bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural features and functions of principal cells of the intermediate zone of the epididymis of adult rats
Authors: Hermo L.
Published: February 2005

Background: In the present study, principal cells of the intermediate zone of the epididymis, an area situated between the initial segment and proximal caput, were observed to present morphological features distinct from those of principal cells of other regions.

Methods: The epididymides of adult rats were fixed by perfusion with glutaraldehyde and embedded in Epon. Administration of fluid phase tracers was performed in the case of several animals. Localization of anti‐SGP‐2 and anti‐immobilin antibodies in conjunction with light (LM) and electron (EM) microscope immunocytochemistry was also performed.

Results: In the LM and EM, the most distinctive feature of many principal cells of this zone was the presence of apically located vacuoles referred to as giant endosomes due to their large size and because they readily incorporated tracers introduced into the lumen of the epididymal duct and were acid phosphatase‐negative, Giant endosomes, containing electron‐dense granular patches, appeared to form by the progressive fusion of small, medium, and large endosomes. In the supranuclear region, multivesicular bodies (MVBs) and lysosomes were present. Although smaller in size than the giant endosomes, MVBs and lysosomes contained the electron‐dense patches. It is suggested from morphological images that giant endosomes fragment into smaller units corresponding to MVBs which gradually transform into lysosomes. Experiments using anti‐SGP‐2 and anti‐immobilin antibodies revealed gold particles over the Golgi apparatus and secretory vesicles (150–300 nm) of principal cells of this zone as well as the luminal contents indicative of secretion of these proteins. Interestingly, giant endosomes were also immunolabeled with both antibodies as were stereocilia, coated pits and vesicles, and endosomes of various sizes; lysosomes were minimally labeled. These results suggest that principal cells of the intermediate zone endocytose as well as secrete SGP‐2 and immobilin. The internalized SGP‐2 and immobilin may correspond to that secreted further upstream and that, possibly due to their short half‐life and terminated function, are removed from the lumen of the duct. Principal cells of this zone secrete these proteins possibly to replenish that lost by endocytosis.

Conclusions: Principal cells of the intermediate zone contain giant endosomes. The presence of such large structures suggests that the early events in endocytosis is a slower process in principal cells of this zone as compared to other regions. The fact that these cells both secrete and endocytose SGP‐2 and immobilin adds to the complexity of our understanding of how principal cells function along the length of the epididymis. © 1995 Wiley‐Liss, Inc.
Linear gap and tight junctional assemblies between capillary endothelial cells in the eel rete mirabile
Authors: Wagner Roger , Kachar Bechara
Published: February 2005

Background: Interendothelial tight junctions and gap junctions have been described in large blood vessels and in cultures of endothelium derived from large blood vessels. Transfer of microinjected smallmolecular weight tracers between adjacent endothelial cells also has been demonstrated indicating the presence of gap junctional interendothelial communication. Similar transfer of tracers is evident between microvessel endothelial cells in culture and in microvessels in situ. However, gap junctions have not been detectable by electron microscopy of intact capillary systems. This may be due to limited sampling available in diffuse capillary systems and a small area of overlap between adjacent endothelial membranes.

Methods: Thin slices of the parallel, tightly packed capillary bed of the eel rete mirabile were cryofixed and prepared for conventional TEM by freeze substitution. Other samples were freeze‐fractured and replicated for examination of endothelial junctional components.

Results: A novel tight‐gap junctional complex between rete capillary endothelial cells is described. In freeze‐fracture replicas of the membrane P face, rows of gap junction subunits are flanked on either side by linear depressions representing grooves previously occupied by tight junctional strands that partition to the E face. In thin sections, the junctions appear in profile as short lengths of closely apposed membranes characteristic of gap junctions.

Conclusions: The tight junctional components imply a barrier to paracellular transport across the capillary wall between the endothelial cells. The gap junctional component may provide a mechanism for communication between endothelial cells along the length of the vessel wall. © 1995 Wiley‐Liss, Inc.
Distribution and colocalization of NADPH‐diaphorase activity, nitric oxide synthase immunoreactivity, and VIP immunoreactivity in the newly hatched chicken gut
Authors: Balaskas Christos , Saffrey M. Jill , Burnstock Geoffrey
Published: February 2005

Background: The distribution and colocalization of nitric oxide synthase and NADPH‐diaphorase have been investigated quite extensively in the mammalian gut; however, no such study has been under‐taken in the avian gut. In the present report, we have therefore studied the distribution and coexpression of nitric oxide synthase (NOS), NADPH‐diaphorase, and vasoactive intestinal polypeptide (VIP) in enteric neurons of the newly hatched chicken gut.

Methods: Immunohistochemical methods were used to detect NOS immunoreactivity (NOS‐IR) and VIP immunoreactivity (VIP‐IR). NADPH‐diaphorase activity was detected using a histochemical technique.

