bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of actin and tropomyosin in hearts of cardiac mutant axolotls by two‐dimensional gel electrophoresis, western blots, and immunofluorescent microscopy
Authors: Starr Christopher M. , Diaz Jose G. , Lemanski Larry F. 
Published: February 2005

AbstractWhen homozygous, recessive mutant gene c in Ambystoma mexicanum results in a failure of embryonic heart function. This failure is apparently due to abnormal inductive influences from the anterior endoderm resulting in an absence of normal sarcomeric myofibril formation. Biochemical and immunofluorescent studies were undertaken to evaluate the contractile proteins actin and tropomyosin in normal and mutant hearts. For the immunofluorescent studies, cardiac tissues were fixed in periodate‐lysine‐paraformaldehyde, frozen sectioned, and immunostained by an indirect method with monospecific polyclonal antibodies produced against highly purified chicken heart actin and tropomyosin. In normal hearts, both antiactin and antitropomyosin stained the myofibrillar I‐bands intensely. In mutant hearts, intensity of staining with antiactin antibody was similar to normal, although sarcomeric patterns were not observed. Staining intensity for tropomyosin with antitropomyosin antibody was significantly reduced in mutant hearts when compared to normal. Biochemical studies were used to evaluate antibody specificity, antigenic variability, and relative protein concentrations of actin and tropomyosin in normal and mutant cardiac tissues. Tissue homogenates were electrophoresed in two dimensions, and second‐dimension slab gels were either Coomassie Blue silver‐stained or transblotted onto nitrocellulose and the proteins stained with antibodies. Stained gels and immunoblots of cardiac proteins reveal that the amounts of actin isoforms are identical in normal and mutant hearts. However, these methods demonstrate a significantly reduced amount of tropomyosin in mutant tissue. This confirms earlier studies suggesting reduced amounts of tropomyosin in mutant hearts based upon immunological assays. Thus, failure of normal myofibrillogenesis in gene c mutant hearts does not appear to result from a change in actin isoform composition but may be related to a deficiency in tropomyosin.
Lungs of Polypterus and Erpetoichthys
Authors: Lechleuthner A. , Schumacher U. , Negele R. D. , Welsch U. 
Published: February 2005

AbstractThe wall of the asymmetrical saclike lungs of the fishes Polypterus and Erpetoichthys consists of several functionally different tissue layers. Their lumen is lined by a surface epithelium composed of (1) highly attenuated cells, termed pneumocytes I; (2) pneumocytes II with lamellar bodies, presumably indicating surfactant production; (3) mucous cells; and (4) ciliated cells. Underlying the pneumocytes I is a dense capillary net. The thin continuous endothelium of this net, together with the pneumocytes I, constitute the very thin blood‐air barrier. The basement membrane of epithelium and endothelium fuse in the area of the blood‐air barrier (thickness 210 m̈m). Secretory and ciliary cells form longitudinal rows in the epithelium. Below the zone with a gas‐exchanging tissue, a layer of connective tissue containing collagen and special elastic fibers occurs. The blood vessels that give rise to or drain the superficial capillary plexus are located in this connective tissue. The outermost layer of the lung consists of muscle cells, a narrow inner zone with smooth muscle cells, and an outer, broader zone with cross‐striated muscle cells. The lung is innervated by myelinated and nonmyelinated nerve fibers. The morphology of the gas‐exchange tissue in the lungs of these primitive bony fish is fundamentally very similar to that of the lungs of tetrapod vertebrates. The morphologic observations are in close agreement with physiologic data, disclosing well‐developed respiratory capacities. Structural simplicity can be regarded as a model from which the lungs of the higher vertebrates derived. In addition to respiratory function, the lungs seem also to have hydrostatic tasks.
Immunofluorescent, immunogold, and electrophoretic studies for desmin in embryonic hearts of normal and cardiac mutant mexican axolotls, Ambystoma mexicanum
Authors: Shen Pei‐Shen , Lemanski Larry F. 
Published: February 2005

