Muscle capillary supply in hind limb and diaphragm of the common shrew (Sorex araneus)

Shrew species of the subfamily Soricinae have unusually high metabolic rates when compared to Crocidurinae shrews and other similar-sized mammals. The aim of this study was to clarify whether the high basal metabolic rate of Soricinae shrews is reflected in a high capillary density in their muscles. To this end, the capillary supply of four limb muscles and diaphragm of the common shrew (Sorex araneus) was quantified from cross-sectioned muscles. The capillary densities of the limb muscles were 2575 ± 329, 3111 ± 299, 2812 ± 197 and 2752 ± 173 capillaries mm⁻² fibre area in gastrocnemius lateralis, g. medialis, plantaris and soleus, respectively. Capillary density of the shrew diaphragm (6691 ± 1057) was double that of the limb muscles. This value is among the highest ever measured in mammals. In general, the capillary supply in the hind limb of the common shrew is about 3–4 times higher than commonly found in the leg muscles of the laboratory rat or other bigger mammals, but similar to those in Crocidurinae shrews and some small rodents. Thus the high resting metabolism of the common shrew is not associated with an extraordinarily high capillary density. The apparent disparity between basal metabolic rate and muscle capillary supply in S. araneus is probably due to the small aerobic scope of shrews in the subfamily Soricinae. Accepted: 22 January 1998     

Voluntary running induces fiber type-specific angiogenesis in mouse skeletal muscle

Adult skeletal muscle undergoes adaptation in response to endurance exercise, including fast-to-slow fiber type transformation and enhanced angiogenesis. The purpose of this study was to determine the temporal and spatial changes in fiber type composition and capillary density in a mouse model of endurance training. Long-term voluntary running (4 wk) in C57BL/6 mice resulted in an approximately twofold increase in capillary density and capillary-to-fiber ratio in plantaris muscle as measured by indirect immunofluorescence with an antibody against the endothelial cell marker CD31 (466 ± 16 capillaries/mm² and 0.95 ± 0.04 capillaries/fiber in sedentary control mice vs. 909 ± 55 capillaries/mm² and 1.70 ± 0.04 capillaries/fiber in trained mice, respectively; P < 0.001). A significant increase in capillary-to-fiber ratio was present at day 7 with increased concentration of vascular endothelial growth factor (VEGF) in the muscle, before a significant increase in percentage of type IIa myofibers, suggesting that exercise-induced angiogenesis occurs first, followed by fiber type transformation. Further analysis with simultaneous staining of endothelial cells and isoforms of myosin heavy chains (MHCs) showed that the increase in capillary contact manifested transiently in type IIb + IId/x fibers at the time (day 7) of significant increase in total capillary density. These findings suggest that endurance training induces angiogenesis in a subpopulation of type IIb + IId/x fibers before switching to type IIa fibers. adaptation; capillary density; endothelial cells; fiber type transformation; vascular endothelial growth factor     

Oestrogen receptor β is present in both muscle fibres and endothelial cells within human skeletal muscle tissue

Oestrogen receptor β (ERβ) is expressed in human skeletal muscle tissue. In the present study, we have developed an immunohistochemical method to reveal if ERβ is located within the muscle fibres as well as within capillaries. Skeletal muscle biopsies were obtained from m. quadriceps femoris vastus lateralis in four healthy young subjects. Immunohistochemical triple staining was applied to transverse sections of paraffin-wax-embedded tissue. The basement membrane of muscle fibres and capillaries was identified by using an antibody to collagen IV, endothelial cells using an antibody to CD34 and ERβ using a corresponding antibody. The ERβ-positive (ERβ+) nuclei were located within the muscle fibre defined by the localisation of collagen IV. ERβ+ nuclei were also, for the first time, found in endothelial cells of capillaries in skeletal muscle tissue. Quantification was performed on transverse cryostat sections after performing a double staining (collagen IV and ERβ). It was shown that 24% of the ERβ+ nuclei were located within capillaries, and 76% were located within muscle fibres. In conclusion, ERβ in human skeletal muscle tissue is expressed not only in the muscle fibres themselves, but also within the capillary endothelial cells. This observation might improve understanding of the physiological role of oestrogen and its receptor.     

