Observations sur l'activité de migration de la grande alose Alosa alosa L. en Loire (France)

We studied the migratory activity of shad (Alosa alosa Linné) in the middle part of the Loire river, using stop net catches, in 1984.The migration started in the beginning of April, instead of February, as more usual. The end of migration is not precisely known, because of adverse hydrological conditions.During migration, the shad principally used the channel with the highest current velocity. The migration was disturbed by the presence of obstacles (weirs, dams of nuclear power stations).The daily and hourly activity of migration was strongly correlated with variations in water temperature. Shads did not run up at temperatures below 11°C. The upstream limit of ditribution was situated at more than 500 km from the estuary.

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Observations sur l'activité de migration de la grande alose Alosa alosa L. en Loire (France)

     

小叶章种群高度的季节动态

探讨了三江平原以小叶章为优势种的典型草旬、沼泽化草甸、沼泽３个植被类型中小叶章种群高度的变化规律。结果表明,在３个类型中,种群高度的季节动态均呈单峰型,极大值均出现在７月末,分别为１１２．６７ｃｍ、１０１．６１ｃｍ、８３．８８ｃｍ。ＨＡＧＲ的季节动态在７月末之前〉０,之后〈０;典型草甸和沼泽化草甸的极大值出现在６月末至７月中旬,沼泽则出现在６月中旬至６月末;极小值典型草甸出现在８月末至９月中旬,而     

Growth and differentiation of secondary malpighian tubules in the cockroach,Periplaneta americana

Four differentiated Malpighian tubules (primary tubules) extend from the junction of the midgut and hindgut in newly hatched Periplaneta americana. Secondary tubules begin to develop near the base of the primary tubules before hatching and successive nymphal molts. The newly initiated tubules undergo cell division and extensive elongation through the middle of the following intermolt period. During this time, the cells of the distal, middle, and lower middle tubule regions are surrounded by a cellular sheath, have few cytoplasmic processes extending along their basal surfaces, have a small or nonexistent lumen, and contain extremely dilated cisternae of endoplasmic reticulum. The cellular sheath differentiates into the muscle which coils around the mature tubule. Tubules which begin development toward the end of one intermolt period begin to undergo cytodifferentiation toward the end of the next intermolt period. By the middle of an additional intermolt period, the basal infoldings and microvilli of cells in the distal, middle, and lower middle regions have the conformations typical for those regions in differentiated tubules; granular concretions and stellate cells are present within the middle region of the tubule.     

Species Recognition by Song in the Veery (Catharus fuscescens: Aves)

Territorial male veeries (Catharus fuscescens) were presented with three series of reorganised songs to determine the functional properties of song structure. Songs consist of three parts: a low frequency initial phrase, a higher frequency middle phrase, and again a lower frequency end phrase. The latter two consist of vibrato syllables. Three series of experiments were performed, using various combinations of song syllables. In Series I, songs consisted of repetitions of a single syllable, one from each part of the song. Veeries responded to syllables from the middle and end phrases as to normal songs, both in localisation and in vocal responses. However, they showed little localisation and vocalisation responses to the introductory syllables. In Series II and III, veeries responded significantly more to songs in which syllables from the middle and end phrases were presented in proper sequence, rather than not. The minimum requirements for intraspecific recognition were determined in relation to the number and order of syllables in the song.     

Ion etching of bacteriophage lambda: evidence that the right end of the DNA is located at the outside of the phage DNA mass.

Bacteriophage lambda was etched in an Ar+ plasma under conditions in which the capsid and some of the DNA were eroded (by sputtering) from the particle surface. Analysis of the DNA remaining in etched phage demonstrated an enrichment in sequences derived from the left end and middle of the genome; sequences from the right end were selectively lost. The results suggest that the DNA in the mature phage is arranged with its left end toward the center and its right end toward the exterior of the overall DNA mass. Since the left end is the first to enter the phage prohead, the results are most compatible with the view that prohead filling also proceeds from the center to the exterior of the cavity. The suggested arrangement of lambda DNA is comparable to that observed in phage T4 and is consistent with the spiral-fold model of packaged DNA.     