AbstractRecessive mutant gene c for “cardiac nonfunction” in axolotls results in an absence of normal heart contractions in affected embryos due to a failure of myofibril formation. In the present study, the intermediate filament protein, desmin, is compared in developing normal and mutant hearts by means of two‐dimensional gel electrophoresis, immunofluorescent microscopy, and immunoelectron microscopy. Tissues were fixed in periodate‐lysine‐paraformaldehyde or paraformaldehyde‐glutaraldehyde solutions and rapidly frozen or embedded in Lowicryl resin. Frozen sections stained with FITC‐conjugated antibodies by an indirect approach revealed that desmin is localized in the I‐band regions of adult cardiac myofibrils. In normal embryonic hearts at stage 32 (preheartbeat) desmin is localized as “spots” or amorphous collections in the cells. As development progresses to stage 35, staining for desmin in normal hearts becomes more intense with localization being most pronounced at the cell peripheries. By stage 41 most of the desmin in normal hearts is localized in the I band areas of the organized myofibrils and the staining of amorphous areas is much less prominent. During early development, the distribution of desmin in mutant hearts is similar to normal. However, while most of the desmin in normal organs at stage 41 is associated with myofibrils, the staining remains diffuse in mutants. Twodimensional gel electrophoresis reveals comparable patterns for desmin from normal and mutant hearts. Immunogold staining shows desmin localization to be between the myofibrils and around the I‐band regions in adult cardiac muscle and in stage 41 normal embryonic hearts. Immunogold staining confirms a diffuse distribution of desmin in mutant hearts.
Ontogeny of gut morphology in the white shrimp Penaeus setiferus (Decapoda, Penaeidae)
Authors: Lovett Donald L. , Felder Darryl L. 
Published: February 2005

AbstractOntogeny of the gut in Penaeus setiferus was investigated by reconstruction of serial sections examined by light microscopy. Development of the gut into the adult form is protracted over several weeks beyond metamorphosis in steps that may be directly related to the unique postlarval life history of Penaeus. The gastric mill is lacking in larval stages of P. setiferus. In protozoeal stages Z1‐Z3, the pyloric ampullae are blind sacs that do not communicate with the midgut. The gland filter first appears in mysis stage M2. The gastric mill in early postlarval (PL) stages consists of poorly chitinized lobes with flexible setae. By PL21 the ossicles of the gastric mill are rigid and setae are replaced by spine‐like denticles, but even by PL35 the gastric mill is neither as massive nor heavily chitinized as in adults. During the mysis stages and early PL stages, the hepatopancreas communicates freely with both the foregut and the midgut trunk. By PL35 the hepatopancreatic ducts are essentially isolated from the remainder of the midgut by foregut ossicles.The midgut in Z1 consists of two pairs of simple caeca and the midgut trunk. During larval growth, each of the lateral midgut caeca develops into a number of lobes. After metamorphosis these lobes begin to ramify into small‐diameter tubules, and by PL35 have completely ramified into the hepatopancreas of adults. From M1 to PL4, the anterior midgut caeca decrease in absolute size and become a single anterior diverticulum. The posterior midgut diverticulum first appears in PL21 as a simple sac and thereafter increases in size and complexity.
Connecting bridges between axoneme and other components in the sperm tail of some insects
Authors: Afzelius Björn A. , Dallai R. 
Published: February 2005

AbstractSpermatozoa from three insect groups were examined by electron microscopy and found to have bridges that connect some of the axonemal doublets with either the two mitochondrial derivatives or, in the phasmids, the so‐called laminated bodies. Within Hemiptera Heteroptera the bridges extend from doublet Nos. 1 and 5, within chrysopid neuropterans from doublet Nos. 2 and 5, and in the phasmids from axonemal doublet Nos. 2 and 4. Bridges were looked for in spermatozoa from several other insect groups but not found. The bridges in the chrysopids are regularly curved rather than straight. While bridges in heteropterans and chrysopids were seen in spermatozoa fixed with “standard fixatives,” those in the phasmids were distinctly resolved only in spermatozoa that had been fixed with a tannic acidcontaining fixative. In spite of these differences, it is conceivable that the bridges in these three insect taxa are all derived from similar, faint, bridge‐like connections that sometimes can be seen to extend from all or many doublets toward the axonemal sheath of the early insect spermatid. These bridges or bridge‐like structures might have a morphogenic function in that they may specify the location of the mitochondria later to become mitochondrial derivatives or, in the phasmids, of the laminated bodies.
Ultrastructure of the adenohypophysis in the anadromous sea lamprey, Petromyzon marinus, during metamorphosis
Authors: Wright Glenda M. 
Published: February 2005

