A histofluorescence study of events accompanying accumulation and migration of norepinephrine within locally cooled nerves.

Glyoxylic acid was used to induce fluorescence in sections of rabbit sciatic nerve. In fresh nerves treated with this agent there were scattered finely beaded axons with a weak blue-green fluorescence. During local cooling, blue-green fluorescence accumulated steadily at the proximal boundary of the cooled region but never at its distal boundary. This accumulation gave rise to dilated axons that often swelled into brilliantly fluorescent balloon-like structures up to 10 microgram in diameter. Axonal fluorescence was probably specific for norepinephrine, being enhanced by inhibition of the metabolism and diminished by inhibition of the synthesis or storage of this neurotransmitter. After local cooling of nerves for 1.5 hr, specific fluorescence was confined within 0.8 mm of the cooled region. Rewarming led to rapid removal of fluorescence from the cooled region and to disappearance of most of the balloon-like swellings. Simultaneously, rewarming caused brightly fluorescent fibers that were neither dilated nor swollen to appear in distal regions of nerve. As this wave of fluorescence migrated distally with increasing duration of rewarming, it was spread over increasingly broad regions of nerve, which suggests that axonal transport of norepinephrine may invole some kind of dispersive process.     

A comparative study of asymmetric migration events across a marine biogeographic boundary

In many nonclonal, benthic marine species, geographic distribution is mediated by the dispersal of their larvae. The dispersal and recruitment of marine larvae may be limited by temperature gradients that can affect mortality or by ocean currents that can directly affect the movements of pelagic larvae. We focus on Point Conception, a well-known biogeographic boundary between the Californian and Oregonian biogeographic provinces, to investigate whether ocean currents affect patterns of gene flow in intertidal marine invertebrates. The predominance of pelagically dispersing species with northern range limits at Point Conception suggests that ocean currents can affect species distributions by erecting barriers to the dispersal of planktonic larvae. In this paper, we investigate whether the predominantly southward currents have left a recognizable genetic signature in species with pelagically dispersing larvae whose ranges span Point Conception. We use patterns of genetic diversity and a new method for inferring cladistic migration events to test the hypothesis that southward currents increase southward gene flow for species with pelagically dispersing larvae. We collected mitochondrial DNA (mtDNA) sequence data for the barnacles Balanus glandula and Chthamalus fissus and also reanalyzed a previously published mtDNA dataset (Strongylocentrotus purpuratus, Edmands et al. 1996). For all three species, our cladistic approach identified an excess of southward migration events across Point Conception. In data from a fourth species with nondispersing larvae (Nucella emarginata, Marko 1998), our method suggests that ocean currents have not played a role in generating genetic structure.     

Immunocytochemical demonstration of nerve growth factor and histofluorescence of catecholaminergic nerves in the salivary glands of diabetic mice

Summary Nerve growth factor (NGF) was localized in the submandibular, sublingual, and parotid salivary glands of male and female diabetic mice and their normal littermates by immunoperoxidase staining usingp-phenylenediamine-pyrocatechol as a chromogen for the cytochemical demonstration of peroxidase activity. In the normal male submandibular gland, immunoreactive NGF was localized in the apical regions of granular, intercalated and collecting duct cells, while in the normal female submandibular gland, NGF was present throughout the cytoplasm of granular duct cells. The localization of NGF in the diabetic male and female submandibular glands was similar and resembled that of the normal female. NGF immunoreactivity was also observed in the striated duct cells in the sublingual and parotid glands of all four types of mice.The sympathetic innervation of the submandibular glands of normal and diabetic mice was demonstrated using glyoxylic acid-induced histofluorescence. The pattern of sympathetic innervation and the intensity of catecholamine fluorescence was consistently different in the four types of mice. In the normal male submandibular gland the fluorescence was very intense, particularly in nerves adjacent to the granular ducts. In the normal female submandibular gland, the fluorescence was weak, while in the diabetic male and female the fluorescence was moderate.The correlation between the intensity of the immunocytochemical staining for NGF and the catecholamine fluorescence adjacent to the granular ducts suggests a trophic influence of the NGF-containing granular ducts on their sympathetic innervation.     

