Comparison of photosynthesis and leaf ultrastructure on two black locust (Robinia pseudoacacia L.)

Polyploidy is common in many plant species. Up to date, few studies were reported on photosynthesis and leaf anatomy of tetraploid black locust (Robinia pseudoacacia L.), which has considerable value for agriculture and forest. This study compared photosynthesis and leaf ultrastructure on two black locusts. The values of P_n and C_i in tetraploid were significantly higher than those in the corresponding diploids. Significantly lower stomata dimensions (6.0 μm in length and 2.4 μm in width) and tomatal density were observed in 4×. Leaf trichome density was statistically different between 2× and 4×. However, no substantial difference in the ultrastructure of chloroplasts and mitochondria between diploid and tetraploid was observed under any stress. These ultrastructural characteristics may contribute to tetraploid a better protection mechanism than diploid.     

Are plant functional types relevant to describe degradation in arid,southern Tunisian steppes?

Abstract. In the Tunisian arid zone disturbances (e.g. overgrazing and agriculture) and stresses (e.g. aridity, low fertility) drive changes in the structure and functioning of rangelands, with a decrease in perennial plant cover, changes in floristic composition and erosion. Long‐term monitoring requires (1) an understanding of the dynamics of vegetation change and associated ecological processes and (2) identification of relevant indicators. Using data from the arid zone of southern Tunisia we tested the hypothesis that plant functional response types could be used to address these two goals. We identified plant functional response types in response to a gradient of soil and vegetation types characterized by changes in perennial plant cover, dominant species and associated soil types. Vegetation samples were stratified by contrasted vegetation patch types with varying perennial plant cover (1.6 to 22%). We focused our analysis of trait responses within dwarf–shrubs, which are the dominants in typical steppe ecosystems of south Tunisia. Available trait data concerned morphology (plant height, leaf type), regeneration (dispersal mode, phenology and regeneration mode) and grazing value. Although we found it difficult to recognize ‘indicator response types’ that could be used directly to monitor changes in community composition, we were able to identify plant response syndromes that are relevant to long‐term vegetation changes, and in particular degradation processes, in the region. Two main response types were identified: the decreaser type, made up of small or medium chamaephytes with high grazing palatability and the increaser type with medium to tall chamaephytes and low grazing palatability. These response types are proposed as key elements in a state‐and‐transition model of vegetation dynamics in the context of agropastoral disturbances and climatic and edaphic stresses.     

Production of Host‐selective SV‐toxins by Stemphylium sp. Causing Brown Spot of European Pear in Japan

Recently, a new disease known as ‘brown spot of European pear’ caused by Stemphylium sp. appeared on the leaves, twigs and fruits of the cultivar Le Lectier in Niigata Prefecture, Japan. Because Stemphylium vesicarium (teleomorph: Pleospora allii), which causes a similar disease in Europe, has been shown to produce host‐selective SV‐toxins in culture filtrates (CFs), SV‐toxin production by Stemphylium sp. in Japan was investigated. In pathogenicity tests, the pathogen induced severe necrotic spots on the leaves of the European pear cultivar Le Lectier, slight spots on cultivar La France and slight or no spots on cultivar Bartlett. The Japanese pear cultivar Nijisseiki was not affected by the pathogen. Culture filtrates of the pathogen were tested for phytotoxicity on cultivars by a leaf necrosis assay. The sensitivity of cultivars to the CFs was consistent with the susceptibility of cultivars to the pathogen infection, indicating the presence of host‐selective toxins. The toxins were purified from the CFs according to the procedure reported for SV‐toxin purification in S. vesicarium. The results indicated that Stemphylium sp. in Japan produces the same SV‐toxins as S. vesicarium in Europe.     