Effect of NaCl on kinetics ofd-glucosamine uptake in yeasts differing in halotolerance

The initial rate ofd-glucosamine uptake by the non-halotolerant yeastSaccharomyces cerevisiae was approximately halved as the apparent half saturation constant (K_m) and the apparent maximum velocity (V_max) changed from 6.6mm to 16.4mm and from 22 μmol · g⁻¹ · min⁻¹ to 16 μmol · g⁻¹ · min⁻¹, respectively, when the salinity in the medium was increased from zerom to 0.68m NaCl. Corresponding changes in a high affinity transport system in the halotolerant yeastDebaryomyces hansenii were from 1.1mm to 4.6mm and from 3.1 μmol · g⁻¹ · min⁻¹ to 4.5 μmol · g⁻¹ · min⁻¹, implying a practically unchanged transport capacity. In 2.7m NaCl, K_m and V_max in this system were 24.5mm and 1.1 μmol · g⁻¹ · min⁻¹, respectively, representing a marked decrease in transport capability. Nevertheless, the degree of affinity in this extreme salinity must still be regarded as noteworthy. In addition to the high affinity transport system inD. hansenii, a low affinity system, presumably without relevance ind-glucosamine transport, was observed.     

Respiratory vasculatures of the intertidal air-breathing eel goby, <Emphasis Type="Italic">Odontamblyopus lacepedii</Emphasis> (Gobiidae: Amblyopinae)

Lacking a propensity to emerge over the mud surface, the eel goby, Odontamblyopus lacepedii, survives low tide periods by continuously breathing air in burrows filled with hypoxic water. As with most marine air-breathing fishes, O. lacepedii does not possess an accessory air-breathing organ, but holds air in the buccal–opercular cavity. The present study aimed to clarify how the respiratory vasculature has been modified in this facultative air-breathing fish. Results showed that the gills apparently lacked structural modifications for air breathing, whereas the inner epithelia of the opercula were richly vascularized. Comparison with two sympatric gobies revealed that the density of blood capillaries within 10μm from the inner opercular epithelial surface in O. lacepedii (14.5 ± 3.0 capillaries mm⁻¹; mean ± s.d., n = 3) was significantly higher than in the aquatic non-air-breathing Acanthogobius hasta (0.0 ± 0.0) but significantly lower than in the amphibious air-breathing mudskipper, Periophthalmus modestus (59.1 ± 8.5). The opercular capillary bed was supplied predominantly by the 1st efferent branchial arteries (EBA1) and drained by the opercular veins, which open into the anterior cardinal vein. Deep invaginations at the distal end of the EBA1 and the junction with EBA2 are suggestive of blood flow regulatory sites during breath-holding and apnoeic periods. It remains to be investigated how blood flow through the gills is maintained during breath holding when the buccal–opercular cavity is filled with air.     

Chemiluminescent in vitro estimation of the inhibitory constants of antioxidants ascorbic and uric acids in Fenton’s reaction in urine

The goal of this research was to measure in vitro the inhibitory constants of the antioxidants ascorbic and uric acid in urine, with lucigenin enhanced chemiluminescence (CL) in Fenton’s system. Maximum CL emission is registered in urine containing H₂O₂ (5·10⁻⁴ M), Fe²⁺ (5·10⁻⁵ M), EDTA (5·10⁻⁵ M), and chemical enhancer lucigenin (10⁻⁴ M) at pH 5.5 and 36°C. Ascorbic acid exhibits up to 4-fold stronger antioxidant effect than uric acid. The constants of antioxidant inhibition in urine were measured at concentrations 10⁻³ and 10⁻⁴ M: for ascorbic acid, 5.92 ± 0.04 and 24.05 ± 1.82 μmol·sec⁻¹; for uric acid, 1.60 ± 0.02 and 21.45 ± 0.97 μmol·sec⁻¹, respectively. Three phases of CL kinetics of urine are well observed: spontaneous CL (0–10 sec), fast flash of CL (10–50 sec), and latent period (50–300 sec). The antioxidant efficiency of ascorbic and uric acids in the final stage of catabolic processes in the body is discussed. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 8, pp. 1062–1065.     