Results: Neurons expressing NADPH‐diaphorase activity, NOS‐IR, and VIP‐IR were detected in both the myenteric and submucous plexus of all regions of the gastrointestinal tract examined. All NADPH‐diaphorase positive neurons were also NOS‐IR and all NOS‐IR neurons were NADPH‐diaphorase positive, in both plexuses, indicating that NADPH‐diaphorase can be used as a marker for NOS containing neurons in the chicken gut. The majority of VIP‐IR neurons also expressed NADPH‐diaphorase activity. Only few neurons that expressed NADPH‐diaphorase activity did not express VIP‐IR. The proportion of VIP immunopositive neurons that were NADPH‐diaphorase negative increased anally and these neurons were more prominent in the submucous than the myenteric plexus ganglia. NADPH‐diaphorase positive, NOS‐IR, and VIP‐IR nerve fibres were detected in the circular muscle, but very few, if any, were present in the longitudinal muscle. VIP‐IR, but not NOS‐IR or NADPH‐diaphorase activity, was detected in mucosal fibres, in contrast to the situation in the mammalian gut.

Conclusions: These results indicate that in birds, as in mammals, nitric oxide may play a role in the neural control of the gut musculature, but that it is unlikely to be involved in the nervous control of mucosal activity. © 1995 Wiley‐Liss, Inc.
Gemelli and obturator internus muscles: Different heads of one muscle?
Authors: Shinohara Harumichi
Published: February 2005

Background: The superior gemellus, inferior gemellus, and obturator internus muscles were once regarded as a single muscle judging from their insertion and function. However, current textbooks of anatomy do not treat them as one muscle. In gross anatomy, the classification of muscles depends largely upon the nerve supply, so that the present author re‐examined the nerve supply to the three muscles.

Methods: Fourteen nerve‐muscle specimens were taken from 12 cadavers (five males and seven females) and examined with the unaided eye and under a dissecting microscope.

Results: (1) The modes of nerve supply to the superior gemellus, inferior gemellus, and obturator internus muscles differed; however, the nerves to the muscles shared the same spinal nerve components. (2) The gemelli formed a muscular pocket (“gemellus pocket”) through which obturator internus muscle passed.

Conclusions: In light of this knowledge on nerve muscle relationships, the difference in the pattern of nerve supply to the superior gemellus, inferior gemellus, and obturator internus muscles cannot be the basis for stating that the muscle are independent. Rather, their fusion to form the gemellus pocket and their common insertion suggest that they are different heads of one muscle. © 1995 Wiley‐Liss, Inc.
Bone histomorphometric changes in the femoral neck of aging and ovariectomized rats
Authors: Yamamoto Noriaki , Jee Webster S. S. , Ma Yan Fei
Published: February 2005

Background: This study characterizes the changes in cortical and cancellous bone and cross sectional moment of inertia of the femoral neck from aging and ovariectomized (ovx'd) rats to determine their role in the previously reported ovx‐induced reduction of mechanical strength in the femoral neck.

Methods: Undecalcified double‐fluorescent lableled cross sections of femoral neck of 3.5‐, 5.5‐, 6.5‐, and 8.5‐month‐old female rats and rats ovx'd at 3.5 months for 2, 3, and 5 months of 45 rats were studied. The estimated endocortical and trabecular surfaces, cortical and cancellous bone histomorphometry, and cortical moment of inertia were determined.

Results: The femoral neck was adding cortical bone between 3.5 and 5.5 months of age by increasing cortical thickness and decreasing marrow cavity area. No change of cortical bone mass was found between 5.5 and 8.5 months and the same amount of cancellous bone was observed between 3.5 and 8.5 months of age. Ovariectomy‐induced cancellous, but not cortical bone loss. The loss was due to a transient ovx‐induced negative bone balance that by 5 months post‐ovx produced a 42% loss in trabecular bone while the histomorphometry profiles were the same as controls. The crosssectional moment of inertia increased with age but did not differ significantly between ovx'd and controls.

Conclusions: Our findings suggest that the ovx‐induced cancellous bone loss could be a contributing factor to the reduced mechanical strength in the femoral neck of ovx'd rats reported previously. © 1995 Wiley‐Liss, Inc.
Architecture of the synovial vasculature in rabbit knee joints studied by scanning electron microscopy
Authors: Funk R. H. W. , Brosche Ch. , Tittor F.
Published: February 2005

Background. Although numerous studies about the synovial vasculature exist, reports about the three‐dimensional architecture of the synovial vasculature with special respect to the regional differentiations are still lacking.

Methods. The synovial vasculature in the knee joint of six albino rabbits was investigated using scanning electron microscopy of vascular resin casts. In addition, histological sections were made from the decalcified knees of two rabbits.

Results. The vessels of the fibrous tissue in the joint capsule (medial and lateral parts) were arranged in two layers; a synovial layer with arteriovenous anastomoses and a layer facing the fibrous tissue with a more simply arranged vessel architecture. In the areolar (suprapatellar) pad, the vessels form a dense array of capillary loops that possess capillary arcades as arteriovenous connections and true arteriovenous anastomoses located in the deeper layer near the subsynovial tissue. Those capillaries that border the cartilage form more flattened and isolated loops. In the fatty tissue the vasculature resembles the simply arranged network of the outer layer of the fibrous tissue.

Conclusions. This first scanning electron microscopic study of the rabbit knee synovial vessels shows that each region possesses a characteristic microvascular pattern–possibly adapted to the functional needs of the joint (production of synovial fluid, nourishment of the avascular tissues; maintainance of the blood flow during all joint positions). © 1995 Wiley‐Liss, Inc.
Ultrastructural quantitative analysis of the innervation of axillary lymph nodes in juvenile and old rats
Authors: Novotny G. E. K. , Schöttelndreier A. , Heuer T.
Published: February 2005

Background: Earlier studies have shown that the innervation of axillary lymph nodes is increased in old animals, compared to juvenile rats. The question thus arose, whether changes are also observable at an ultrastructural level for varicosities which form the actual transmission units.