Sabellid and serpulid worm tubes (Polychaeta,Canalipalpata, Sabellida) from the historical stratotype of the Cenomanian (Late Cretaceous; Le Mans region,Sarthe, France)

The rich Cenomanian assemblage of tube-dwelling polychaete worms of the families Sabellidae and Serpulidae from Le Mans region (Sarthe) is described in detail for the first time in one place; the systematics and the palaeoecology of the species are discussed. The 19 species described belong to 12 genera: Glomerula Brünnich Nielsen, 1931; Filograna Berkeley, 1835; Protula Risso, 1826; Filogranula Langerhans, 1884; Serpula Linnaeus, 1758; Cementula Brünnich Nielsen, 1931; Neovermilia Day, 1961; Dorsoserpula Parsch, 1956; Mucroserpula Regenhardt, 1961; Placostegus Philippi, 1844; Cycloplacostegus Jäger, 2005; Pyrgopolon de Montfort, 1808. Two new species are described: Serpula? pseudoserpentina sp. nov. and Pyrgopolon (Septenaria) cenomanensis sp. nov.     

基于Le Bissonnais法的石漠化区桑树地埂土壤团聚体稳定性研究

石漠化区独特的水土流失作用使该区土壤严重退化,地埂植物作为一种独特的农林复合模式对石漠化区土地质量改善和坡耕地土壤生态修复作用明显,能有效保证坡耕地的生态条件和生产性能。选取石漠化区3种不同管理方式的桑树地埂为研究对象,采用传统湿筛(Cаввинов法)和Le Bissonnais法测定土壤团聚体分布与稳定性特征。结果表明:基于Cаввинов法测定的土壤团聚体稳定性以天然林最好,桑埂自然生草地和清草地相对居中,桑埂农地最差;3种管理方式的桑树地埂土壤团聚体稳定性指数(ASI)随地埂距离均表现为ASI_90cm > ASI_60cm > ASI_30cm,主要原因在于桑树地埂对坡耕地土壤团聚体影响的作用范围主要集中在距株30 cm以内,而在地埂30 cm以外田面农耕活动对土壤团聚体结构影响较大,而受桑树地埂影响作用较小。基于Le Bissonnais法快速湿润(FW)处理后土壤团聚体集中分布在0.5-0.25 mm之间,慢速湿润(SW)和湿润振荡(WS)处理后团聚体主要分布在5-1 mm之间。Le Bissonnais法处理后土壤团聚体稳定性表现趋势与Cаввинов法一致,3种处理后的团聚体分形维数D、MWD和GMD均表现为FW < SW < WS。Le Bissonnais法FW和SW处理后团聚体稳定性指标与Cаввинов法达到极显著相关,说明Le Bissonnais法测定石漠化区土壤团聚体稳定性是可行的;石漠化区土壤团聚体稳定性与有机质和粘粒含量呈显著正相关(0.586 ≤ R ≤ 0.864),这说明石漠化区土壤团聚体稳定性是以上两种土壤胶结物质的黏聚作用形成的,且两种土壤胶结物质对土壤消散作用和粘粒膨胀作用引起的团聚体破坏抵抗性强烈,而对低强度机械干扰引起的团聚体破碎没有明显抵抗性,研究结果对石漠化区坡耕地土壤保持具有重要指导意义。     

Les pointes pseudo-Levallois du gisement moustérien Le Rissori, à Masnuy-Saint-Jean (Hainaut, Belgique)

The 1985-1992 excavation of the Middle Palaeolithic site Le Rissori provided 202 pseudo-Levallois points, distributed in four successive Mousterian series covering a period of time of about 200,000 years. The reference object is the typical five and more sided polygonal point. It is an asymmetrical variety of “débordant” flakes with their own striking platform, at the difference of classical “débordant”, the obliquity of which makes the difference in the following three categories : typical polygonals, atypical polygonals, and classical subtriangulars. The operating scheme - which is the same for all the categories- gives some large and thick flakes after “débitage”. The typical pseudo-Levallois points (polygonal and classical of type A) show two thick sides : the butt and the concave reshaped “débordant” side which is corresponding to the partial overcutting of the active striking platform of an uni- or bipolar recurrent Levallois core. Their function stands in latero-longitudinal (distal or proximal) convexities restoration, the usual process of which can only be restored with difficulties, because of the importance of the removed volume.Typical, polygonal and classical points become perfectly integrated into the Levallois system ; their technological scheme shows a lot of similarities, evoking an antesaalian evolution and origin. The pseudo-Levallois point so appears like a product with a technological vocation, which is revealing a latero-longitudinal restoration. The pseudo-Levallois point is moreover confirming the presence of a uni- or bipolar recurrent Levallois “débitage” with blades or lengthened flakes.     