Water-storage capacity ofThuja,Tsuga andAcer stems measured by dehydration isotherms

Water-storage capacity was measured inThuja occidentalis L.,Tsuga canadensis (L.) Carr., andAcer saccharum Marsh. during the dehydration of stem segments 1.5–2.5 cm in diameter. Stem water potential was measured with a temperature-corrected stem hygrometer and cavitations were detected acoustically. Water loss was measured by weight change. Dehydration isotherms consistently displayed three phases. The first phase, from water potential (Ψ) 0 to about −0.2 MPa, had a high capacitance (C>0.4kg water lost· (1 of tissue)⁻¹· MPa⁻¹) and we have attributed this high C to capillary water as defined by Zimmermann (1983, Xylem structure and the ascent of sap, Springer-Verlag). The second phase from Ψ=−0.5 to about −2.0 had the lowest C values (<0.02 kg·l⁻¹·MPa⁻¹) and was accompanied by a few cavitation events. This phase may have been a transition zone between capillary storage and water released by cavitation events as well as water drawn from living cells of the bark. The third phase also had a high C (about 0.07–0.22kg·l⁻¹·MPa⁻¹) and was associated with many cavitation events while Ψ declined below about −2.5 MPa; we presume the high capacitance was the consequence of water released by cavitation events. We discuss the ecological adaptive advantage of these three phases of water-storage in trees. In moist environments, water withdrawn from capillary storage may be an important fraction of transpiration, but may be of little adaptive advantage. For most of the growth season trees draw mainly on elastic storage, but stem elastic storage is less than leaf elastic storage and therefore unlikely to be important. In very dry environments, water relased by cavitation events might be important to the short-term survival of trees.     

Evidence for NO-dependent vasodilation in the trout (Oncorhynchus mykiss ) coronary system

The effects of l-arginine, and its analogues N ^ω-nitro-l-arginine methyl ester and N ^ω-nitro-l-arginine on vascular resistance were investigated in the intact coronary system of an isolated non-working trout heart preparation. l-Arginine, at 10^–8 mol · l^–1induced a slight vasodilatory effect (max 10%). N ^ω-nitro-l-arginine methyl ester and N ^ω-Nitro-l-arginine in the range 10^–8–10^–4 mol · l^–1 caused dose-dependent increases in coronary resistance. The vasodilatory action of l-arginine was abolished when the preparation was pretreated with 10^–4 mol · l^–1 N ^ω-nitro-l-arginine or N ^ω-nitro-l-arginine methyl ester. Nitroprusside alone at 1 mmol · l^–1 induced a maximum vasodilation (30%) of the coronary system. Methylene blue a known inhibitor of guanylate cyclase, induced a strong vasoconstriction (already significant at 10^–5 mol · l^–1) and was able to overcome the vasodilative effect of nitroprusside. The endothelial nitric oxide agonists acetylcholine and serotonin, established in mammalian vessels, also mediate vasodilation in trout coronary system. In 50% of preparations, acetylcholine induced a biphasic response with vasodilation at low concentration (max 15% at 10^–8 mol · l^–1). Serotonin displayed a dose-response vasodilation in the range 10^–8–10^–4 mol · l^–1 (max 20%). These vasodilative effects were reduced or abolished by 10^–4 mol · l^–1 l-NA. These data support the existence of NO-mediated vasodilation mechanisms in the trout coronary system. Accepted: 1 July 1996     

Exercise-induced hormone responses in girls at different stages of sexual maturation

