Deep‐water cirripedes colonizing dead shells of the cephalopod Nautilus macromphalus from New Caledonian waters

Fossil cephalopods are frequently encrusted by epibionts; however, determining whether encrustation occurred prior to or post‐mortem to the host, and whether the final environment of deposition corresponds to the habitat of encrustation is complex. The present paper describes cirripede epibionts, their calcareous bases and their attachment scars on 6 post‐mortem shells of Nautilus macromphalus, collected from deep water off New Caledonia. The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles. Live cirripedes included a Metaverruca recta, with articulated opercular plates and organic tissue (on a shell that had been exposed on the sea floor for at least 150 years), and specimens of Hexelasma velutinum, one of which was partly attached to an internal surface of a shell. The disposition of verrucomorphs indicates that most Nautilus shells were colonized post‐mortem rather than during a floating stage. However, as cirripedes are known to have colonized living Nautilus, some Hexelasma, preserved only as calcareous eroded bases, may represent specimens that settled on a living Nautilus. The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells, with deeper and discolored traces preserved on old and degraded shells. Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon, Anellusichnus ellipticus, is proposed to accommodate them. Importantly, verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars, and, thus, will be difficult to detect in the fossil record.     

铁路路堑边坡植被恢复调查研究

植被在边坡生态系统中有着非常重要的作用,具有涵养水源、保持水土的功能.选择四川省成昆铁路沿线不同坡向的土质路堑边坡和岩质路堑边坡,对边坡植物群落的植被类型及其结构特征、边坡植被恢复物种组成及其特征进行了调查研究.结果表明:铁路边坡自然定居物种共103种,隶属48科,全部植物中,常绿灌木2种,落叶灌木9种,藤本植物7种,1 a生草本20种,2 a或2 a以上草本植物49种;蕨类植物15种.群落物种的丰富度虽然较高,但是主要由草本植物构成,结构层次简单,应该适当的在边坡上栽植灌木或小乔木,形成坡面上乔、灌、草或草、灌相互映的群落景观.     

Sites of Persistence of Lumpy Skin Disease Virus in the Genital Tract of Experimentally Infected Bulls

The objectives of this work were to determine the site of persistence of lumpy skin disease virus (LSDV) in bulls shedding the virus in semen for a period longer than 28 days, to determine if the virus is present in all fractions of semen and to study lesions that developed in the genital tract. Six serologically negative postpubertal bulls were experimentally infected with a virulent field isolate of LSDV. The polymerase chain reaction (PCR) was performed on sheath washes, vesicular fluid, supernatant and cell‐rich fractions of semen from day 10 to day 26 postinfection (p.i.). Bulls that were positive by PCR on the whole semen sample collected on day 28 p.i. were slaughtered and tissue samples from their genital tracts submitted for histopathological evaluation, immunoperoxidase staining, virus isolation and PCR. Two of the bulls developed severe lumpy skin disease (LSD) and were found to be shedding viral DNA in their semen on day 28 p.i. Viral DNA was identified in all semen fractions from all bulls, but mostly from the cell‐rich fraction and from the severely affected bulls. The PCR assay was positive on postmortem samples of testes and epididymides from the two severely affected bulls. Virus could be recovered from the testes of these two bulls and from the epididymis of one of them. Immunoperoxidase staining was positive for LSDV staining in sections of testes and epididymides exhibiting necrosis. This study suggests that the testis and epididymis are sites of persistence of LSDV in bulls shedding virus in semen for prolonged periods and revealed that viral DNA is present in all fractions of the ejaculate.     

Effects of reducing leaf area and tuber number on the growth rates of tubers on individual potato plants

Summary Potato plants (Solanum tuberosum L. cv. Ostara) were grown in nutrient solution culture in a controlled environment. Growth rates of individual tubers were determined daily by measuring the increase in their volume. Decreasing the source:sink ratio of individual plants by removing half of the leaf area, decreased tuber growth rate per plant by 50%. Increasing the source: sink ratio of individual plants by cooling to 8°C, or by removing individual tubers of known growth rate, increased the growth rate of non-cooled, remaining tubers within 2–4 days. The potential of the tubers to increase their growth rates was not related to the date of tuber removal after tuber initiation. It is concluded that during the phase of linear tuber bulking, tuber growth is neither limited by pathway nor sink, but by the source capacity of the plant.

