Phlorizin inhibits hexose transport across the plasmalemma of Riccia fluitans

The effect of phlorizin has been tested on hexose transport and hexose-induced changes of electrical potential (_m) and conductance (g _m) across the plasmalemma of rhizoid and thallus cells of the aquatic liverwort Riccia fluitans. The decrease of _m (depolarization) and g _m induced by 1 mM 3-oxymethyl-D-glucose (3-OMG) is substantially inhibited by simultaneous addition of 2 mM phlorizin, whereas no significant response was observed when phlorizin was added alone or several minutes after the sugar. Current-voltage data show that the 3-OMG-generated electrical inward current of 0.016 A m^-2 drops to 0.010 A m^-2 when phlorizin is present. Uptake as well as efflux of [¹⁴C]-3-OMG is strongly and reversibly inhibited by phlorizin between 0.2 and 5 mM. The results are consistent with our hypothesis that the hexose carrier has one binding site with competitive inhibition of glucose uptake by phlorizin (k _i=0.08 mM). The electrical data indicate that phlorizin affects an _m step of the carrier transport cycle.Abbreviation 3-OMG 3-oxymethyl-D-glucose     

Neurosekretartige Grana in den peripheren Nerven und in den Nerv-Muskel-Verbindungen von Helix pomatia

Zusammenfassung Der glatte Penisretraktormuskel von Helix pomatia enthält wenigstens drei, vielleicht vier verschiedene Arten von Nervenfasern. Sie lassen sich an der Struktur ihrer neurosekretartigen Grana voneinander unterscheiden. In Fasern aus dem Herzen von Helix wurde noch ein weiterer Granatyp gefunden. Er ähnelt den bisher bekannten synaptischen Vesiculi der Vertebraten und Arthropoden. Im glatten Penisretraktor treten mindestens zwei verschiedene Arten von Nervenfasern in engen Kontakt mit den Muskelfasern. Hierbei buchtet sich die Oberfläche der Muskelfaser unter Umständen tief ein. Verschiedenartige Nervenfasern können unmittelbar nebeneinander die Muskelfaser berühren, müssen es aber nicht.Umgekehrt können sich auch mehrere Muskelfasern eng um eine einzige Nervenfaser gruppieren. An den Enden der Neuriten ist die Granakonzentration besonders groß. Gruppen von Nervenfasern oder auch einzelne Fasern sind locker von Gliazellen umsponnen. Hierbei bleiben stets weite Bereiche der Axon-membran frei, die dann über eine dünne zwischengeschaltete Basalmembran unmittelbar an das interstitielle Bindegewebe grenzen. Charakteristisch für die Gliazellen sind etwa 0,5 große, von dichter homogener Masse erfüllte membranbegrenzte Grana. In der Nähe von Nervenendigungen sind sie besonders zahlreich.Das Sarkoplasmatische Reticulum setzt sich aus zwei Komponenten zusammen: erstens einem peripheren tubulären System, das sich von der Sarkolemm-membran abfaltet. Seine Membran besitzt dieselbe Dicke wie die Sarkolemm-membran. Zweitens einem vornehmlich peripher, aber auch zentral anzutreffendem vesiculärem System. Es faltet sich von der äußeren Kernmembran ab; seine Membran ist wesentlich dünner.Außerdem stößt man an der Peripherie und im Zentrum dieser Muskelfasern relativ häufig auf Bündel von eng beieinanderliegenden Röhrchen (Länge etwa 1 ); sie verlaufen gewöhnlich parallel zu den Myofilamenten.Die Arbeit wurde durchgeführt mit Unterstützung durch die Deutsche Forschungs-gemeinschaft.     

Occurrence of eelAnguilla anguilla larvae west of the European continental shelf, 1971–1977

Synopsis Seven hundred and thirty seven eel larvae were caught in 1971 and in the period 1973–1977 by a modified Isaacs Kidd Midwater Trawl off and on the continental shelf west of France and the British Isles. According to Schmidt (1909) no larvae have been caught on the shelf itself except one glass eel. A decrease in number as well as a decrease of older stages from east to west was observed. Besides the maximum in the length frequency distribution some more smaller peaks occurred. No essential size differences existed between 1975 and 1977, between younger and older developmental stages and between northern and southern larvae. Depth preference during daylight was 300–600 m, at night 35–125 m. Mean density of larvae in the preferred depth layers was nearly 1 per 1000 m³. High densities alternated from year to year with low densities which corresponded to the total catch fluctuations of the elver ascent in the River Ems at Herbrum (West Germany) in the following spring. The possible relationships in mortality between the metamorphosing leptocephalus and immigrating elvers and between the emigrating silver eels and the metamorphosing leptocephalus are discussed.     

