Ultrastructure of the aortic diverticula of the adult dragonfly Sympetrum danae (Odonata: anisoptera)

Summary The aorta of Sympetrum danae possesses two dorsal diverticula: one in the mesothorax and one in the metathorax. They are very similar in form and position. Each diverticulum has a dorsal valve through which blood is pumped from the wings down into the aorta. The wall of the aortic diverticula consists of two simple cell layers: an outer epidermis-like layer and an inner muscle layer. The nuclei of the muscle cells are situated close to the lumen of the diverticula. The mitochondria are evenly dispersed between the myofibrils and are often paired up on either side of the Z-band. The Z-bands are thick and fragmented. The length of the sarcomeres varies from 3.3 to 6.1 . The A-band length is about 3 . The myofibrils consist of thick (250 Å) and thin (85 Å) filaments. Each thick filament is surrounded by 9–12 thin filaments. The sarcoplasmic reticulum is well developed and separates the myofibrils with one or two layers. The T-tubules are flattened and branch irregularly like a two-dimensional tree between the lamellar myofibrils. Intercalated discs are observed.The peculiarities of the muscle of aortic diverticula in S. danae are discussed in relation to various muscles of other insects and arthropods.     

The probability of interspecific competitive situations in scale-insects (Homoptera,Coccoidae)

Summary A large scale survey, covering some 25 million km² of Eastern-Europe, provided distributional data, and a more detailed picture on factors determining species composition and abundance of scale-insects colonizing deciduous orchard trees. No interspecific competition or competitive situations were detected among the 21 scale insect species, when taking into consideration the whole geographic area surveyed. Of all cases, 3.2% showed significant spatial separation in smaller geographic regions. However, no evidence for competition was found between species with overlapping distributions. In the case of introduced species, the role of past competition can also be excluded. Separation was thought to be determined by differences in ecological requirements. There is some probability of competition in the transitional zone (significant separation in 0.8% of cases), and somewhat more (2.4%) in the Southern zone. There was potential competition between species classified as Mediterranean and invader subguilds (7.1% of frequent species pairs), as well as between the Southern and invader (2.4% of frequent species pairs) subguilds. Its probability was very low between the species of the endemic (0.8% of frequent species pairs) and invader (1.6% of frequent species pairs) subguilds.     

Current chemical concepts of acids and bases and their application to anionic (“acid”) and cationic (“basic”) dyes

Summary In biomedical studies, dyes are divided into acid and basic dyes. This classification cannot be reconciled with current chemical definitions of acids and bases. Brönsted-Lowry acids are compounds that can donate protons; bases are proton acceptors. The definition of acids and bases is independent of the electric charge, i.e. acids and bases can be neutral, anionic or cationic. Reactions between acids and bases result in formation of new acid-base pairs. Lewis acids and bases do not depend on a particular element, but are characterized by their electronic configurations. Lewis bases are electron donors; Lewis acids are electron acceptors. This classification is also unrelated to the electric charge. Lewis acids and bases interact by formation of coordinate covalent bonds.In histochemistry and histology, dyes containing SO ₃ ^– , –COO^– and/or –O^– groups are classified as acid dyes. However, such compounds are electron pair donors and hence Brönsted-Lowry and Lewis anionic bases. Dyes carrying a positive charge are termed basic dyes. Chemically, many cationic dyes are Lewis acids because they can add a base, e.g. OH^–, acetate, halides. The hypothesis that transformation of –NH₂ into ammonium groups imparts basic properties to dyes is untenable; ammonium groups are proton donors and hence acids. Furthermore, conversion of an amino into an ammonium group blocks a lone electron pair and the color of the dye changes drastically, e.g. from violet to green and yellow. It appears therefore highly unlikely that ammonium groups are responsible for binding of cationic (basic) dyes. In histochemistry, it is usually not of critical importance whether anionic or cationic dyes are chemically acids or bases. It is therefore suggested to substitute the terms anionic for acid and cationic for basic dyes; this nomenclature will always be chemically correct.     