Methods: Ensheathed (axons) and unensheathed axonal profiles (open areas), were quantified with their spatial relationships to cells at the ultrastructural level in the axillary lymph nodes of juvenile ( < 6 weeks) and old ( > 2 years) Wistar rats.

Results: In both groups of animals the majority of open areas, irrespective of their content of vesicles, lie at distances of more than 1,000 nm from cells in the plane of the section. Almost all open areas, located within 1,000 nm of a cell, are related to reticular cells, a small minority to plasma cells, and even fewer to lymphocytes. In the old animals there is a highly significant increase in the total number of sections of open areas with and without vesicles per unit area of medulla. The number of open areas related to cells does not change significantly in the old animals, as also the percentage of profiles containing vesicles. Only the percentages of open areas with and without vesicles related to plasma cells increase significantly in the old animals. This change is paralleled by a highly significant increase in the percentage volume of plasma cells in the old animals. On average, the profiles related to cells are closer to the cells in the older animals.

Conclusions: The observed changes indicate that the innervation of lymph nodes of the rat is absolutely increased in the old animals, but that the relations between the various categories of profiles and their relations to cells tend to remain constant. © 1995 Wiley‐Liss, Inc.
Ontogeny of sensory nerves in the developing skeleton
Authors: Sisask G. , Bjurholm A. , Ahmed M. , Kreicbergs A.
Published: February 2005

Background: Previous studies have shown that the neuropeptide calcitonin gene‐related peptide (CGRP) have an influence on osteoclastic bone resorption and that CGRP and substance P (SP), both wellknown markers for sensory neurons, behave as growth factors.

Materials and Methods: The ontogeny of the sensory nerves in the hindlimb skeleton of the rat was studied from gestational day (GD) 15 to neonatal day (ND) 24 by immunohistochemistry. Neurofilaments and nerve terminals were labelled with protein gene‐product 9.5 (PGP 9.5) and synaptophycin (SYN) respectively.

Results: PGP 9.5 appeared at GD 15 and SYN at GD 19, both in the perichondrial tissue of the long bones. One week later, at ND 4 nerve fibre, immunoreactive to PGP 9.5 and SYN were observed within the bone organ. Sensory nerves, indicated by CGRP and SP, were first discerned at GD 18–19 in the periosteal tissue of the diaphyseal and metaphseal regions and in the bone organ at ND 4. Approximately at ND 6, vascular as well as non‐vascular nerves extended into the metaphyses and at ND 8 into the epiphyses, concomitant with the first signs of mineralization.

Conclusions: The study shows that a functional sensory nerve supply of the developing bone organ occurs immediatly prior to partus, apparently parallel with an increasing mineralization. The combined findings may indicate a sensory influence on developmental processes in the skeleton. © 1995 Wiley‐Liss, Inc.
Thyroid gland development in the brushtail possum, Trichosurus vulpecula
Authors: Buaboocha W. , Gemmell R. T.
Published: February 2005

Background: The onset of thyriod function occurs at different times with respect to birth in different mammals. In most marsupials studied thus far, thyroid function begins during the latter half of pouch life. However, in marsupials, thyroxine can be transported from the mother to the young via milk. In this study the plasma concentration of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3), in the young was correlated with the ultrastructural appearance of the thyroid of the young.

Methods: Thyroid glands at 40, 65, 70, 96, 113, 115, and 129 days postpartum and from an adult were examined with the light and electron microscope. Plasma concentrations of both T4 and T3 in young possums were determined by radioimmunoassay.

Results: Plasma concentrations of T4 in the young were less than 10 ng/ml prior to day 60 and 12 ng/ml on day 60; they rose to a peak of 45 ng/ml on day 120 postpartum and then diminished to below 10 ng/ml by day 160 postpartum. Plasma T3 concentrations were similar in profile, the peak concentration being 0.25 ng/ml on day 120 postpartum, and, as with T4, T3 concentrations decreased in the latter part of the lactation period. The morphology of the follicular cells of the thyroid gland would suggest that the developing brushtail possum is capable of producing thyroxine at about day 65 postpartum. Densely staining bodies, presumably lysosomes that are required for the conversion of thyroglobulin to thyroxine, were first seen on day 65, and greater quantities were noted in day 96, 113, 115, and 129 thyroid tissue.

Conclusions: The plasma concentrations of T4 and T3 of the young are greater than that of the adult by day 60 postpartum, with peak concentrations of thyroid hormones on day 120 postpartum. Ultrastructural examination would suggest that the possum thyroid gland is capable of producing thyroid hormones at about day 65 postpartum. The activation of the thyroid gland precedes the reported increase in growth rate of the young possum on day 96 (Gemmell and Hendrikz, 1993. Aust. J. Zool., 41:141 – 149 ). © 1995 Wiley‐Liss, Inc.
Venous structures associated with thermoregulation of phocid seal reproductive organs
Authors: Rommel Sentiel A. , Early Greg A. , Matassa Keith A. , Pabst D. Ann , McLellan William A.
Published: February 2005

Backgound: Seal reproductive systems are surrounded by thermogenic muscle and insulating blubber, suggesting elevated temperatures at the gonads and uterus. In the limbs of terrestrial mammals, cooled blood returning from superficial veins is mixed proximally with warm blood returning from deep veins. Thus, mixed cool‐superficial and warmdeep venous blood from the hind limbs is returned to the central circulation.

