa ilisha (Hamilton).

Structure of the urinary bladder in the Pacific cod

The urinary bladder of the Pacific cod,Gadus macrocephalus was investigated. A pair of ureters was found to unite and form a sac-like protrusion on the posteroventral aspect of the gonad. This protrusion was confirmed as the urinary bladder based on its histology and the presence of ammonia and urea in the fluid within this structure. The urinary bladder consisted of a central lumen and two lateral expansions found on the right and left sections. The luminal epithelial cells of the Pacific cod urinary bladder, unlike those of other animals, were characterized by microvilli on the free surface, and the presence of a number of vesicles and mitochondria across the apical portion on the cells. This suggests that the luminal epithelium of the urinary bladder might be actively engaged in transportation of water or other materials from the urine. The Pacific cod urinary bladder may therefore be closely associated with osmoregulation by reabsorbing water from the urine. Ammonia-N and urea-N levels of 65–213 μg/dl and 1.5–3.5 mg/dl were measured in the fluid which filled the urinary bladder.

Thermal buckling of curved railroad tracks

Previous buckling analyses of curved railroad tracks did not take into account the prebuckling lateral expansion of the rails and/or have made the simplifying assumption that the lateral resistance which the ballast exerts on the rail-tie structure is either constant or linear. In this paper, a more refined analysis is presented, which accounts for the prebuckling lateral expansions, and which uses a bilinear response for the lateral resistance, and a non-linear response for the axial resistance. The governing equations are derived from a variational formulation. The obtained solution is exact. It was found that for curves with decreasing radius the safe temperature change, T L , decreases. The results are compared with full scale field test results. The comparison indicates that the analytically obtained safe temperature increases, T L, are on the safe side and thus can be used for design and maintenance purposes. To simplify the use of the obtained solution, it was evaluated numerically for a range of track parameters and the results are presented as graphs.