Location of heitz's zerstäubungsstadium (dispersion phase) in the mitotic cycle ofPhaseolus coccineus and the concept of Angiosperm endomitosis

Summary DNA microdensitometry and autoradiography after treatment with³H-thymidine were used to study the phase of dispersion of chromocenters (Z phase) in parallel with chromocentric nuclei inPhaseolus coccineus. In all materials studied, two types of chromocentric nuclei were present.In radicle apices of dry seeds, two classes of nuclear DNA contents were measured, 2 C (G₁) and 4 C (G₂). The 2 C DNA class comprised all chromocentric type I nuclei, the 4 C class included Z phases and chromocentric type II nuclei. The 4 C (G₂) condition of Z phases implies that Z phases maintain their nuclear structure for some time after the end of DNA replication. Shoot apices also contain 2 C (G₁) and 4 C (G₂) nuclei but 4 C nuclei (Z phases and chromocentric type II nuclei) are rare.In seedling root apices, Z phases are from 1.02 to 4.08 times as frequent as prophases. This excludes that Z phase is a very early prophase. DNA microdensitometry shows that the chromocentric type I includes 2 C (G₁) nuclei and nuclei in the first part of the S phase, Z phases include 4 C (G₂) nuclei and nuclei in the last stage of the S phase and chromocentric type II includes mainly 4 C (G₂) nuclei and nuclei in the second part of S. After 90 minutes of treatment with³H-thymidine all Z phase nuclei are labeled. This result and the microdensitometric data unequivocally demonstrate that Z phase is located at the end of S.The present results and those of previous authors on Z phase are discussed in relation to Geitler's concept of Angiosperm endomitosis. It is concluded that the term Angiosperm endomitosis must be abandoned and substituted by the term chromosome endoreduplication.     

α-Gustducin immunoreactivity in the airways

The G-protein subunit -gustducin is a marker of chemoreceptive cells. In the present study, we examined the immunohistochemical localization of -gustducin in rat airway epithelium both by light and electron microscopy. -Gustducin immunoreactivity was found in solitary cells that presented ultrastructural features of chemoreceptor cells, i.e. flask-shaped or pear-shaped, with an apical process with thin microvilli protruding into the lumen. The immunostaining was mainly concentrated in the apical process and along the basolateral cell surface. To investigate whether -gustducin-immunoreactive cells represented a distinct cell subset in rat airways, we performed double-label immunocytochemistry with antibodies to protein gene groduct (PGP) 9.5, a marker of neuroendocrine cells, and to phospholipase C beta2 (PLC2), a component of the bitter signalling pathway. -Gustducin-immunoreactive cells were present in a subset of PGP-9.5-immunoreactive elements, although not all -gustducin-positive cells expressed PGP 9.5 labelling. In addition, a subset of -gustducin-expressing cells colocalized PLC2. This work thus demonstrates that solitary -gustducin-immunoreactive cells exist throughout the airways and represent a specialized cell type with morphological and immunohistochemical characteristics of chemoreceptor cells.     

The contractile apparatus of striated muscle in the course of atrophy and regeneration

Summary The ultrastructure of the contractile apparatus of the rat soleus muscle during the course of denervation atrophy was investigated. It was found that the ratio of thin to thick filaments increased in myofibrils of atrophying muscle fibers. Elevation of the ratio was observed as early as the second day after denervation, and became more pronounced with the progress of atrophy. Parallel measurements of the amounts of actin and myosin in the myofibrils and in the muscle protein extracts revealed a lower proportion of myosin heavy chains to actin in the fractions from denervated muscles, compared with the control values. Both the electron-microscopic observations and the biochemical evaluation of the actin content of the muscle, suggests that the elevated ratio of thin to thick filaments seen in the course of the muscle atrophy appears as the result of an earlier and more intensive disappearance of thick filaments. Thin filaments disappeared more slowly, in parallel to the decrease in muscle weight.On the basis of the results presented a mechanism of progress of simple atrophy of muscle in suggested.     