The dependence of exercise-induced hormone responses on sexual maturation was tested in a 3-year longitudinal experiment on 34 girls (aged 11–12 years at the beginning). Sexual maturation was evaluated by Tanners five-stage scale. Children cycled for 20-min at 60% maximal oxygen uptake once a year. Cortisol, insulin, growth hormone, β-oestradiol, progesterone and testosterone concentrations in venous blood were determined by radioimmunoassay procedures. Basal concentrations of growth hormone increased and of cortisol decreased when breast stage III was reached. Reaching breast stage IV was associated with an increase in basal concentrations of β-oestradiol, progesterone and testosterone. The exercise induced significant increases in concentrations of cortisol, growth hormone and β-oestradiol and a decrease in insulin concentration. At breast stage III the increase in cortisol concentration was to a lower level [467 (SEM 42) vs 567 (SEM 46)nmol · l⁻¹] and growth hormone concentration to a higher level [29.4 (SEM 0.5) vs 12.8 (SEM 0.4)ng · ml⁻¹], while the fall in insulin concentration was less pronounced [postexercise level 10.6 (SEM 0.9) vs 7.8 (SEM 0.8)mU · l⁻¹] than in stage II. The magnitude of the cortisol response was reduced in the last stage of breast development (+42.1% vs +55.5% at stage II, +66.2% at stage III, and +50.0% at stage IV). The magnitude of β-oestradiol response was the lowest in breast stage IV (+15.8%) and the highest at stage V (+41.1%). The progesterone response became significant at stage IV and testosterone response at stage V. In conclusion, we found that reaching breast stage III was associated with altered responses of cortisol, insulin and growth hormone concentrations while the responses of the sex hormone concentrations became pronounced in the last stages of sexual maturation. Accepted: 17 September 1997     

Capillary supply and cross-sectional area of slow and fast twitch muscle fibres in man

Summary The muscles triceps brachii, quadriceps femoris (part vastus lateralis) and soleus were analysed in 6 men and 6 women for fibre composition (% slow twitch, ST-fibres and % fast twitch, FT-fibres), fibre cross sectional areas, and capillarization. Also the fraction of fibres enclosed by their own fibre type was analysed together with the capillary supply of these fibres. Fibre composition was 39(19–60)% ST in m. triceps brachii, 60(29–78)% ST in m. vastus lateralis and 73(49–88)% ST in m. soleus. Fibre areas ranged from 2,320 to 16,667 m² being smallest in m. triceps brachii and largest in m. soleus (p<0.05) and with ST fibres being significantly smaller than FT fibres in some of the muscles. In all muscles the shape of the fibres was elliptical with the larger diameter being about twice the smaller diameter. Capillary density per cross sectional muscle area was not related to the fibre composition and was 379(302–500) cap/mm² in m. triceps brachii, 404(284–529) cap/mm² in m. vastus lateralis and 417(333–592) cap/mm² in m. soleus. However, capillary supply expressed as fibre type area per capillary was up to 40% larger for FT-fibres than for ST-fibres within the same muscle (p<0.05). The capillary supply of enclosed fibres was not different from that of fibres surrounded also by the other fibre type. The results demonstrate that the difference in capillary supply to ST and FT-fibres is less distinct in humans than in other mammals, which is consistent with the metabolic potentials also being more alike.     

Comparative aspects of fibre types,areas, and capillary supply in the pectoralis muscle of some passerine birds with differing migratory behaviour