Feeding increases 5-hydroxytryptamine and norepinephrine within the hypothalamus of chicks

It is thought that hypothalamic 5-hydroxytryptamine (5HT) and norepinephrine (NE) are involved in the regulation of feeding in chicks. The present study was conducted to elucidate changes in the levels of extracellular 5HT and NE in the hypothalamus during feeding of chicks. In order to measure 5HT, NE and 4-hydroxy-3-methoxyphenylglycol (MHPG), which is a major metabolite of NE, we used brain microdialysis and high-pressure liquid chromatography with an electrochemical detector. After collecting samples to determine the basal levels of 5HT, NE and MHPG, food-deprived birds were given access to food. 5HT levels in the medial hypothalamus (MH) and lateral hypothalamus (LH) increased during the first 30 min of feeding, and then returned to basal levels. NE and MHPG in the LH increased during feeding, and remained elevated throughout the experiment. This study supports an idea that hypothalamic monoamines in the chick brain are involved in the regulation of feeding.     

Localization of noradrenaline and serotonin in nerves in the pineal gland of rats and guinea-pigs studied by glyoxylic acid histofluorescence and electron microscopy

Summary The nerves in the pineal gland of the rat and guinea-pig contain both noradrenaline and serotonin and fluoresce intensely after histofluorescence procedures. Vesicle-filled terminals in the perivascular space of the pineal body contain numerous clear and dense-cored vesicles. A 5mg/kg dose of reserpine causes disappearance of histofluorescence from the pineal nerves and a virtual elimination of dense-cored vesicles from vesicle-filled terminals. A 1mg/kg dose of reserpine results in loss of fluorescence and virtual depletion of dense cores in nerves in the rat, but the guinea-pig pineal nerves continue to fluoresce lightly and the dense-cored vesicles are still present but reduced to about 1/3 in number. Subsequent treatment of lightly reserpinized guinea-pigs withp-chlorophenylalanine, a specific depletor of serotonin, results in dis ppearance of fluorescence in nerves in the pineal gland and virtual depletion of the remaining dense cores. A dose of 1mg/kg reserpine succeeds in depleting noradrenaline from most peripheral nervous structures of the guinea-pig. Hence, the remaining monoamine in guinea-pig pineal nerves after depletion of noradrenaline appears to be serotonin located in the remaining dense-cored vesicles. Since, in lightly reserpinized guinea-pig pineal nerves, a number of dense-cored vesicles containing serotonin are still present after depletion of noradrenaline, it is suggested that noradrenaline and serotonin are not in the same vesicles at the same time.     

A tracer study with systemically and locally administered dinitrophenylated osteopontin.

Osteopontin (OPN), a major non-collagenous matrix protein of bone, is also found in tissue fluids and in the circulation. It is still not clear whether circulating OPN contributes to bone formation. To elucidate this question, rat OPN was tagged with dinitrophenol groups and administered to rats either intravenously or by infusion with an osmotic minipump through a "surgical window" in the bone of the hemimandible. Dinitrophenylated rat albumin (ALB) was used as a control. The presence and distribution of tagged proteins were revealed by immunogold labeling on sections of tibia and alveolar bone. Tagged molecules of OPN were found in mineralization foci, surfaces and interfaces, and matrix accumulations among calcified collagen fibrils. Even though dinitrophenylated ALB was administered at several-fold higher concentrations, it did not accumulate in these sites. These results show that circulating OPN can be incorporated into specific compartments of forming bone and suggest that such molecules may play a more important role than previously suspected.     