The “miacids” (Carnivoraformes,Mammalia) from the Early Eocene locality of Le Quesnoy (MP7, France); first occurrence of Vassacyon in Europe

We describe here “miacid” taxa from the Early Eocene Paris Basin locality of Le Quesnoy (Oise, France). We describe the new species Vassacyon taxidiotis, the first European record of this genus. The other “miacids” identified from Le Quesnoy are Miacis latouri and Gracilocyon solei. The P4 of G. solei is described here for the first time. Its morphology (e.g., wide protocone, short postmetacrista) supports a close relationship with Miacis rundlei from Abbey Wood (MP8 + 9, England). The latter species is therefore classified as Gracilocyon rundlei. Three new tooth positions are known for Miacis latouri: P4, p4 and m2. They support its reference to Miacis. These specimens imply that the European species is more basal than the North American species. The fauna from Le Quesnoy shares with Dormaal the presence of Miacis latouri and Gracilocyon solei, but the “miacid” fauna from Le Quesnoy also contains Vassacyon taxidiotis. The presence in Le Quesnoy of the two former taxa supports a reference to MP7 level of the French locality. The presence of three distinct genera in European localities show that the “Miacidae” were diversified in Europe, as previously observed in North America. The genera Gracilocyon, Miacis, and Vassacyon probably dispersed from Europe to North America during the Palaeocene/Eocene boundary.     

Measurement of intratissue bioelectrical low frequency impedance: A new method to predict per-operatively the destructive effect of cryosurgery

A new cryosurgical technique is described, per-operatively using a device which measures the transtissue bioelectrical LF impedance. This technique enables the investigator to preselect and to freeze with precision the area to be cryodestroyed.     

New data on Late Pleistocene small vertebrates from northern France

Quaternary small vertebrate assemblages from northern France, and more generally from northwestern Europe, are poorly recognized, and studied less than those from more southern, Mediterranean areas. However, important sites of human occupation are often found in these northern areas, with significant issues related to the occupation of these sites by Neanderthals and previous humans, as well as faunal dynamics under climatic pressure. In this paper, we present preliminary results from the study of small vertebrate assemblages from two Late Pleistocene sites of northern France: Mutzig (Alsace) and Le Rozel (Normandy). Both are ancient rock-shelters that have been excavated recently and have yielded evidence of Neanderthal occupation, but in very different contexts: Le Rozel is located in a coastal area of northwestern France contemporaneous with a temperate period, while Mutzig is located at the foot of the Vosges mountains in northeastern France and was occupied during a cold period. Consequently, even if these two sites are chronologically close to each other, differences in faunal composition are observed and discussed in relation to the geographic, climatic and biochronological context, in comparing the results from small vertebrates with those from other disciplines (numerical dating, large mammals).     

Studying health histories of cancer: A new model connecting cancer incidence and survival

The results of recent experimental and epidemiological studies provide evidence on the connection between carcinogenesis, cancer progression, and aging. Existing models, however, are traditionally focused only on one of these aspects of health deterioration. In this paper, we derive a new model of cancer, which describes the connection between the ages at disease onset, the duration of disease, and life span of respective individuals. The model combines ideas used in the two hits model of carcinogenesis with those used in the Le Bras multistate model of aging with constant transition intensities. The model is used in the joint analyses of the US demographic mortality data and SEER data for selected cancers. The results show that the developed approach is capable of explaining links among health history data and provides useful insights on mechanisms of cancer occurrence, disease progression, other aging-related changes, and mortality. Further developments of this model are discussed.