Molecular evolution and mosaicism of leptospiral outer membrane proteins involves horizontal DNA transfer

Leptospires belong to a genus of parasitic bacterial spirochetes that have adapted to a broad range of mammalian hosts. Mechanisms of leptospiral molecular evolution were explored by sequence analysis of four genes shared by 38 strains belonging to the core group of pathogenic Leptospira species: L. interrogans, L. kirschneri, L. noguchii, L. borgpetersenii, L. santarosai, and L. weilii. The 16S rRNA and lipL32 genes were highly conserved, and the lipL41 and ompL1 genes were significantly more variable. Synonymous substitutions are distributed throughout the ompL1 gene, whereas nonsynonymous substitutions are clustered in four variable regions encoding surface loops. While phylogenetic trees for the 16S, lipL32, and lipL41 genes were relatively stable, 8 of 38 (20%) ompL1 sequences had mosaic compositions consistent with horizontal transfer of DNA between related bacterial species. A novel Bayesian multiple change point model was used to identify the most likely sites of recombination and to determine the phylogenetic relatedness of the segments of the mosaic ompL1 genes. Segments of the mosaic ompL1 genes encoding two of the surface-exposed loops were likely acquired by horizontal transfer from a peregrine allele of unknown ancestry. Identification of the most likely sites of recombination with the Bayesian multiple change point model, an approach which has not previously been applied to prokaryotic gene sequence analysis, serves as a model for future studies of recombination in molecular evolution of genes.     

Retention of differentiated characteristics in human fetal keratinocytes in vitro

Summary Many of the morphologic and biochemical changes that occur during human fetal skin development have been described, yet there has been little experimental analysis of the processes that regulate the development of human fetal skin. This is due in part to difficulties in culturing human fetal epidermal keratinocytes. We have successfully cultured fetal keratinocytes in two different in vitro systems; in a serum-free keratinocyte growth medium (KGM) on tissue culture plastic and cocultured with dermal fibroblasts as spheroidal aggregates. To characterize these fetal keratinocytes in vitro we have assessed their ability to express several markers of epidermal differentiation. Human fetal keratinocytes grown on plastic in KGM stratify and express some of the components of the differentiated epidermis, such as involucrin and the high molecular weight keratins. However, these keratinocytes co-express keratins and vimentin and do not form a structured basement membrane. More characteristics of fetal skin are preserved in mixed aggregates of epidermal keratinocytes and dermal fibroblasts including epidermal stratification, synthesis of basement membrane components, tissue-specific expression of intermediate filaments, involucrin, and expression of high molecular weight keratins. The maintenance of human fetal epidermal keratinocytes in these two in vitro systems and their ability to express many differentiated characteristics suggests that these cultures will be valuable for studies of the molecular mechanisms that regulate the regionally specific differentiation of the human fetal epidermis. This work was supported by the Dermatology Foundation Fellowships funded by Herbert Laboratories and The Upjohn Company and awarded to A. R. H., NIH Training Program in Dermatological Research #5T32AR07472, and NIH grant #5R01HD20996 to A. T. L. Publication no. 74 of the Dermatology Department, University of Rochester, Rochester, NY.     

Prothoracic DUM neurons of the cricket Gryllus bimaculatus — responses to natural stimuli and activity in walking behavior

Summary Responses to sensory stimuli and spike activity uring walking were investigated in bilaterally symmetrical dorsal unpaired median (DUM) neurons of the cricket. Intracellular recordings within the prothoracic ganglion were made either in restrained animals or in stationary walking specimens whilst parameters of their intended locomotion were measured. Three types of DUM cells were distinguished morphologically and physiologically. DUMa neurons send axons through segmental nerves. They often generated spontaneously large action potentials with low frequencies. Most DUMa neurons showed multimodal sensitivity, preferentially to cereal wind puffs and 15 kHz sound. Mean latencies ranged from 25 to 349 ms. Their large intraindividual variability could be correlated with behavioral modes during walking. Generally, the spike frequency increased with increased forward speed, while it was not related to turning. DUMb neurons projected either through the anterior or posterior connectives, but seemed physiologically similar to DUMa neurons. DUMc neurons were H-shaped with axons in both pairs of connectives. No external stimulus led to discrete spikes, but the regular spontaneous activity was modulated following cereal wind puffs to a restrained animal. During wind evoked escape the spike activity of another DUMc cell was modulated in phase with the rhythmic running behavior. The possibly different functions of DUMa and DUMc neurons during walking are discussed.     