Methods: We describe structures observed in salvaged carcasses of harbor (Phoca vitulina), gray (Haliochoerus gryphus), harp (Phoca groendlandica), hooded (Cystophora cristata), and ringed (Phoca hispida) seals. Vessels were identified by dissection of injected and uninjected material.

Results: In contrast to terrestrial mammals, phocid seals have anastomoses between the veins of the distal hind limb and the pelvis which allow large volumes of cool blood returning from the skin surface of the flipper to enter the gluteal, pelvic, or pudendo‐epigastric veins. This provides a cool‐superficial venous return that remains separate from the warm‐deep venous return of the femoral veins. The cooled venous blood from the hind flippers supplies venous plexuses lining the inguinal region and the abdominal and pelvic cavities.

Conclusions: Cooled blood may prevent hyperthermic insult to seal reproductive systems. © 1995 Wiley‐Liss, Inc.
Tissue differentiation and correlated changes in enzymatic activities during primary antler development in fallow deer (Dama dama)
Authors: Szuwart Thomas , Kierdorf Horst , Kierdorf Uwe , Althoff Jörg , Clemen Günter
Published: February 2005

Background: Deer antlers are useful models for studying bone growth and biomineralization in mammals. To achieve a better understanding of the mechanisms underlying the formation of primary cranial appendages in deer, the present study relates the histogenesis of primary antlers to changes in enzymatic (phosphatase) activities in the different tissue zones of this organ.

Methods: The growing tips of the primary antlers (4.3 to 5 cm in length) were removed from five fallow bucks, aged about 10 months. Part of the material was processed for light microscopy. The other part was cryofixed, and the different histologically defined regions were analyzed for the activities of alkaline phosphatase (ALP) and tartrate‐resistant acid phosphatase (TRAP) as well as for the concentrations of inorganic and organic phosphate.

Results and Conclusions: Histologically, the primary antler could in distoproximal direction be divided into eight different zones (dermis; perichondrium; zones of cartilage formation, hypertrophy, mineralization, and degeneration; primary spongiosa; secondary spongiosa). The histological results demonstrate that the elongation of the primary antler proceeded through a modified form of endochondral ossification, resembling that seen during formation of pedicles and secondary antlers. The concentrations of the extractable activities of ALP and TRAP progressively increased from the perichondrium to the zone of cartilage mineralization. Thus, highest activity of TRAP during primary antler formation occurred at an earlier stage of tissue differentiation than in somatic endochondral ossification, where the enzyme is a biochemical marker of osteoclastic activity during bone remodeling. The present results might reflect the presence of osteoclastic precursor cells in the zone of cartilage mineralization as an adaptation to the rapidity of antler growth. Our findings of the contents of extractable ALP, inorganic and organic phosphate in the different tissue zones of the developing primary antler are in good agreement with previous studies analyzing epiphyseal growth plates and point to the fact that ALP causes a rise in inorganic phosphate and the removal of inhibitors for mineralization, like pyrophosphate. © 1995 Wiley‐Liss, Inc.
Cellular distribution patterns of lanthanum and morphometry of rat hearts exposed to different degrees of ischemic stress
Authors: Schmiedl A. , Bach F. , Fehrenbach H. , Schnabel Ph. A. , Richter J.
Published: February 2005

Background: The element lanthanum (La) can be used as a tracer for verification of membrane permeability. The aim of this study was to establish whether (1) distribution of La in the myocardium of rat hearts depends on the degree of ischemic stress and (2) morphometrically determined cell and mitochondrial swelling correlates with the La distribution.

Materials and Methods: Isolated beating rat hearts were arrested by coronary perfusion with the cardioplegic solution Custodiol® (controls) or by aortic cross clamping followed by exposur to different degrees of ischemic stress. The solutions for perfusion‐and postfixation as well as for rinsing contained 1.1% La(NO3)3. Cellular and mitochondrial swelling were determined morphometrically and myocytes exhibiting intracellular La were quantified and stated as percentage of test fields.

Results: Immediately after cardiac arrest La was present as precipitates only in a few myocytes adjacent to the outer mitochondrial membrane as seen by cTEM and ESI. In such cells La was also detected by EELS in mitochondrial matrix and myofibrils. Advanced ischemic stress led to an increase of the percentage of myocytes containing detectable intracellular La. After 45 min ischemia at 30°C, myocytes and mitochondria showed a remarkable edema and different intracellular distribution patterns of La. After 90 min of ischemia at 20°C interruptions of sarcolemma could only be detected in a few of the swollen myocytes. Roundish La granules were seen in the myofibrils. The percentage of myocytes containing intracellular La and the extent of cellular and mitochondrial swelling showed a significant correlation.