Summary Fibre types, fibre areas and capillary supply in the pectoralis muscle of fifteen passerines with four different patterns of migratory behaviour have been studied. The predominant fibre type was a fast-twitch oxidative-glycolytic which was the only fibre type present in all species, except in the robin and the blackbird where a fast fibre with intermediate oxidative capacity and a fast glycolytic fibre were also found. There was a significant difference in fibre areas between birds with different migratory strategies, with the long-distance migratory group having the smallest fibres. This also led to higher capillary densities, shorter diffusion distances and, consequently, more capillaries around the fibres relative to fibre area in this group. This indicates an adaptation in the morphology of the pectoralis muscle to differences in migration strategies. In the robin, the proportion of the intermediate fibre was significantly greater during the breeding season than during migration. Seasonal differences in fibre areas and capillary supply within a species were also seen, but no definite trends were detectable.Abbreviations CC capillary/fibre contacts - CCA mean number of capillaries in contact with a fibre relative to fibre cross-sectional area - MD mean diffusion length - CD capillary density - FG fast-twich glycolytic - FOG fast-twitch oxidative-glycolytic     

Localized agglutinin staining in muscle capillaries from normal and very old atrophic human muscle using winged bean (Psophocarpus tetragonolobus) lectin

 The winged bean (Psophocarpus tetragonolobus) agglutinin (total lectin) and its basic (WBA I) and acidic isoform (WBA II) were used to analyze capillaries in sections from human muscle. The microvessels were clearly labeled after incubation with the lectins in both normal muscle and in old muscles with age-related type II atrophy or muscle fiber grouping. Muscle fibers, nerves, and connective tissue remained unstained. The total lectin detected muscle capillaries from all blood group AB0 individuals. The isoform WBA I reacted only with blood vessels in blood group A and B individuals, while the blood vessels in blood group 0 individuals were demonstrated with WBA II. WBA I staining was inhibited by p-nitrophenyl α-galactopyranoside and N-acetylgalactosamine, whereas 2′-fucosyllactose and preincubation with an antibody against type-1 chain H abolished capillary staining with WBA II. The study demonstrates the usefulness of WBA as a marker of capillaries in human muscle. Accepted: 2 September 1996     

Routine oxygen consumption and characteristics of the myotomal muscle in tench: Effects of long-term acclimation to hypoxia

Summary Tench (Tinca tinca) were acclimated to either aerated (P _{O 2} 17.6 KPa) or hypoxic water (P _{O 2} 1.5 KPa) at 15° C. Fish acclimated to P _{O 2} 17.6 KPa had a routine oxygen consumption (mls O₂/Kg bodyweight/h) of 32.7 in aerated water. Upon acute exposure to P _{O 2} 1.5 KPa oxygen consumption decreased to 10.8 and 15.6 in fish acclimated to aerated and hypoxic water, respectively.On the basis of staining for glycogen and for the activities of myofibrillar ATPase and succinic dehydrogenase, three main fibre types can be differentiated in the myotomal muscle.Fibres have been classified as slow, fast aerobic and fast glycolytic. Fast aerobic fibres can be distinguished histochemically by their alkaline-stable Ca²⁺-activated myofibrillar ATPase activity and their intermediate levels of staining for glycogen and succinic dehydrogenase activity.The patterns of innervation of the fibre types have been investigated by staining neuromuscular endplates and peripheral axons for acetylcholinesterase activity. Motor axons to slow fibres branch extensively giving rise to a number of diffuse endplate formations on the same and adjacent fibres. Fast glycolytic fibres also have a complex pattern of innervation with 8–20 endplates per fibre. A large proportion of the endplates belonged to separate axons.Cross-sectional areas and perimeters of fibres, the number of capillaries/fibre and the lengths of contacts between capillaries and fibres were determined from low-magnification electron micrographs.Acclimation to hypoxia resulted in a decrease in the number of capillaries per fibre for both slow (1.8 to 1.0) and fast (0.8 to 0.2) muscles. The capillary perimeter supplying 1 m² of fibre cross-sectional area decreased by 43 % and 76 % for slow and fast fibres, respectively.     