Neonatal phenobarbital imprinting of rat hepatic microsomal testosterone hydroxylations

The effects of neonatally administered phenobarbital (PB) on adult rat hepatic microsomal metabolism of testosterone were examined in 60-, 90-, and 120-day-old animals. Phenobarbital-induced imprinting was evident at all ages; however, female rats appeared to be more susceptible to the neonatal effects of phenobarbital than did male rats. In 60-day-old female rats, increased testosterone 2α-hydroxylase activity was observed in microsomes from noninduced rats, whereas decreased testosterone oxidation at all positions except 2α and 15β was observed in microsomes from Aroclor 1254-induced rats. The decreased oxidation of testosterone at specific sites in response to Aroclor 1254 induction was quite dramatic, decreasing the activities to near or below control levels. By contrast, phenobarbital-treated 60-day-old males exhibited approximately a twofold increase in Aroclor 1254-induced 16α and 2α-hydroxylase activities. The pattern of changes in testosterone metabolism observed in phenobarbital-treated animals was different at both 90 and 120 days from that at 60 days. Only minor alterations in the oxidation of testosterone were observed in 90-day-old animals of either sex. In 120-day-old animals the greatest effects of neonatal phenobarbital exposure were on Aroclor 1254–induced 16β-hydroxylase activities. In induced female rats 16β-hydroxylase activity was again decreased to noninduced levels, while in induced male rats a fourfold increase in this activity was observed. These results demonstrate that neonatal exposure to phenobarbital can alter both constitutive and Aroclor 1254–induced testosterone metabolism in adult rats and that the effects of neonatal phenobarbital exposure are age and sex differentiated.     

Post-translational Modification of LipL32 during Leptospira interrogans Infection

Background

Leptospirosis, a re-emerging disease of global importance caused by pathogenic Leptospira spp., is considered the world''s most widespread zoonotic disease. Rats serve as asymptomatic carriers of pathogenic Leptospira and are critical for disease spread. In such reservoir hosts, leptospires colonize the kidney, are shed in the urine, persist in fresh water and gain access to a new mammalian host through breaches in the skin.

Methodology/Principal Findings

Previous studies have provided evidence for post-translational modification (PTM) of leptospiral proteins. In the current study, we used proteomic analyses to determine the presence of PTMs on the highly abundant leptospiral protein, LipL32, from rat urine-isolated L. interrogans serovar Copenhageni compared to in vitro-grown organisms. We observed either acetylation or tri-methylation of lysine residues within multiple LipL32 peptides, including peptides corresponding to regions of LipL32 previously identified as epitopes. Intriguingly, the PTMs were unique to the LipL32 peptides originating from in vivo relative to in vitro grown leptospires. The identity of each modified lysine residue was confirmed by fragmentation pattern analysis of the peptide mass spectra. A synthetic peptide containing an identified tri-methylated lysine, which corresponds to a previously identified LipL32 epitope, demonstrated significantly reduced immunoreactivity with serum collected from leptospirosis patients compared to the peptide version lacking the tri-methylation. Further, a subset of the identified PTMs are in close proximity to the established calcium-binding and putative collagen-binding sites that have been identified within LipL32.

Conclusions/Significance

The exclusive detection of PTMs on lysine residues within LipL32 from in vivo-isolated L. interrogans implies that infection-generated modification of leptospiral proteins may have a biologically relevant function during the course of infection. Although definitive determination of the role of these PTMs must await further investigations, the reduced immune recognition of a modified LipL32 epitope suggests the intriguing possibility that LipL32 modification represents a novel mechanism of immune evasion within Leptospira.     

Extracorporeal shock wave therapy for plantar fasciitis: randomised controlled multicentre trial

Objective To determine the effectiveness of extracorporeal shock wave therapy compared with placebo in the treatment of chronic plantar fasciitis.Design Randomised, blinded, multicentre trial with parallel group design.Setting Nine hospitals and one outpatient clinic in Germany.Participants 272 patients with chronic plantar fasciitis recalcitrant to conservative therapy for at least six months: 135 patients were allocated extracorporeal shock wave therapy and 137 were allocated placebo.Main outcome measures Primary end point was the success rate 12 weeks after intervention based on the Roles and Maudsley score. Secondary end points encompassed subjective pain ratings and walking ability up to a year after the last intervention.Results The primary end point could be assessed in 94% (n=256) of patients. The success rate 12 weeks after intervention was 34% (n=43) in the extracorporeal shock wave therapy group and 30% (n=39) in the placebo group (95% confidence interval - 8.0% to 15.1%). No difference was found in the secondary end points. Few side effects were reported.Conclusions Extracorporeal shock wave therapy is ineffective in the treatment of chronic plantar fasciitis.