AbstractThe ultrastructural changes occurring in the adenohypophysis (AH) of the anadromous sea lamprey, Petromyzon marinus, during metamorphosis (stages one through seven) were examined. The rostral pars distalis initially contains one granulated (secretory) cell type A and one nongranulated type I cell. A second granulated cell (type B) appears during the later stages (stages six and seven) of metamorphosis. The most pronounced ultrastructural changes take place in the caudal pars distalis (CPD). Initially, most cells (80–90%) are nongranulated cells type II and some type I. Granulated type C and D cells form the remainder of the CPD. Almost all cells during stages three and four demonstrate a marked increase in synthetic activity evident by conspicuous Golgi regions, abundant rough endoplasmic reticulum (RER), and increased cell volume. Most cells are sparsely granulated. Secretory cell types C and D and, two new cell types, E and F, are present. Synthetic activity subsides by stage five. Most cells (80–90%) during stages five through seven are granulated. Type E are most prevalent with variable numbers of types C and D and few type F. Nongranulated cells now represent only 10–20% of the CPD. The increase in granulated cells occurs at the expense of type II cells that differentiate into granulated cell types. The fine structure of the pars intermedia throughout metamorphosis remains similar to that of the larva. Most cells are granulated, highly vesiculated type G cells. A few nongranulated type I cells are also present. The functional significance of the secretory cells in the AH is related to the requirement for an intact pituitary gland for the initiation and completion of metamorphosis.
Segregation of primordial germ cells: Their numbers and fate during early development of Barbus conchonius (Cyprinidae, Teleostei) as indicated by 3H‐thymidine incorporation
Authors: Timmermans L. P. M. , Taverne N. 
Published: February 2005

Abstract3H‐Thymidine incorporation experiments in Barbus conchonius showed that presumptive primordial germ cells (PGCs) terminated their mitotic activity between midepibolys, and late epiboly. At the ten‐somite stage, shortly after labeling of PGCs by uptake of 3H‐thymidine became arrested, they could be recognized by their relatively large size and large nucleus. They were located in two longitudinal rows of cells between mesoderm and periblast, always at the same distance to the left and right of the notochord. Contact with the endoderm was not observed before the 16‐ to 23‐somite stage. The numbers of PGCs were small (mean number, 18–19) and remained small for nearly 3 weeks. Mitotic activity was not observed in PGCs during that period; thereafter, rapid proliferation began. There is no evidence for active migration of PGCs; it is assumed that they are merely translocated passively together with their surrounding tissues. No specific constituents were detected with histochemical methods for glycogen, alkaline phosphatase, and RNA. Electron microscopy revealed the presence of “nuage” around the nucleus of PGCs. This material corresponded with perinuclear dense bodies as seen with light microscopy from the 19‐somite stage onward.It is concluded that presumptive PGCs segregate from the somatic cells between midepiboly and late epiboly, before the three germ layers have been formed, and that locations of PGCs in the endodermal or mesodermal layer may be merely transitory stages during their translocation toward the gonadal primordia.
Cellular structure and ultrastructure of the black coral Antipathes aperta: 1. Organization of the tentacular epidermis and nervous system
Authors: Goldberg Walter M. , Taylor George T. 
Published: February 2005