L'oeuf de Myrmeleotettix maculatus Thunb. (Orthoptera : Acrididae): Absorption d'eau et structure fine des enveloppes

Water absorption and fine structure of the egg shell have been studied in the eggs of Myrmeleotettix maculatus (Orthoptera : Acrididae). At the anterior pole of these eggs, there is a respiratory plastron and at the posterior end, behind the ring of micropyles, many minute holes can be seen. Eggs of M. maculatus incubated on wet filter paper at 30°C absorb water before diapause between the 5th and the 25th day after oviposition. The period of water absorption coincides with the serosal cuticle secretion. The increase in volume of the egg does not seem to involve any fragmentation in the chorion. The chorion is composed of 3 layers (upper, middle and lower). The middle layer, the thickest one, contains twisted elements with a paracrystalline structure. During the first days of incubation, the vitelline membrane becomes changed. In the newly laid egg, it is granular and homogeneous. Five days later, 4 layers with different structures can be distinguished. After 30 days, the serosal cuticle presents a thin epicuticule and a thick lamellated endocuticule with many pore canals.     

Conodontes de la coupe de Reun Ar C'Hrank en Lanvéoc (Rade de Brest) emsien du massif Armoricain (France) corrélations biostratigraphiques

In the Reun ar C'Hrank section (Rade de Brest), the Conodonts from just above the base of the Beg an Arreun Formation of the Troaon Group in the Armorican Massif indicate the Polygnathus laticostatus Zone, which belongs to the highest Zlichvian and the base of the Dalejan. Species of Icriodus from the same beds indicate a correlation with the lower and middle part of the Hierges Formation, which represents the Upper Emsian in the Ardennes. Conodonts from Le Fret Formation are tentatively assigned an Upper Emsian/Dalejan age.     

Fine structure of scorpion spermatozoa (Buthus occitanus; buthidae,scorpiones)

The mature spermatozoa of Buthus occitanus are threadlike in shape and divided into sperm head, middle piece, and end piece. The sperm head is corkscrew shaped anteriorly and in this region bears an unusual acrosomal complex consisting of a ring-shaped acrosomal vacuole associated with a subacrosomal filament and a perinuclear amorphous component. The subacrosomal filament extends posteriorly into a tube-like invagination of the elongated nucleus. The middle piece is characterized by elongated mitochondria which spiral around the anterior part of the flagellum in an extended collar separated from the flagellum by an extracellular cleft, termed the central flagellar tunnel. In addition to the usual 9 × 2 + 2 axonemal pattern in flagella, 9 × 2 + 1 and 9 × 2 + 3 patterns also were observed. The end piece is represented by the free flagellum. Similarities and diversities of scorpionid spermatozoa are discussed with respect to systematic relationships.     

Ultrastructure of the Feeding Apparatus of Rhabdodemania minima Chitwood, 1936 (Enoplida: Rhabdodemaniidae)

The feeding apparatus of the marine nematode Rhabdodemania minima Chitwood, 1936 has been examined with light and transmission electron microscopy. The buccal capsule consists of a posterior region with smooth walls bearing three sets of three minute denticles at its posterior end and three large onchia in its mid region; a middle region with grooved walls; and an anterior region with costae and six odontia. The anterior and middle portions of the buccal capsule are enveloped by the cephalic cuticle, whereas the posterior region, which is set off from the middle region by a buccal seam, is partially enveloped by the anterior end of the esophagus. Two subventral esophageal glands open into the lumen of the esophagus. Secretions of each of three paraesophageal glands are conveyed through a duct in each of the three corresponding corners of the buccal wall to an opening between labia. A pair of wing-like thickenings, termed pterons, embraces the duct of each paraesophageal gland in the posterior and middle regions of the buccal capsule. A model of how the buccal capsule operates is proposed and tested. Morphological and functional aspects of the buccal apparatus and cephalic cuticle are compared with those of other taxa of the Enoplida, and their phylogenetic implications are discussed.     

Implications paléobiogéographiques de la découverted'une nouvelle localité éocène à vertébrés continentaux en afrique nord-occidentale: El Kohol (Sud-Oranais,Algérie)

The new fossil locality of El Kohol is located on the southern flank of the Saharan Altas, near Brezina (Algeria). It has been discovered in a thick Palaeogene continental series divided into 4 members: a transitional gypsiferous member, a lower red detritic member, a middle marly-calcareous member, and an upper red detritic member. The new flora and fauna have been obtained by excavation and washing-screening of a marly level of the middle member. The main finds are charophytes, lower vertebrates, a marsupial and eutherian mammals (lipotyphlan Insectivora, hyracoids, creodonts and Proboscidea). Geological and palaeontological data allow to refer these fossil remains, at least provisorily, to the end of the early Eocene. Palaeobiogeographical comments are made about forms with Holarctic affinities.     