Conclusions: Patterns of intracellular La distribution depend on the degree of ischemic stress and correspond to the degree of cellular as well as mitochondrial edema. These results point at a direct relation between alterations of membrane permeability and development of edema. © 1995 Wiley‐Liss, Inc.
Ultrastructure and cytochemical staining characteristics of canine natural killer cells
Authors: Knapp Deborah W. , Turek John J. , Denicola Dennis B. , Chan Thomas C. K. , Carter Wayne O. , Snyder Paul W. , Robinson J. Paul
Published: February 2005

Background: The purpose of this work was to describe the ultrastructure and cytochemical staining characteristics of canine peripheral blood lymphocytes with natural killer (NK) cell activity, with comparison made to non‐NK lymphocytes.

Methods: Canine lymphocyte populations evaluated for ultrastructure, cytochemical staining, and NK function (by 51 chromium release assay) included: peripheral blood lymphocytes; lymphocytes from band 1 (NK‐enriched), band 2, and the pellet of a 45/50% percoll gradient; lymphocytes from the supernatant fluid (non‐conjugated lymphocytes) and pellet (lymphocytes conjugated to tumor cell targets) of a 17% percoll gradient; and null (CD4−CD8−) and CD4−CD8+ lymphocytes.

Results: NK activity was concentrated in band 1 lymphocytes of the 45/50% percoll gradient with further enhancement of activity occurring in sorted null cells. Canine NK cells were 5.5 to 6.5 μm in diameter with a reniform (kidney bean shape) nucleus, and electron‐dense cytoplasmic granules. NK cells (percoll band 1 cells and null cells) had larger cell and nuclear area, and less round nuclei when compared to non‐NK lymphocytes. The overall cytochemical staining (chloracetate esterase, peroxidase, sudan black B, naphthyl acetate esterase, naphthyl butyrate esterase periodic acid‐Schiff stain, and acid phosphatase with and without tartrate) pattern was similar in all the lymphocyte populations evaluated.

Conclusions: This work confirms the usefulness of a 45/50% percoll gradient in obtaining a NK‐enriched fraction of canine lymphocytes, and shows further enhancement of NK activity in sorted CD4−CD8− cells. The ultrastructure of canine NK cells is similar to that reported for human NK cells, but is different from that of other canine peripheral blood lymphocytes. Standard cytochemical staining does not discriminate canine NK cells from other lymphocytes. © 1995 Wiley‐Liss, Inc.
Fibrous architecture of the dorsal aponeurosis of the thumb
Authors: Bade Holger , Krolak Christoph , Koebke Jürgen
Published: February 2005

Background: The extensor apparatus of the thumb displays obvious structural variations in its proximo‐distal expanse. Its associated tissue comes in close relation to the dorsal aponeurosis that have varying topographical relationships to the extensor apparatus of the thumb. This region is especially important as the location of pathological and repair processes.

Methods: In this anatomical study using a modified embedding technique a histological description of the fibrous architecture of the dorsal aponeurosis and the peritendinous connective tissue body of the thumb is presented.

Results: The dorsal connective tissue of the thumb forms different layers of collagen lamellae as a peritendinous system around the tendons of the long and short extensor tendons of the thumb. This peritendinous laminar system as the main part of the dorsal aponeurosis is connected with both the capsular and the retinacular ligaments of the thumb.

Conclusions: It will be shown that the structural variations of the dorsal aponeurosis and peritendinous connective tissue are an expression of different topographical zones of stress along the lines of a balanced musculofibrous stabilization of the interphalangeal joint of the thumb. The expansions in the peritendinous intercellular space act as defined gliding spaces or clefts of the extensor apparatus. © 1995 Wiley‐Liss, Inc.
Physiological response of central metabolism inEscherichia colito deletion of pyruvate oxidase and introduction of heterologous pyruvate carboxylase
Authors: Vemuri G.N. , Minning T.A. , Altman E. , Eiteman M.A.
Published: February 2005

We studied the physiological response ofEscherichia colicentral metabolism to the expression of heterologous pyruvate carboxylase (PYC) in the presence and absence of pyruvate oxidase (POX). These studies were complemented with expression analysis of central and intermediary metabolic genes and conventional in vitro enzyme assays to evaluate glucose metabolism at steady‐state growth conditions (chemostats). The absence of POX activity reduced nongrowth‐related energy metabolism (maintenance coefficient) and increased the maximum specific rate of oxygen consumption. The presence of PYC activity (i.e., with POX activity) increased the biomass yield coefficient and reduced the maximum specific oxygen consumption rate compared to the wildtype. The presence of PYC in apoxBmutant resulted in a 42% lower maintenance coefficient and a 42% greater biomass yield compared to the wildtype. ProvidingE. coliwith PYC or removing POX increased the threshold specific growth rate at which acetate accumulation began, with an 80% reduction in acetate accumulation observed at a specific growth rate of 0.4 h−1in thepoxB‐pyc+strain. Gene expression analysis suggests utilization of energetically less favorable glucose metabolism via glucokinase and the Entner‐Doudoroff pathway in the absence of functional POX, while the upregulation of the phosphotransferase glucose uptake system and several amino acid biosynthetic pathways occurs in the presence of PYC. The physiological and expression changes resulting from these genetic perturbations demonstrate the importance of the pyruvate node in respiration and its impact on acetate overflow during aerobic growth. © 2005 Wiley Periodicals, Inc.
Electrical response and function of a bitter substance receptor associated with the maxillary sensilla of the larva of the silkworm, Bombyx mori L.
Authors: Ishikawa Shigeo
Published: February 2005

This receptor was strongly stimulated by “bitter” substances such as strychnine nitrate, salicin, brucine, nicotine, etc. as well as by the aqueous extracts which were obtained from many normally unacceptable plant leaves for the larvae. Such bitter substances for human sense as phenylthiourea, betaine, and MgSO4 were inert.