Ecophysiological studies on citrate-synthase: (I) enzyme regulation of selected crustaceans with regard to temperature adaptation

The characteristics and properties chromatographically purified citrate synthase from the euphausiids Euphausia superba (Antarctica) and Meganyctiphanes norvegica (Scandinavian Kattegat and Mediterranean Sea) and from the isopods Serolis polita (Antarctica) and Idotea baltica (Baltic Sea) were used to elucidate biochemical mechanisms of temperature adaptation. Additionally, maintenance experiments were carried out on the euphausiids to determine mechanisms of short term acclimation. Temperature optima (between 37 and 45°C) were unrelated to genotypic cold adaptation, but the activation energy of the Antarctic krill E. superba (10.9 kJ · mol^-1) was only a quarter of that in other species (41.8–45.1 kJ · mol^-1). The minima of apparent Michaelis constants (total range: 4–20 μmol · 1^-1 oxaloacetate; 7–45 μmol · 1^-1 acetyl-coenzyme A) showed no relation to natural conditions, and no distinct pH optimum occurred at ambient temperatures. In contrast, apparent Michaelis constants and specific enzyme activities were related to maintenance temperatures in M. norvegica, but not in E. superba. The differences between M. norvegica and E. superba can be interpreted as adaptations to the changes in ambient temperature with regard to the respective steno- and eurythermic tolerances of these crustaceans.     

Synaptic inhibition of smooth muscles of the human colon: Effects of vitamin B6 and its derivatives

Spontaneous activity, which is manifested as slow depolarization waves and action potentials, is observed in most (81%) smooth muscles (SMs) of the circular layer of the human colon. Independently of the type of pathology, inhibitory junction potentials (IJPs) in SMs of various parts of the human colon are evoked by intramural stimulation; ranges of parameters of these potentials were comparable with those observed in muscle intestinal fragments isolated at a distance of several tens of centimeters from the zone of injury. In muscle strips (MSs) of such fragments, pyridoxal-5′-phosphate (PPh) applied in different concentrations caused suppression of IJPs: in the concentration of 1·10⁻⁸ to 1·10⁻⁴ M it decreased the amplitude, and in the concentrations of 1·10⁻⁵ to 1·10⁻⁴ M and 1·10⁻⁴ M, respectively, it decreased rates of the half-amplitude rise and decay of these potentials. Pyridoxal (1·10⁻⁴ M) and 4-pyridoxolic acid (1·10⁻⁴ M) also caused a drop in the amplitude of IJPs; however, these agents influenced this parameter to a lesser extent, as compared with the effect of 1·10⁻⁴ M PPh. Pyridoxine (1·10⁻⁴ M) and pyridoxamine (1·10⁻⁴ M) evoked no significant changes in the parameters of IJPs in MSs of the human colon. Our data allow us to hypothesize that the suppressing effect of PPh on IJPs is determined by the presence of a purinergic component present in non-adrenergic inhibition of SMs of the human colon. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 269–279, July–August, 2006.     

New ribosome-inactivating proteins with polynucleotide:adenosine glycosidase and antiviral activities from Basella rubra L. and Bougainvillea spectabilis Willd.

New single-chain (type 1) ribosome-inactivating proteins (RIPs) were isolated from the seeds of Basella rubra L. (two proteins) and from the leaves of Bougainvillea spectabilis Willd. (one protein). These RIPs inhibit protein synthesis both in a cell-free system, with an IC₅₀ (concentration causing 50% inhibition) in the 10⁻¹⁰ M range, and by various cell lines, with IC₅₀s in the 10⁻⁸–10⁻⁶ M range. All three RIPs released adenine not only from rat liver ribosomes but also from Escherichia coli rRNA, polyadenylic acid, herring sperm DNA, and artichoke mottled crinkle virus (AMCV) genomic RNA, thus being polynucleotide:adenosine glycosidases. The proteins from Basella rubra had toxicity to mice similar to that of most type 1 RIPs (Barbieri et al., 1993, Biochim Biophys Acta 1154: 237–282) with an LD₅₀ (concentration that is 50% lethal) ≤ 8 mg · kg⁻¹ body weight, whilst the RIP from Bougainvillea spectabilis had an LD₅₀ >32 mg · kg⁻¹. The N-terminal sequence of the two RIPs from Basella rubra had 80–93% identity, whereas it differed from the sequence of the RIP from Bougainvillea spectabilis. When tested with antibodies against various RIPs, the RIPs from Basella gave some cross-reactivity with sera against dianthin 32, and weak cross-reactivity with momordin I and momorcochin-S, whilst the RIP from Bougainvillea did not cross-react with any antiserum tested. An RIP from Basella rubra and one from Bougainvillea spectabilis were tested for antiviral activity, and both inhibited infection of Nicotiana benthamiana by AMCV. Received: 5 March 1997 / Accepted: 27 May 1997     