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Zusammenfassung Kartoffelpflanzen (Solanum tuberosum L. cv. Ostara) wuchsen in N?hrl?sung unter kontrollierten Umweltbedingungen (14 h Tagesl?nge, 22°C/18°C Tag/Nachttemperatur, 60–80% relative Luftfeuchtigkeit, Licht-intensit?t in Pflanzenh?he ≈380 μE m⁻² s⁻¹). Die Wachstumsraten der einzelnen Knollen wurden t?glich aus ihrer Volumenzunahme bestimmt. Die Auswirkungen von Source- und Sink-Manipulationen auf die Wachstumsraten der Knollen wurden w?hrend der Phase linearen Knollenwachstums untersucht. Eine Reduzierung der Source-St?rke einzelner Pflanzen durch Entfernen jedes 2. Fiederblattes oder eines von 2 gleichwertigen hauptstengeln pro Pflanze bewirkte eine sofortige Abnahme des Knollenwachstums pro Pflanze um 50% (Abb. 4). In den meisten F?llen nahm auch die Wachtstumsrate der einzelnen Knollen an den Pflanzen um etwa 50% ab (Abb. 5). Durch Kühlung einzelner Knollen auf +8°C wurden deren Wachstumsraten im Durchschnitt von 4,5 auf 1,6 cm³ d⁻¹ gesenkt, w?hrend gleichzeitig die Wachstumsraten der ungekühlten Knollen von 2,8 auf 5,2 cm³ d⁻¹ anstiegen (Tab. 1). Das Entfernen einzelner Knollen, die bis dahin durch-schnittlich zu 60% am Gesamtknollenwachstum pro Pflanze beteiligt waren, führte innerhalb von 2–4 Tagen zu einem mehr als doppelt so schnellen Wachstum der an den Pflanzen verbliebenen Knollen, so dass das Gesamtknollenwachstum pro Pflanze nicht signifikant ver?ndert wurde (Abb. 1). Hierbei wurden die Wachstumsraten aller an der Pflanze verbliebenen Knollen erh?ht, wobei Wachstumsraten von mehr als 8 cm³ pro Einzelknolle und Tag erreicht wurden (Abb. 3). Die F?higkeit der Knollen, ihre Wachstumsrate dem jeweiligen Assimilatangebot anzupassen, war nicht davon abh?ngig, zu welchem Zeitpunkt nach der Knolleninduktion (10–30 d) einzelne Knollen entfernt wurden (Abb. 2). Aus den Untersuchungen wird gefolgert, dass in der phase des linearen Knollenwachstums eine Limitierung des Knollenwachstums weder durch den transportweg noch durch die Speicherf?higkeit der Knollen bewirkt wird, sondern durch die F?higkeit des oberirdischen Sprosses, Assimilate zur Verfügung zu stellen.

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Résumé Des plantes de pommes de terre (Solanum tuberosum L. cv. Ostara) sont cultivées dans une solution nutritive sous atmosphère contr?lée (longueur de jours 14 h; températures jour/nuit 22°C/18°C; humidité relative de l'air 60 à 80%; intensité du rayonnement photosynthétique à hauteur de la plante ≃380 μF m⁻² s⁻¹). Le grossissement des tubercules est déterminé chaque jour en mesurant l'augmentation de leur volume. Les effets de la source d'assimilation et du puits d'absorption sont analysés pendant la phase linéaire de grossissement des tubercules. Une diminution du rapport source: puits d'absorption est obtenue en supprimant la moitié de la surface foliaire de chaque plante. Le grossissement des tubercules diminue en conséquence de 50% (figure 4). Mis à part quelques exceptions, les taux de croissance des tubercules individuels baissent également de 50% (figure 5). Le refroidissement de certains tubercules d'une même plante à 8°C entra?ne une diminution moyenne de leur grossissement de 4,5 à 1,6 cm³/jour. Dans le même temps, les autres tubercules voient leur croissance augmenter de 2,8 à 5,2 cm³/jour (tableau 1). La suppression de certains tubercules qui avaient contribué pour 60% au grossissement total obtenu par plante, entr?ne une augmentation de croissance de plus de 100% des tubercules restants, ceci en moins de 2 à 4 jours. De ce fait, la croissance totale, par plante n'est pas significativement inférieure (figure 1). Après suppression de certains tubercules, on constate que pour tous les tubercules restants leur grossissement augmente et le taux maximum de croissance atteint 8 cm³/jour (figure 3). Les tubercules ajustent leur grossissement en fonction de l'apport effectif de photosynthèse sans liaison avec la date de suppression de certains tubercules après leur initiation (figure 2). En conclusion, pendant la phase linéaire de grossisement, la croissance des tubercules n'est pas limitée par le puits d'absorption, mais par la capacité de la source d'assimilation de la plante.