This maxillary hair associates a water receptor (W) and two salt receptors (N2 and N2′) as well as the R receptor.

When a solution contained both bitter substance and NaCl, the respective substance had a synergistic effect on N2 + N2′ or R receptor activities in a certain concentration range of each compound. Responsiveness of the R or N2 + N2′ receptors seemed to depend on the the mixing ratio of the two compounds. CaCl2 had inhibitory effects on the activity of the R and W receptors, but not on those of the N2 and N2′ receptors. Sugars had no effect on R receptor activity.

The inhibitory effect on the feeding was observed when the substance stimulating the R receptor was present in either filter paper or fresh leaves. The inhibitory effect was considerably lessened by inactivation of the R receptor neuron.

Accordingly, it is supposed that the exclusion of botanical species from the food plant range of the silkworm larvae might be determined in some parts by a high frequency of occurrence of the specific stimuli for the R receptor in their leaves.
Sialic Acid of Mammalian Cell Lines
Authors: Kraemer Paul M.
Published: February 2005

Approximately two‐thirds of the total sialic acid (S.A.) per cell of a number of cell lines (L‐929, L5178Y, HeLa, C13, P183, and CHO) was located at the cell surface but was inaccessible to the action of trypsin, pronase, lysozyme, β‐glucuronidase, or hyaluronidase. The mean surface density of S.A. ranged from 5.4 × 105 molecules/μ2 surface area for the L5178Y cell to 16.1 × 105 molecules/μ2 for the P183 cell. The P183 cell line, which is a polyoma virus‐transformed derivative of Stoker's C13 line, consistently contained more S.A. per cell than the latter under a variety of growth conditions, although the two lines did not differ in mean cell volume. When mean cell volume of C13, P183, or CHO cells was experimentally manipulated by thymidine or colcemide blockade, S.A. content per cell followed size changes closely. No evidence could be found for a shift in total S.A. per unit cell volume accompanying the period of maximum mitotic activity of partially synchronized CHO suspension cultures. Comparisons between cells grown on glass and the same cells grown in suspension, or between cells grown to different densities on glass, indicated no differences in the characteristic S.A. content per cell.
Binding of cations by microsomes from rabbit skeletal muscle
Authors: Carvalho Arselio P.
Published: February 2005

Fragmented sarcoplasmic reticulum and transverse tubular system, as isolated in the microsomal fraction from rabbit skeletal muscle, bind H+, Na+, K+, Ca++, Mg++, and Zn++. The binding depends on a cation exchange type of interaction between these cations and the chemical components of the membranous systems of the muscle cell. The monovalent and divalent cations exchange quantitatively for each other at the binding sites on an equivalent basis. Scatchard plots of the H+ binding data indicate that the binding groups can be resolved into two major components in terms of their pK values. Component 1 has a pK value of 6.6 and a capacity for H+ binding of 2.2 meq/g N. The second component has a much higher H+ binding capacity (7–8 meq/g N), but its pK value, 3.4, is non‐physiological. The binding of cations other than H+ at a neutral pH occurs at the binding sites making up component 1. The order of affinity of the cations for the microsome binding sites is H+ » Zn++ > Ca++ > Mg++ » Na+ = K+ as reflected by the apparent respective pKM values: 6.6, 5.2, 4.7, 4.2, 1.3, 1.3. Caffeine, which causes contracture and potentiates the twitch of skeletal muscle, does not interfere with the binding of Ca++ by the microsomes at neutral pH.
The release of amino acids from nerve during stimulation
Authors: Wheeler Darrell D. , Boyarsky L. L. , Brooks W. H.
Published: February 2005

Frog sciatic nerves were incubated for 24 hours in either glycine, aspartic acid, glutamic acid, lysine, leucine, γ‐aminobutyric acid, glutamine, or pentanedioic acid (all labeled with C14), and the rates of release of these compounds were monitored under resting conditions and during stimulation. Upon stimulation, the rate or release of glutamic acid increased an average of 200% above the resting rate. This extra release is highly specific with regard to molecular size and structure, since of the compounds tested only glutamic acid gave significant increases in rates of release during stimulation. Ouabain (0.1 mM) had no effect on the rate of release; however, sodium azide (0.2 mM or 1.0 mM) completely eliminated the extra release during excitation, indicating that the increased permeability to glutamic acid is energy‐dependent. Competition experiments show that the extra release of glutamic acid can be eliminated with 10 mM concentrations of non‐isotopic choline. The hypothesis is advanced that glutamic acid is actively extruded by a highly specific carrier mechanism.
A study of the crustacean axon repetitive response. III. A comparison of the effect of veratrine sulfate solution and potassium‐rich solutions
Authors: Wright Ernest B. , Tomita Tadao
Published: February 2005

The crustacean single nerve fiber gives rise to trains of impulses during a prolonged depolarizing stimulus. It is well known that the alkaloid veratrine itself causes a prolonged depolarization; and consequently it was of interest to investigate the effect of this chemically produced depolarization on repetitive firing in the single axon and compare it with the effect of depolarization by an applied stimulating current or by a potassium‐rich solution. It was found that veratrine depolarization, though similar in some respects to a potassium‐rich depolarization of depolarizing current effect, was in many respects quite different.