Phenotypic differences between red pulp capillary and sinusoidal endothelia help localizing the open splenic circulation in humans

The distribution of capillaries, sinuses and larger vessels was investigated by immunohistology in paraffin sections of 12 adult human spleens using a panel of antibodies. Double staining for CD34 and CD141 (thrombomodulin) revealed that capillary endothelia in the cords of the splenic red pulp and at the surface of follicles were CD34⁺CD141⁻, while red pulp sinus endothelia had the phenotype CD34⁻CD141⁺. Only in the direct vicinity of splenic follicles did sinus endothelial cells exhibit both antigens. Thus, splenic sinuses do not replace conventional capillaries, but exist in addition to such vessels. The endothelium in arterioles, venules and larger arteries and veins was uniformly CD34⁺CD141⁺. Anti-CD34 and anti-CD141 both additionally reacted with different types of splenic stromal cells. Differential staining of capillaries and sinuses may permit a three-dimensional reconstruction of serial sections to unequivocally delineate the “open” and “closed” splenic circulation in humans.     

Lymphatic vessels in lungfishes (Dipnoi)

 Lymphatic capillaries are distributed throughout the body of lepidosirenid and protopterid Dipnoi, except in the central nervous system. They form small, interconnected units which are individually evacuated into nearby blood capillaries by lymphatic micropumps. The number of lymphatic micropumps varies considerably in different parts of the body. In fin areas, 30–50 per mm³ tissue may be considered normal in Protopterus annectens, but up to 105 per mm³ have been counted in an anterior fin of Lepidosiren paradoxa. Lymphatic capillaries are formed by thin endothelial cells with fine processes into the surrounding interstitial space. Occasionally there is a faint, discontinuous basal lamina. Pericytes, however, are completely absent. Microfibrils establish contact between endothelial cells and surrounding connective tissue fibers. The lymphatic micropumps are essentially spherical, contractile organs of 35–55 μm in diameter. Their central lumen is lined by extensions of a single endothelial cell. Additional endothelial cells form inflow and outflow valves. The endothelial layer is surrounded by a single large, highly specialized muscle cell. This spherical muscle cell has many perforations, allowing the passage of thin outward processes of the endothelial cell which form part of the suspension apparatus of the lymphatic micropump. The muscle cell establishes a specialized end-to-end contact between opposing parts of its own cell membrane. This contact is very similar to an intercalated disc in vertebrate heart muscle. Each lymphatic micropump is suspended within a cell-free tissue area by microfibrils which radiate from the lymphatic micropump into the surrounding connective tissue. The microfibrils are occasionally reinforced by single collagen fibers. The cell-free area around each lymphatic micropump appears as a bright halo in both light and electron micrographs. No type of lymphatic vessel other than lymphatic capillaries could be detected in the Dipnoi studied. Lepidosireniform Dipnoi are the only Vertebrata besides the Tetrapoda in which lymphatic vessels and characteristic lymphatic pumps have been documented. In addition, these Dipnoi and all Tetrapoda share the same overall design of blood circulation, which is not divided into a primary and a secondary system of vessels, as it is in Actinopterygii, Chondrichthyes, and Agnatha. Since there are primary and secondary blood vessels in the gills of Latimeria chalumnae, while the existence of lymphatic vessels has not been confirmed, general angioarchitecture should be taken into account as an important character when phylogenetic relationships among extant Sarcopterygii are discussed. Accepted: 7 October 1997     