On the oesophagus of ascaris lumbricoides

Summary The oesophagus ofAscaris lumbricoides is built up by a muscular-epithelial part containing the ordinary muscle fibres which run from the three sides of the oesophagus lumen towards the periphery and a system of fibres and fibrous plates at the margin of the triradiate oesophagus lumen. In four complete series ofA. lumbricoides (males and females) the nuclei of both kinds of fibres were constant in arrangement and number. The glandular system of the oesophagus consists of a large dorsal gland and two smaller subventral ones. The opening of the dorsal gland is at the anterior end of the oesophagus in the middle between nerve ring and lips. The openings of the two subventral glands are placed in the posterior end of the oesophagus in the middle of the two subventral slides at the same level. The dorsal gland fills with its ramifications the space between the muscle fibres of the three sectors with the exception of the most anterior end of the oesophagus before the opening of the dorsal gland and the subventral sectors in the posterior end of the oesophagus. The subventral sectors of the posterior end are filled by the ramifications of the two subventral glands. The ramifications of these three glands are connected. The three nuclei of the three glands have their place in the posterior end of the oesophagus, the nuclei of the subventral glands are situated in the most ventral part of each subventral sector close to each other, the nucleus of the dorsal gland has a complicated form and extends over the whole breadth of the dorsal sector. With 10 figures in the text.     

Phytosociological and environmental gradients in a sector of the Western Desert of Egypt

Summary The climatic and physiographic features of the Western Desert of Egypt vary gradually from the Mediterranean coast inland. The present study provides an analysis of the gradients exhibited by these environmental variations and their relationships with vegetational gradients and the phytosociological behaviour of species in a sector along the Cairo-Alexandria desert road. The multivariate analyses of the vegetation lead to the recognition of six interrelated vegetational groupings which were distributed along a climatic gradient of increasing aridity, and an edaphic gradient of increasing sandiness and decreasing salinity and level of total phosphorus. These groupings were distinguished into three sets: a set ofConvolvulus-Helianthemum-Artemisia, andHelianthemum-Echiochilon, a set ofAnabasis, andSalsola-Anabasis, and a set ofAsphodelus-Noaea andThymelaea-Anabasis-Noaea groupings. The first set occupies the more arid end of the climatic gradient and the end of the coarse texture, low salinity and low levels of total phosphorus of the edaphic gradient. The second set occupies the opposite end of the edaphic gradient and the middle position of the climatic gradient and the middle position of the climatic gradient, and the third, the middle position of the edaphic gradient and the less arid end of the climatic gradient. Taxonomic nomenclature is according to T?ckholm (1974). The multivariate analyses were carried out using a Burroughs B6700 at the Computer Center of Utah State University, and supported by the U.S. Desert Biome. The authors are indebted to W. Valentine, H. C. Romesburg and K. Marshall for their assistance with data processing.     

河漫滩湿地生态阈值——以二卡自然保护区为例

以典型河漫滩湿地 —— 二卡自然保护区为研究区域,进行生态阈值研究。根据湿地补给河流 —— 海拉尔河的月均流量频率分布特征,选取58.72 m³/s(P=74.6%)、119.26 m³/s(P=44.4%)、190.35 m³/s(P=23.8%)分别代表河流的低、中、高径流期,分析各径流期湿地分布特征。结果表明,低、中径流期内草本沼泽及盐化沼泽所占比例较高,而高径流期则以季节性河流湿地及湖泊湿地为主。低径流期内,作为湿地中心区的湖泊湿地景观破碎度出现一个较明显的跃变,由中径流期的0.57增加到1.37。此时的湿地状态可近似的作为区域的生态阈值,即维持湿地面积占全区域面积的43.03%。而中、高径流期湿地面积比例可近似作为保护区湿地面积的适宜值和理想值,分别为53.66%和69.53%。其研究结果为二卡自然保护区的管理及保护提供支持,并为河漫滩湿地研究提供思路。     