(1) At low veratrine concentration, less than 1 Mg%, the negative after potential following a spike action potential was prolonged and augmented. At higher concentrations or after a long period of time, veratrine caused a prolonged steady state depolarization of the membrane, the “veratrine response”. The prolonged plateau depolarization response could be elicited with or without an action potential spike by a short or long duration stimulating pulse, but only if the veratrine depolarization was prevented or offset by an applied conditioning hyperpolarizing inward current.

(2) The “veratrine response” resembled the potassium‐rich solution response in the plateau‐like contour of the depolarization and the very low membrane resistance during this plateau phase. Like the potassium response, it was possible to obtain a typical hyperpolarizing response with an inwardly directed current pulse if applied during the plateau phase. During the negative after potential augmented with veratrine, however, this hyperpolarizing response was not observed.

(3) In contrast to the potassium response, however, the “veratrine response” is intimately associated with the sodium concentration in the external medium. The depolarization in millivolts is linearly related to the log of the concentration of external sodium. Moreover, during veratrine action there is a continuous and progressive inactivation of the sodium mechanism which ultimately terminates repetitive firing and abolishes the spike action potential. Then even with conditioning hyperpolarization only the slow response may be elicited in veratrine, occasionally with a spike superimposed if sodium is present, but without repetitive firing.

(4) It is concluded that veratrine action is the result of a chemical or metabolic reaction by the alkaloid in the membrane. It is suggested that veratrine may inhibit the sodium extrusion mechanism, or may itself compete for sites in the membrane with calcium and/or sodium. This explains the inhibiting effect of high calcium, the abolition of the “veratrine response” with low temperature and high calcium combined and the progressive inactivation of the sodium system.
Metabolic control reactions of the intact urinary bladder of the toad
Authors: Canessa‐Fischer Mitzy , Davis Robert P.
Published: February 2005

Metabolic control reactions have been studied in the intact toad bladder by means of fluorescence spectrophotometric measurement of reduced pyridine nucleotide and by measurement of respiration with the platinum electrode. substrates such as pyruvate and succinate lead to prompt increases in reduction level of pyridine nucleotide with only slight acceleration of respiration. major metabolic control is exerted by adp, which depletes the intact bladder of reduced pyridine nucleotide and accelerates respiration. respiratory control ratios, as for isolated mitochondria, depend upon the substrate being metabolized. a significant fraction of added adp appears to gain entry into the intact toad bladder and is converted to atp, anaerobiosis and amobarbital lead to increased levels of reduction of pyridine nucleotide. the spectroscopic and metabolic properties of the reduced pyridine nucleotide being studied identify it with that fraction of dpnh which is bound at one of the energy conservation sites linking phosphorylation reactions with electron transfer.
Membrane permeability changes in amphibian eggs at ovulation
Authors: Morrill Gene A. , Rosenthal Jean , Watson Donald E.
Published: February 2005

Electropotential differences between the cytoplasm and external medium have been compared in the mature R. pipiens occyte and the ovulated unfertilized egg as a function of [Na]o, [K]o, [Ca]o and [Cl]o. In solutions containing 1.0 mM Ca++ the oocyte behaved as though it were predominantly permeable to K+ and Cl−, i.e., like a KCl electrode. However, the steady potential decreased with decreasing [Ca]o and in 5 × 10−4 mM [Ca]o the oocyte membrane behaved like a NaCl electrode. Studies on the steady potential as a function of [Na]o, [K]o and [Cl]o in 1.0 mM Ca++ or Ca‐free solutions suggest that Ca++ controls the passive permeability of the oocyte membrane to Na+ and Cl−. In the ovulated unfertilized egg the K+ selectivity of the cell membrane disappeared and the system behaved like a NaCl electrode. No effect of external Ca++ or K+ concentration changes on the steady potential was observed. These results indicate that the ion permeability properties of the ovulated egg are similar to that of the ovarian oocyte in Ca‐deficient medium, and suggests that the mechanism of ovulation may involve the removal of Ca++ regulation of ion permeability of the egg cell membrane.
The sodium and potassium activated atpase. II. Comparative study of intestinal epithelium and red cells
Authors: Berg G. G. , Szekerczes J.
Published: February 2005

The Na‐K ATPase found in sedimentable fractions of intestinal epithelium of rats hydrolyzed cytidine triphosphate nearly as well as ATP (25% to 50%); was active only in presence of divalent cations, with specificity for Mg (100%), Mn (50%) and Ca (10%); showed a plateau of activation when Mg concentrations were in excess of substrate; and was inhibited by a second divalent cation (Zn > Mn > Ca), and by 3 × 10−4 M ouabain (50%). Parallel assays of rat red cell ghosts showed differences in substrate specificity (CTP was not utilized), in activation kinetics (activation peak with Mg) and in greater specificity to Mg (Mn was a weaker activator and Zn was a weaker inhibitor). Stabilities also differed in the two preparations: NaK ATPase of intestinal epithelium was activated by sucrose extraction and denatured during cytolysis at room temperature, while that of red cell fragments was denatured during sucrose extraction and preserved by hemolysis at room temperature. Other properties of NaK ATPase studied in the two tissues included activation by monovalent cations (optimum at 160 mM Na, 15 mM K), specificity to monovalent cations, and sensitivity to lipid solvents and to some drugs. The data were discussed in terms of comparative properties of NaK ATPases of various cells.