Role of VA-mycorrhiza in growth and mineral nutrition of apple (Malus pumila var.domestica) rootstock cuttings

One-year-old apple cuttings (Malus pumila var.domestica cv. M26) were grown for 6 months in pot culture with and without inoculum of the VA-mycorrhizal fungus (VAMF)Glomus macrocarpum in soil from a long-term fertilizer field experiment with different P availability (20, 210, and 280 mg CAL-extractable P kg⁻¹). The indigenous VAMF propagule density was reduced by 0.5 Mrad X-irradiation. At harvest, non-inoculated and inoculated plants had similar proportions of root length bearing vesicles. Net dry weight of tree cuttings was significantly increased by inoculation only at 20 mg P kg⁻¹ (+62%). Increasing P availability from 210 to 280 mg P kg⁻¹ led to a 4-week depression of shoot elongation rate only in the inoculated plants. Uptake of P was significantly enhanced by inoculation at 20 and 210 mg P kg⁻¹ (+64 and +12%, respectively). On average, inoculated plants had significantly higher concentrations of Zn in leaves and in roots (+16 and +14%, respectively) and of copper in stems and in roots (+13 and +126%, respectively). Proportion of vesicle bearing root length was significantly correlated with root caloric content. A lipid content of 0.9–4.5% in the root dry matter was attributed to the presence of vesicles corresponding to 1.6–8.2% of total root caloric content. As the control plants were also infected, the beneficial effect of VA-mycorrhiza on nutrient uptake and growth of apple cuttings was underestimated at all P levels. Furthermore, VAM-potential at the lowest P level was not fully exploited as onset of infection was most certainly delayed because of a decreased photosynthetic rate due to P deficiency. Energy drain by VAMF-infection was most probably underestimated considerably, due to, among others, loss of infected root cortex during root growth, sampling and staining. It is concluded that apple cuttings rely on VA-mycorrhizal P-uptake at least in low P soils. In high P soils, apple cuttings may profit predominantly from the uptake of Zn and Cu by the fungal symbionts.     

Cervical mucins carry α(1,2)fucosylated glycans that partly protect from experimental vaginal candidiasis

Cervical mucins are glycosylated proteins that form a protective cervical mucus. To understand the role of mucin glycans in Candida albicans infection, oligosaccharides from mouse cervical mucins were analyzed by liquid chromatography-mass spectrometry. Cervical mucins carry multiple α(1-2)fucosylated glycans, but α(1,2)fucosyltransferase Fut2-null mice are devoid of these epitopes. Epithelial cells in vaginal lavages from Fut2-null mice lacked Ulex europaeus agglutinin-1 (UEA-I) staining for α(1-2)fucosylated glycans. Hysterectomy to remove cervical mucus eliminated UEA-I and acid mucin staining in vaginal epithelial cells from wild type mice indicating the cervix as the source of UEA-I positive epithelial cells. To assess binding of α(1-2) fucosylated glycans on C. albicans infection, an in vitro adhesion assay was performed with vaginal epithelial cells from wild type and Fut2-null mice. Vaginal epithelial cells from Fut2-null mice were found to bind increased numbers of C. albicans compared to vaginal epithelial cells obtained from wild type mice. Hysterectomy lessened the difference between Fut2-null and wild type mice in binding of C. ablicans in vitro and susceptibility to experimental C. albicans vaginitis in vivo. We generated a recombinant fucosylated MUC1 glycanpolymer to test whether the relative protection of wild type mice compared to Fut2-null mice could be mimicked with exogenous mucin. While a small portion of the recombinant MUC1 epitopes displayed α(1-2)fucosylated glycans, the predominant epitopes were sialylated due to endogenous sialyltransferases in the cultured cells. Intravaginal instillation of recombinant MUC1 glycanpolymer partially reduced experimental yeast vaginitis suggesting that a large glycanpolymer, with different glycan epitopes, may affect fungal burden.