Morphological development and gibberellin production by different strains of Gibberella fujikuroi in shake flasks and bioreactor

Strain H-984 of G. fujikuroi grown for 38h in a shake flask with medium containing 20g glucose l^–1, 3g yeast extract l^–1, 2.5g NH4NO3 l^–1, 0.5g KH2PO4 l^–1, 0.1g MgSO4 l^–1, 1g CaCO₃ l^–1, and inoculated into a bioreactor with medium containing 60g glucose l^–1; 1g NH_4Cl l^–1; 3g KH2PO4 l^–1 and 1.5g MgSO₄ l^–1 produced 1100mg gibberellic acid l–1.     

Immunofluorescence staining of thin-filament sections not participating in actomyosin crossbridges: Studies by use of a monoclonal antibody specific to actin

Summary Monoclonal antibodies (mcab) were produced in vitro by fusing mouse X63-Ag8.653 plasmacytoma cells with spleen cells from a Balb/c mouse immunized with primary cultures of chick skeletal muscle (pmcc). After cloning on agar, stable clones were obtained, the antibodies of which stain specifically the I-band of myofibrils in the immunofluorescence (IF) procedure. For further characterization of these mcab their affinities to muscle proteins were tested by immunoblotting and by enzyme-linked immunosorbent assay (ELISA). Mcab specific for actin were revealed by these criteria. One of the anti-actin antibodies, mcab 647, reveals a variety of IF-staining patterns on myofibrils. On rest-length myofibrils the I-band is labeled only. However, at sarcomere lengths below 2 m, where the thin filaments meet in the middle of the A-band and form a region of double overlap, an additional fluorescent band appears in this position. The fluorescence intensity of this band is increased significantly in shorter sarcomeres. Finally, when the I-band has disappeared at a sarcomere length of 1.5 m, fluorescence is located exclusively in the middle of the A-band. These IF-staining patterns suggest that only those sections of the thin filament are stained that do not participate in actomyosin crossbridges.     

Electron microscopy of the impulse conducting system op the sheep heart

Summary Electron micrographs of the conducting system of the sheep heart show it to be strictly cellular in nature. All protoplasmic components are restricted to areas defined by the individual plasma membranes of the cells. The individual cells are surrounded by a common interspace and groups of cells are separated from neighboring connective tissue by a common, longitudinal basement membrane. The extracytoplasmic interspace shows occasional enlargements, probably corresponding to the intracytoplasmic vacuoles visualized in the light microscope. The apposing plasma membranes, along which ephaptic thickenings may occur, and their interspace form the intercalated discs of the system.Myofibrils are few and are situated preferentially immediately beneath the plasma membrane. Chains of myofibrils, interrupted at the intercalated discs, appear to course through the whole tissue. In some myofibrils the pattern of long periods may be interrupted by a small-period pattern for several sarcomeres.The cytoplasmic matrix consists mainly of fine filaments of unknown composition. The relatively scarce mitochondria are found near the nucleus, myofibrils and cell surface. The endoplasmic reticulum is poorly developed and its arrangement is a comparatively loose one.The above results and their physiologic consequences are discussed, particularly with regard to the core conduction theory in conducting tissue.This study was aided, in part, by grant number H-3493, from the National Heart Institute of the National Institutes of Health, Department of Health, Education and Welfare, Bethesda, Maryland.     