Residual ATPase activities of intestinal epithelium and red cell ghosts were shown to differ in substrate specificity, inhibition and activation. “Residual ATPase” from intestinal epithelium was a zinc‐activated nucleoside polyphosphate phosphohydrolase, while ghosts contained MgATPase. Only the latter enzyme was specific to ATP and Mg, activated by Ca in presence of Mg, and sensitive to inhibition by PCMB and Zn.
Potentiation of the colchicine effect on frog melanocytes by high hydrostatic pressure
Authors: Malawista Stephen E. , Asterita Harvey , Marsland Douglas
Published: February 2005

In dermal melanocytes of Rana pipiens, colchicine is known to produce a gradual, dosage‐dependent dispersion of melanin granules, irreversible over several hours. This effect is potentiated by a number of chemical agents that normally produce a reversible dispersion of granules. In the present study we examined the effect of high hydrostatic pressure on changes induced in melanocytes by colchicine.

In Ringer's solution, samples of skin from a single frog were incubated for 30 minutes at room temperature with or without colchicine, 9 × 10−5 M. Then two samples, one of which had been pretreated with colchicine, were successively subjected to 12,000 psi for one hour at 25 to 26°C. The degree of dispersion of melanin granules in melanocytes was observed before, during and after the period of pressure.

In frog skin pretreated with colchicine, the usually gradual, irreversible dispersion of melanin granules in melanocytes was potentiated.

Since high pressure is known to produce solational changes in protoplasm, such changes may accompany dispersion of melanin granules in melanocytes. If this be so, then sol‐gel equilibria may be important in the action of dispersing and aggregating agents, many of which are hormones and other physiologically active agents. Finally, the present study supports the hypothesis that colchicine shifts protoplasmic sol‐gel equilibria toward a less gelated condition.
Effect of halothane anesthesia on extravascular mobilization of neutrophils
Authors: Bruce David L.
Published: February 2005

The ability of neutrophil leukocytes to extravasate into the peritoneal cavity in response to an intraperitoneal injection of bacterial endotoxin was studied in mice. The normal response of a marked accumulation of intraperitoneal neutrophils was completely abolished by halothane anesthesia. It was further shown that such abolition depended upon the presence of halothane duringthe time the extravasation would normally be occurring. The evidence points toward an effect on either the leukocyte or the vessel rather than a non‐specific “stress” effect. It is suggested that the effect is on the neutrophil, rendering it less deformable and, hence, less able to undergo trans‐vascular diapedesis.
The effect of erythropoietin on the growth and development of spleen colony‐forming cells
Authors: Schooley John C.
Published: February 2005

The progressive growth and development of spleen colonies was studied in heavily irradiated host mice in which erythropoiesis was modified by various procedures. Erythropoietic activity in non‐polycythemic hosts bearing spleen colonies was not increased by injections of exogenous erythropoietin. Detectable levels of erythropoietin were found in the heavily irradiated host mice suggesting that the failure of exogenous erythropoietin to modify erythropoiesis was because the host mice were already maximally stimulated by the high endogenous erythropoietin levels.

Spleen colonies do not become erythroid in polycythemic mice. The injection of exogenous erythropoietin into heavily irradiated polycythemic hosts did not decrease the total number of spleen colonies produced by a given bone marrow transplant, as would be expected if erythropoietin acted directly on the colony‐forming cells. Comparison of growth curves for colony‐forming cells in the spleens of polycythemic hosts either receiving or not receiving erythropoietin indicated that the overall doubling time of colony‐forming cells during the first ten days after transplantation was not changed by the daily injection of erythropoietin.

These experiments are consistent with the concept that erythropoietin is necessary for the development of erythroid colonies. Erythropoietin acts upon some progeny of the colony‐forming cell rather than the colony‐forming cell itself.
The cellular composition of hemopoietic spleen colonies
Authors: Fowler J. H. , Wu A. M. , Till J. E. , McCulloch E. A. , Siminovitch L.
Published: February 2005

The cellular composition of individual hemopoietic spleen colonies has been studied using techniques which tested primarily for cell function rather than cell morphology. Erythroblastic cells were recognized by their capacity to incorporate radioiron, granulocytic cells by their content of peroxidase‐positive material, and hemopoietic stem cells by their ability to form spleen colonies in irradiated hosts. It was found that, 14 days after the initiation of spleen colonies, the distribution of these cell types among individual colonies was very heterogeneous, but that most colonies contained detectable numbers of erythroblasts, granulocytes and colony‐forming cells. An appreciable proportion of the cells in the colonies could not be identified as any of these three cell types. No strong correlations between numbers of erythroblasts, granulocytes and colony‐forming cells in individual colonies were observed, though there was a tendency for colonies containing a high proportion of erythroblasts to contain a low proportion of granulocytes, and for colonies containing a high proportion of granulocytes to contain a higher proportion of colony‐forming cells. An analysis of colonies which contained cells bearing radiation‐induced chromosomal markers indicated that 83–98% of the dividing cells within 14‐day spleen colonies were derived from single precursors.