Uptake and accumulation in vitro of 3H-noradrenaline in adrenergic nerves of human atrium

Summary The adrenergic innervation and the in vitro uptake of ³H-noradrenaline has been investigated in human atrial tissue slices from patients undergoing thoracic surgery. The atrial appendage was richly innervated, but the density of the adrenergic nerve plexus varied considerably between different tissues examined. The nerve terminals were of characteristic varicose appearance, running singly or in bundles along the long axis of the muscle fibers. The nerve fibers seemed to penetrate in between the muscle cells. The distribution and appearance of the adrenergic nerves were quite similar to those described in earlier investigations of heart tissue from other species. The uptake and accumulation of ³H-noradrenaline in vitro increased with increasing concentration in the medium and with time, and the uptake process could efficiently be blocked by desmethylimipramine (DMI), a potent inhibitor of the uptake mechanism located at the axonal membrane, the so called membrane pump. There was a true accumulation of ³H-noradrenaline in the atrial tissue during the incubation, compared to the medium. The metabolism of ³H-noradrenaline during the incubation has also been studied. The data presented speak in favour of the view that the adrenergic nerves of human atria possess an efficient uptake accumulation mechanism for noradrenaline.Abbreviations used DMI desmethylimipramine - NA noradrenaline - NM normetanephrine     

各种改性剂对重金属迁移,积累影响的研究

采用盆栽实验．研究了在不同改性措施条件下,Ｃｄ、Ｐｈ、Ｃｕ、Ｚｎ、Ａｓ多元素复合污染物对水稻、大豆生长的影响及重金属在土壤－作物系统中迁移、积累的特性．结果表明,作物根系中的离子冲量越大,对作物危害越重．酸处理对作物生长影响较大,而腐殖酸和石灰处理有利于作物的生长．改性剂对重金属迁移能力影响大小依次为酸＞腐殖酸＞石灰．作物的不同部位对重金属吸收的顺序为根＞茎叶＞籽实．重金属在土壤－作物系统中的迁移能力为Ｃｄ＞Ｚｎ＞Ｃｕ＞Ａｓ＞Ｐｂ．     

Distribution and diel migration of macroinvertebrates within dense submerged vegetation

1. We studied vertical and horizontal distribution of macroinvertebrates within a dense stand of Chara spp. in Lake Krankesjön, southern Sweden. Invertebrates were sampled at three depths within the vegetation and at three distances from the vegetation edge during day and night in July and August. Corresponding samples of oxygen content of the water were taken.
2. The densities (number of invertebrates per unit plant biomass) of most invertebrate taxa were generally lower in the upper layers of the vegetation than in the layers close to the sediment. The densities of several taxa ( Asellus aquaticus , Cloëon sp. and Polycentropodidae), as well as total density of invertebrates, were higher at the edge than in the innermost parts of the macrophyte stand, whereas snail densities generally were highest at the innermost sites.
3. Densities of A. aquaticus , Chironomidae larvae and Helobdella stagnalis generally increased at night. These taxa appear to undertake a diel vertical migration within the vegetation, towards, or even down to the sediment in daytime and up into the vegetation, in some cases to the vegetation surface, at night. Factors underlying the diel vertical migration are discussed, as are their ecological consequences.     

A comparative study of oculomotor,trochlear and abducens nerves in Arabian foals

We investigated the microscopic structure of transverse sections of the oculomotor, trochlear and abducens nerves of Arabian foals using stereological methods. Bilateral nerve pairs from 2-month-old female Arabian foals were analyzed. The tissues were embedded in plastic blocks, then 1 µm thick sections were cut and stained with osmium tetroxide and methylene blue-azure II. Stereology was performed using light microscopy. Morphometry showed that the right and left pairs of nerves were similar. The transverse sectional areas of the oculomotor, trochlear and abducens nerves were 1.93 ± 0.19 mm², 0.32 ± 0.06 mm² and 0.70 ± 0.08 mm², respectively. The oculomotor nerve exhibited a significantly greater number of myelinated axons (16755 ± 1279) and trochlear (2656 ± 494) and the abducens nerves (4468 ± 447). The ratio of the axon diameter to myelinated nerve fiber diameter was 0.58, 0.55 and 0.55 for the oculomotor, trochlear and abducens nerves, respectively. Of the three nerves studied, the abducens nerve exhibited the greatest nerve fiber area, myelin area, nerve and axon diameters, and myelin thickness. The ratio of small myelinated nerve fibers was greatest in the oculomotor nerve.     