Nuclear characteristics of cardiac myocytes following the proliferative response to mincing of the myocardium in the adult newt,Notophthalmus viridescens

Summary Amphibian cardiac myocytes are predominantly mononucleated and have been demonstrated to respond to injury with DNA synthesis and mitosis. The nature of this response with regard to nuclear number and ploidy is unclear. In this study, the apex of the newt ventricle was minced and replaced, increasing the reactive area of the wound. At 45 days after mincing following multiple injections of tritiated thymidine (2.5-Ci/animal, 20 Ci/mM) 15 to 20 days after mincing, three ventricular zones were isolated and fixed: Zone 1, the minced area; Zone 2, extending approximately 500 m proximally from the amputation plane; and Zone 3, the portion proximal to Zone 2. Myocytes separated in 50% KOH were examined for DNA synthesis by autoradiography and for nuclear number and DNA content using a scanning microdensitometer on Feulgen-Naphthol yellow S-stained cells. No labeled myocyte nuclei were found in control hearts and 98.3% of the myocytes were 2C. At 45 days, 46.78% of myocyte nuclei within Zone 1 were labeled, while 13% were non-diploid. In Zone 2, 9.25% were labeled with 4.8% non-diploid. In Zone 3, 1.1% were labeled, with 2.8% non-diploid. The newt ventricle's response to injury apparently may involve complete mitosis and cytokinesis, resulting in mononucleated diploid cells.     

Interaction of force transmission and sarcomere assembly at the muscle-tendon junctions of carp (Cyprinus carpio): ultrastructure and distribution of titin (connectin) and α-actinin

At muscle-tendon junctions of red and of white axial muscle fibres of carp, new sarcomeres are found adjacent to existing sarcomeres along the bundles of actin filaments that connect the myofibrils with the junctional sarcolemma. As the filament bundles that transmit force to the junction originate proximal to new sarcomeres, they probably relieve these new sarcomeres from premature loading. In red fibres, these filament bundles are long (up to 20 m) and dense, permitting light-microscopical immunohistochemistry (double reactions: anti-titin or anti--actinin and phalloidin). New sarcomeres have clear I bands; their A band lengths are similar to those of older sarcomeres and the thick filaments lie in register. T tubules are found at the distal side of new sarcomeres but terminal Z lines are absent. The late addition of -actinin suggests that -actinin mainly has a stabilizing role in sarcomere formation. The presence of titin in the terminal fibre protrusions is in agreement with its supposed role in sarcomere formation, viz. the integration of thin and thick filaments. The absence of a terminal Z line from sarcomeres with well-registered A bands suggests that this structure is not essential for the anchorage of connective (titin) filaments.     

Differentiation of histospecific ultrastructural features in cells of cleavage-arrested early ascidian embryos

Summary Ultrastructural features of histospecific differentiation were found in early cleavage stage ascidian embryos treated with cytochalasin B and held thereby in cleavagearrest until hatching time. Markers characteristic of tissue differentiation during normal embryonic and larval stages ofCiona intestinalis were expressed in muscle and two brain cell lineages of cleavage-arrested whole embryos and in epidermal and notochordal cell lineages of cleavage-arrested partial embryos. These features were muscle myofilaments and myofibrils, melanosomes of the brain pigment cells, cilium-derived structures present in a proprioceptive brain cell, extracellular test material of epidermal cell origin, and the sheath filaments, membrane leaflets, and vacuolar colloid associated with notochord cells. All of these ultrastructural markers of differentiation were blocked in their development by treatment of gastrula stage embryos with actinomycin D, an inhibitor of RNA synthesis, and presumably result from the expression of new gene activity. At the time of cleavage-arrest the five cell lineages studies still contained two or more unsegregated lineage pathways. Subsequent developmental autonomy within the lineages is consistent with the hypothesis of segregation during early development of functionally independent gene regulatory factors.     