AbstractThe tentacular epidermis of the black coral Antipathes aperta is organized into three distinct regions, containing at least nine different types of cells. The outermost region is dominated by spirocytes along with two types of nematocytes, organized into discrete wart‐like batteries. The two nematocyte types both contain microbasic b‐mastigophore nematocysts. The outer boundary of the wart is marked by the presence of both spumous and vesicular mucus cells. The ciliation of the wart is contributed principally by the spirocytes. Warts are enveloped and separated from one another by an unusual neurosensory cell complex that extends from the tentacular surface to the mesogleal connective tissue foundation. Funnel‐like, flagellated cells composing the complex connect with ganglion cells composing the dominant portion of the nerve net system. Branches of this complex also penetrate the central portion of the wart, making direct contact with the cnidae. The tentacular mid‐region is composed of nematocytes and spirocytes in various stages of maturation, along with epitheliomuscular cell (EMC) somata. The EMC's narrow apically extend toward the tentacle surface, forming contacts with the cnidae. The basal end of the EMC expands to form the larger portion of the tentacular musculature. The inner region of tentacular epidermis is marked by a neuromuscular complex sheathed by extensions of mesoglea. The ganglion cells occur as a plexus deep within the tentacle and form polarized junctions with the EMC's, but neuromuscular synapses are not well enough defined for documentation. Polarized synapses lacking well‐defined membrane thickenings characterize the interneuronal junctions. Granular cells lining the mesogleal surface appear to be responsible for mesogleal fibrillogenesis.
Cellular structure and ultrastructure of the black coral Antipathes aperta: 2. The gastrodermis and its collar cells
Authors: Goldberg Walter M. , Taylor George T. 
Published: February 2005

AbstractThe gastrodermis of the black coral Antipathes aperta is associated with eight distinct types of cells, including two types of microbasic b‐mastigophores (nematocysts), spumous and vesicular mucus cells, and ganglion cells that are essentially the same as in the epidermis. Three additional types of cells are unique to the gastrodermis, and are readily distinguished from those of the epidermis by their electron‐opaque inclusions. These include lipoidal cells, zymogen digestive cells, and an unusual type of epitheliomuscular collar cell. The pharyngeal region is characterized by the presence of electron‐opaque nematocysts, a scattering of zymogen cells, and a large number of collar cells. The latter are distinguished in part by the presence of dense microfibrillar processes that surround the microvilli and extend into adjacent collars. This interconnection results in the formation of an extensive pharyngeal meshwork. These collar cells are additionally distinguished by the placement of the collar and flagellum adjacent to a flared cup of cytoplasm. This portion of the cell is capable of endocytosis of relatively large unicellular prey, and apparently is capable of forming digestive vesicles as well. The pharyngeal gastrodermis grades into simple lobate septal filaments toward the base of the coelenteron, where large, granular nematocysts all but replace the smaller electron‐opaque types Collar cells are found here as well, but in fewer numbers compared to the zymogen cells. Ultrastructural results are compared with those of other coelenterates and discussed in terms of food and modes of nutrition.
Structure, function, and evolutionary significance of the reproductive system in males ofHebrus ruficepsandH. pusillus(heteroptera, gerromorpha, hebridae)
Authors: Heming‐van Battum Karin E. , Heming B. S. 
Published: February 2005

AbstractIn Holland, bugs of the speciesHebrus pusillusandH. ruficepshave one generation per year and overwinter as unmated adults. Males have two testes with two follicles + vasa efferentia each, paired vasa deferentia and seminal vesicles, an ejaculatory duct, and a protrusible phallus comprising an articulatory apparatus, phallotheca, endosoma, and paired claspers. The skeletomusculature of this system is described (it has 12 paired and four unpaired muscles) and its functions in generating and transferring sperm (summarized in Figs. 70–75) are reconstructed from study of living bugs, dissections, whole mounts, and serial sections.Males of both species produce sperm >2 mm long from stem spermatogonia in the germarium of each follicle. Initial definitive spermatogonia divide synchronously three times to form clones of eight, interconnected, primary spermatocytes. These enlarge up to 43‐fold in males ofH. pusillusand 78‐fold in those ofH. ruficeps, undergo meiosis, and, after adult emergence, complete their differentiation into bundles of 32 sperm which coil transversely about the periphery of each follicle at its base. These begin to enter the vasa efferentia in mid August, rupture, and release their sperm into the seminal vesicles where they are stored overwinter. Most spermatocyte and spermatid cysts remaining in the testes degenerate in fall, leaving only stem spermatogonia and a few early spermatocysts in the germaria.Males ofH. pusillusbegin to mate the first warm days of spring but only the most persistent succeed. A male jumps on the back of a female, induces her to lower her ovipositor, and, within 12 min (@ 18–24°C), introduces the endosoma of his phallus up its shaft and fills his seminal duct with sperm. The female draws this into her gynatrial sac at the end of copulation and transfers it into her spermatheca in about 30 min, the sperm reversing themselves within it so that their heads face towards its mouth. The male may stay on her back for up to 2 hours and may copulate again up to three times before leaving to mate with other females.Males ofH. pusillusmay be sexually active for months after overwintering, because spermatogonia in their germaria reactivate in spring to produce additional sperm. Those ofH. ruficepsdo not and males mate successfully only until their supply of overwintered sperm is exhausted.The chromosome complement ofH. pusillusmales is 2N = 22 + XY. The X and Y chromosomes are of unequal length, form a pseudo pair at metaphase I, and segregate to opposite poles at anaphase I—the first instance of pre‐reductional segregation of sex chromosomes to be recorded in the Gerromorpha. The chromosome complement ofH. ruficepsmay be 2N = 24 + XO but the nature of two chromosomes was not resolved. The single X segregates to half the spermatids at anaphase II.
Ultrastructure of neuroendocrine cells in the lungs of three anuran species
Authors: Goniakowska‐Witalińska L. , Cutz E. 
Published: February 2005