A spin-label study of sciatic nerves from quaking,jimpy and trembler mice

The spin labels, 5-nitroxide stearic acid and 16-nitroxide stearic acid were incorporated into whole sciatic nerves dissected from normal, quaking, jimpy and trembler mice. With 5-nitroxide stearic acid, we have studied the thermal variation of the maximal apparent coupling constant ($\text{T}{}_6$) between 0°C and 50°C. Within this range of temperatures, we obtained identical values of 2 $\text{T}{}_6$ for nerves from normal and jimpy mice, whereas 2 $\text{T}{}_6$ was smaller for nerves from quaking and trembler mice. With 16-nitroxide stearic acid, composite spectra were recorded, particularly in the high-field range. A line characteristic of myelin was clearly observed in the spectra of nerves from normal and jimpy mice; its intensity was somewhat less in nerves from quaking mice and much less in spectra from trembler mice. A shoulder in the principal highfield line of the spectrum is modified only with nerves from jimpy mice.The results agree well with those obtained by electron microscopy, which reveal normal myelination in nerves from jimpy mice, a slight modification of the myelin from those of quaking mice and a practically complete demyelination in peripheral nerves from trembler mice. However, the structure of the nerves of jimpy mice also seems to be modified at an, as yet, undetermined level.     

Oxygen distribution and migration within Mbdes Fe and Hbdes Fe. Multifrequency phase and modulation fluorometry study.

Quenching of the intensity and lifetime of porphyrin fluorescence from Mbdes Fe and Hbdes Fe (iron-free myoglobin and hemoglobin) by oxygen was investigated using a multifrequency cross-correlation phase fluorometer. The single exponential decay characteristic of porphyrin emission of Mbdes Fe and Hbdes Fe became doubly exponential upon application of oxygen pressure. The results were interpreted in terms of a general model of dynamic quenching of fluorescence in globular proteins. The model accounted for the rate k+ of acquisition of quencher by the protein, the exit rate k- of quencher from the protein, and the migration rate chi of quencher in the protein interior. The values of k+, k-, and chi were different for Mbdes Fe and Hbdes Fe. The addition of 40% sucrose, which increased the bulk viscosity sixfold, modified these rates. These results are discussed and compared with previous quenching studies on proteins. The significance of these results and the model for the interpretation of protein quenching studies is emphasized.     

Putative causes and consequences of MHC variation within and between locally adapted stickleback demes

Genes of the major histocompatibility complex (MHC) have been a source of considerable research interest, owing in large part to the growing body of evidence that they may be subject to both natural and sexual selection. However, much remains to be learned about the dynamics of MHC genes in subdivided populations, particularly those characterized by divergent ecological pressures. In this study, we attempt to disentangle the relative roles of both parasite-mediated selection and MHC-mediated mate choice in an open estuarine system inhabited by two parapatric, adaptively divergent threespine stickleback (Gasterosteus aculeatus) demes. We sequenced the putative peptide-binding region (PBR) of an estimated four Class IIβ loci from 127 individuals, identifying 329 sequence variants (276 translated amino acid sequences). Demes differed significantly both in the frequency of MHC alleles and in the communities of helminth parasites infecting resident sticklebacks. Strong signatures of natural selection were inferred from analyses of codon substitutions, particularly in the derived (freshwater) rather than the ancestral (marine) deme. Relationships between parasite load and MHC diversity were indicative of balancing selection, but only within the freshwater deme. Signals of MHC-mediated mate choice were weak and differed significantly between demes. Moreover, MHC-mediated mate choice was significantly influenced by environmental salinity and appeared of secondary importance to tendencies towards assortative mating. We discuss the implications of these findings in respect to ecological adaptation and the potential demographic consequences of possible outcomes of MHC-mediated mate choice.