Comparative immunocytochemical demonstration of ACTH-, LH and FSH-containing cells in the pituitary of neonatal,immature and adult rats

Summary By means of immunocytochemistry, the development of ACTH-, LH- and FSH cells was examined in the anterior pituitary of 5-day-old neonatal, 15-day-old immature and adult rats. ACTH-positive cells are angular and the periphery of these cells is strongly reactive with anti-ACTH serum. In contrast, LH- and FSH-immunopositive cells are ovoid elements, ranging in cell size and intensity of staining. Angular cells, in which only the cell periphery reacted with anti-LH serum, were observed in neonatal and immature rats; however, these cells were not stained with either anti-FSH serum or anti-ACTH serum. Observation of serial semithin sections revealed that ACTH-immunopositive cells do not react with either anti-LH or anti-FSH serum. Finally, it was observed that ACTH cells and LH cells are both functionally differentiated already in 5-day-old neonatal rats.     

The effects of Tunicamycin and 2-deoxy-D-glucose on the development ofXenopus laevis embryos

Summary Tunicamycin and 2-deoxy-D-glucose were applied toXenopus laevis embryos in the first cleavage furrow, blastula and early gastrula stages. No effect was observed with 2-deoxy-D-glucose up to the concentration 0.1 M. The effect of Tunicamycin is dose- and stage-dependent. At the concentration of 5 g/ml cleaving embryos are arrested at the onset of gastrulation and their cells exhibit decreased intercellular adhesivity, while embryos treated in the blastula and early gastrula stages may develop up to the late neurula and tail-bud stage, respectively. Higher concentrations (up to 20 g/ml) drastically affect cleavage. Concentrations of 4 to 1 g/ml allow embryos to develop up to more advanced stages; however, developmental defects are the rule. Concentrations of less than 1 g/ml do not affect development.     

M line appearance in developing striated muscle

Summary Myofilament assembly occurs in a definite sequence. Myofibrils first appear within embryonic myotomes as non-striated, linear arrangements of parallel thick and thin myofilaments (crude sarcomeres) with periodic dense cross bands (Z lines). In the center of sarcomeres within these early myofibrils, faint M lines are often detected. In older embryos, after typical cross striations became apparent, the M lines can be detected bisecting each A band.Research supported by The Muscular Dystrophy Association, U.S.A.     

Cryphodera kalesari,a new heteroderid nematode species from Haryana,India

Cryphodera kalesari n. sp., recorded on Colebrookea oppositifolia Sm. from the Kalesar forests (Haryana), India, is described. Females: swollen, saccate, with two to three lip annules, with vulval lips protruding. Second stage juveniles: length 384±19 m, spear=26.5±1 m, tail 46.5±6 m, hyaline portion 21.5±2.5 m, en face dorsal and ventral arcs of head skeleton bifurcate. Males: not found.     

Doublet-split-scaling of correlation integrals in non-linear dynamics and in neurobiology

The search for the low-dimensional attractor behaviour and the dynamic self-organization of neuronal systems, from an analysis of electroencephalographic (EEG) signals, must be carried out under conditions in which the signals are not stationary for more than a few seconds. We employ a technique that we have introduced for analyzing short signals obeying a differential equation and develop it further. The technique uses the fact that in plots of slope curves of d log C(r)/d log r against log C(r), C(r)=correlation integral, for short time sequences, the dynamics may be trans-embedding-scaled, i.e. a horizontal power-law structure builds up, that is constructed from different slope curves (different embeddings), and appears at the right value of the correlation dimension, although no single slope curve exhibits scaling.Patterns of the family of slope curves are described exhibiting the doublet-split-scaling of the correlation integrals. Examples include a solution of the Mackey and Glass delay differential equation and EEG signals. The two components of a doublet differ in the dimensions of the embeddings of which they are formed, i.e. low- and high-dimensions, respectively. The advantages subsequent to recognizing trans-embedding-scaled correlation integrals and doublet-split-scaling are illustrated for EEG delta sleep signals, with emphasis on ideal doublet-split-scaling. Unambiguous evidence of attractor behaviour in delta sleep is presented.     