     

Prevalence and inheritance of canine elbow dysplasia in German Rottweiler

A total of 2114 scores of elbow arthrosis from the official screening programme of the German Rottweiler Breeding Association (ADRK) were analysed in respect of prevalence and genetic disposition. 45.8% showed no signs of arthritis, 40.6% were scored in Grade 1 with minor osteophytes and 13.6% were affected by arthritis of clinical relevance (Grade 2 and 3). REML estimates showed a heritability of 28% and a litter variance of 6.4%. The only significant environmental fixed effect was gender. 39.1% of the male and 51.5% of the female were free from ED which corresponds with 19.2% of the male and only 8.8% of the female in the critical ED classes of Grade 2 and 3. Differences between the years of examination could be explained by genetic gain. Month of birth as well as age at examination, in the range covered by this study, was not significant. It was stated that the effect of bodyweight should be tested before starting a breeding programme.     

Light microscopy and image analysis of thin filament lengths utilizing dual probes on beef, chicken, and rabbit myofibrils

Image analysis procedures for immunofluorescence microscopy were developed to measure muscle thin filament lengths of beef, rabbit, and chicken myofibrils. Strips of beef cutaneous trunci, rectus abdominis, psoas, and masseter; chicken pectoralis; and rabbit psoas muscles were excised 5 to 30 min postmortem. Fluorescein phalloidin and rhodamine myosin subfragment-1 (S1) were used to probe the myofibril structure. Digital images were recorded with a cooled charge-coupled device controlled with IPLab Spectrum software (Signal Analytics Corp.) on a Macintosh operating system. The camera was attached to an inverted microscope, using both the phase-contrast and fluorescence illumination modes. Unfixed myofibrils incubated with fluorescein phalloidin showed fluorescence primarily at the Z-line and the tips of the thin filaments in the overlap region. Images were processed using IPLab and the National Institutes of Health's Image software. A region of interest was selected and scaled by a factor of 18.18, which enlarged the image from 11 pixels/microm to approximately 200 pixels/microm. An X-Y plot was exported to Spectrum 1.1 (Academic Software Development Group), where the signal was processed with a second derivative routine, so a cursor function could be used to measure length. Fixation before phalloidin incubation resulted in greatest intensity at the Z lines but a more-uniform staining over the remainder of the thin filament zone. High-resolution image capture and processing showed that thin filament lengths were significantly different (P < 0.01) among beef, rabbit, and chicken, with lengths of 1.28 to 1.32 microm, 1.16 microm, and 1.05 microm, respectively. Measurements using the S1 signal confirmed the phalloidin results. Fluorescent probes may be useful to study sarcomere structure and help explain species and muscle differences in meat texture.     

戊型肝炎病毒研究新进展

戊型肝炎病毒(hepatitis Evirus,HEV)是非甲非乙型急性肝炎的病原体,主要经粪-口途径传播,也有报道可以通过血液传播。戊型肝炎在亚洲、非洲及美洲的墨西哥等发展中国家常呈爆发流行,我国1986-1988年在新疆曾经发生戊型肝炎暴发流行[1],而在包括发达国家在内的世界各地呈散在传