AbstractNeuroendocrine cells in the lungs of three species of anurans, Bombina variegata, Bufo bufo and Bu. viridis, occur both as single cells and in the form of neuroepithelial bodies. Neuroendocrine cells are covered by ciliated cells or pneumocytes, which separate them from the lumen of the lung. Neuroepithelial bodies are dispersed in the apical part of the main septa of lungs of Bo. variegata and Bu. bufo or are situated on special protrusions of septa in the lungs of Bu. viridis. Neuroepithelial bodies are innervated by intraepithelial nerve endings of afferent and efferent types.
Comparative buccal anatomy in Helisoma (mollusca, pulmonata, basommatophora)
Authors: Smith David A. 
Published: February 2005

AbstractDissections were performed to document buccal anatomy in three species of the pulmonate genus Helisoma Swainson, 1840. The 28 muscles which are responsible for radular feeding in these animals are organized in three concentric and integrated envelopes. The deepest of these includes muscles which manipulate the radula about the odontophoral cartilage. Elements of the middle envelope direct movements of the cartilage within the buccal cavity, and muscles of the outer envelope control movements of the buccal mass within the cephalic haemocoel. Motion analysis by videomicrography showed that muscles of the middle and outer envelopes contribute to the action of radular feeding by acting as antagonists to other muscles and to hydrostatic elements of the buccal apparatus. Observations of radular dentition showed that although each of the three species examined has a unique radula, especially with regard to the specific details of tooth shape, all resemble a radula characteristic of the Planorbidae with regard to other, more general, aspects of ribbon architecture.
Torsion in the asteroid ray
Authors: O'neill Patricia L. 
Published: February 2005

AbstractAlthough torsion (axial twisting) is rare in living structures, some starfish routinely use ray torsion in the righting process. This study examined the torsional properties of the ray and dorsal body wall of Echinaster spinulosus (Echinodermata: Asteroida: Spinulosidae). The body wall of the ray is composed of a reticular skeleton composed of CaCO3 ossicles sandwiched between collagenous layers in which the fibers are orthogonally oriented. G, the shear modulus of the dorsal body wall, determined from a torsion pendulum, was 95.3 MPa, and damping was extremely pronounced (Δ = 1.36). The torque‐rotation curve was J‐shaped, and G determined from this data was 176 MPa. Torsional stress relaxation was rapid, with the relaxation spectrum skewed to the left and τmax = 2.3 for anaesthetized tissue and 2.7 for unanaesthetized tissue.Analysis of ray geometry showed that the ambulacral groove reduced torsional stiffness by about two orders of magnitude compared to an ungrooved ray. Ray taper reduced the stiffness of the tip relative to the root. The shear stress distribution determined for the ray cross‐section showed stress concentrations around the ambulacral arch, the outer body wall surface, and the inner body wall surface. The ossicles are situated to minimize torsional stiffness of the ray.