The MHC haplotypes of the chicken

The major histocompatibility complex (MHC) of Gallus gallus is the B complex of which three classes of cell-membrane antigens have been clearly defined by serological, histogenetic, and biochemical methods. Two of these classes are homologous to classes I and II of mammals (B-F and B-L, respectively), while the third (B-G) is a differentiation antigen of the erythroid cell-line; the mammalian homologue of this class is still undefined. The B haplotypes comprise at least one gene of each class that displays linkage disequilibrium of a remarkable strength. The present work is the first systematic comparison by serological and histogenetic methods of the allelic products (allomorphs) of 15 haplotypes, including all of the 11 that were accepted as standard B haplotypes at the recent international Workshop on the chicken MHC in Innsbruck, Austria. The analysis has revealed many similarities, but only four pairs of probable identities: G2 and G12, F4 and F13, L4 and L13, L12 and L19. It appears therefore that the B-G locus is comparable in its degree of polymorphism to the class I (B-F) locus. The standard haplotypes are almost all of White Leghorn derivation, and preliminary typings of other breeds of chickens, and of wild chickens, indicate the existence of a much wider spectrum of allomorphs.     

Cellular hypertrophy in cardiomyopathic patients is associated with lower creatine-stimulated mitochondrial respiration

The mitochondrial respiration rate and morphometric indices in endomyocardial biopsy samples were measured in 43 patients with dilated cardiomyopathy selected in accordance to WHO criteria by endomyocardial biopsy studies after excluding of various forms of myocarditis, alcoholic cardiomyopathy and other specific diseases of the heart. A group of 13 patients with unusually high mean myocyte diameter, 30±4 m, and nuclear size, 57±5 m, was selected. The remainder of patients (n=30) had significantly lower mean myocyte diameter and nuclear size, 23±3 and 42±6 m, respectively, (p<0.01). Creatine-stimulated elevation in mitochondrial respiration rate as measured in saponin-skinned was found in the former group to be much lower (36±4%) as compared with the remainder (90±12%). Also, the former group of patients had higher left ventricular enddiastolic pressure and volume index with concomitantly decreased ejection fraction. The results indicate that marked nuclear and cellular hypertrophy is associated with lower creatine-stimulated mitochondrial respiration rate and more severe cardiac failure. They suggest that disorders in energy supply to myofibrils may be related to disturbances in cellular genetic apparatus.     

Myofibrillar adaptations during cardiac hypertrophy

The main purpose of this study was to determine the transmural adaptive changes that occur in cell size, myofibrils, and myosin isoforms from the endocardium (ENDO) to the epicardium (EPI) of the left ventricle (LV) of the rat heart during compensatory hypertrophy. Hypertrophy was induced by supra-renal aortic constriction for periods of 2, 7, 15 and 30 days. Percent left ventricular hypertrophy averaged 63±9.7% at 30 days following constriction. A significant (p <0.05) transmural gradient in the V₃ myosin isoform (9±0.7% ENDO vs. 5±1.8% EPI) was initially observed at 7 days and was still evident by 30 days (25±3.6% ENDO vs 15±2.0% EPI). Cell cross-sectional area was also greater (p <0.05) in the ENDO than in the EPI at 7,15 and 30 days. MF diameter was determined only at 30 days and was found to be similar to control values in both the hypertrophied ENDO (sham 1.24±0.05 vs hyp 1.18±0.09 m) and EPI (sham 1.17±0.08 vs hyp 1.06±0.08 m). The combined effects of cardiac myocyte hypertrophy with no change in MF diameter resulted in a calculated increase of approximately 70% in the number of myofibrils per myocyte both in the ENDO and EPI. It was concluded that the adaptive strategy of the left ventricular free wall to pressure overload was to initially increase myocyte cross-sectional area and then switch myosin expression from V₁ to V₃, both of which proceeds transmurally from the sub-endocardium towards the sub-epicardium. Along with these transmural adaptations, myofibrils increased in number while maintaining myofibrillar diameter with the apparent intent of conserving diffusion distance for calcium from the sarcoplasmic reticulum to the innermost contractile filaments of the myofibrils.