冰川退缩地26种丛藓科植物叶中肋细胞结构的研究

该研究应用离析方法,并通过光学显微镜对新疆天山一号冰川退缩地的26种丛藓科植物叶片中肋细胞的形态结构进行比较分析,结果表明:(1)丛藓科植物叶片的中肋细胞的长、宽和细胞壁厚度、纹孔场数目及细胞端尾数目在一定程度上存在着差异,反映出各中肋细胞的功能及导水作用在同属及不同属植物之间存在一定的差异。(2)中肋细胞的端尾多以及细胞壁的波状结构都具有增强细胞间的联系、提高机械固着和支撑作用。(3)不同生境下,中肋细胞侧壁的纹孔场数目能有效控制导水和物质交换的速度。这些特征可能都是冰川地区苔藓植物对恶劣生境的积极响应,具有一定的生态学和分类学意义。     

Nouvelle approche de l’art rupestre de l’Atlas saharien : les figurations de la période tardive

Figurations in Atlas have been studied numerous times, namely by Flamand and Frobenius between 1891 and 1914, by Vaufrey in 1939 and by Lhote between 1955 and 1970. And finally there were Iliou’s¹ and Hachid’s theses in the 1980s and Amara’s thesis in 2001. The study of the Atlas figurations discovered since 1847 brought new data on the engravings from the recent period. The originality of the engravings lies in the appearance of new themes, which had been unknown until yet. The presence of metal weapons figures enriches the records of the Atlas rock Art. The alphabetical signs, another new theme, give an identity to this Art. The work undertaken in this vast region raises the problem of the persistency of the Neolithic culture. All the figurations show some aspects of the evolution, which become permanent, mostly at the end of the recent period.     

Un nuevo basicráneo de titanosaurio de la Formación Allen (Campaniano-Maastrichtiano), Provincia de Río Negro, Patagonia, Argentina

We describe a new titanosaurian braincase (MML-194), from the Upper Cretaceous (middle Campanian-lower Maastrichtian) of Río Negro Province, Argentina. Among titanosaurs, this specimen resembles Bonatitan reigi, more than any other member of the clade; the similarity is based on the supraoccipital protuberance bearing a median groove (also present in Saltasaurus and Rapetosaurus), the prominent basal tubera, the exit for the nerve VII located on the prootic crest, the occipital condyle and the foramen magnum almost of the same width. This material allows to observe some internal structures that are not appreciable in other titanosaurs, such as the pituitary cavity, the dorsum sellae and the foramen for the passage of the internal carotids, among other characters. The specimen MML-194 and Bonatitan were exhumed of same geological unit, the Allen Formation, from which have also been collected fossil eggs assignable to sauropods (megalooliths), for what is not unlikely that some of these taxa has been responsible of the laying of those eggs.     

Initial analysis of the molecular image of pamlin, a sea urchin cell adhesion protein, by transmission electron microscopy

Pamlin, an important extracellular protein required early for sea urchin embryogenesis, is readily isolated from the embryos of Hemicentrotus pulcherrimus . A molecular image analysis of pamlin was conducted using immuno-electron microscopy, rotary shadowing and negative staining technique-applied electron microscopy. The electron microscopy showed that a monoclonal antibody to the pamlin α-subunit bound to a position 13.5 nm from one end of a purified 255 kDa pamlin molecule, which is a 132 nm long and 6.8 nm wide linear structure. The pamlin structure is composed of three subunits, a 47 nm long 52 kDa α-subunit that attaches to one end of a 105 nm long 180 kDa β-subunit, and a 15.6 nm diameter globular 23 kDa γ-subunit that binds to the middle of the β-subunit. The α- and β-subunits together form a 125–140 nm linear structure. Intermolecular aggregation frequently occurred between the free end of two β-subunits of the αβγ pamlin molecule, leaving the entire α-subunit surface free. Occasionally associations between the ends of α-subunits, or between an α-subunit and the middle of a β-subunit also occurred, but no aggregations of pamlin formed through the γ-subunit. These homophilic molecular aggregations of pamlin formed a large supramolecular network. In addition, the single pamlin molecule rounded at one end under high calcium ion concentration to form a 'loop', suggesting the presence of a calcium sensitive region in the molecule.     

Presence de Graptolites de l'Arenig moyen a la basede la Formation de Postolonnec (Massif Armoricain); Consequences stratigraphiques et paleogeographiques

The lowest part of the Postolonnec Formation (western Brittany) can be assigned to the middle Arenig Didymograptus nitidus Zone on graptolite evidence. Preliminary information on the Chitinozoa agrees with this age assignment, which defines more precisely the age of the underlying Grès armoricain Formation and also demands reconsideration of the problems associated with early Ordovician palaeogeography and sedimentology in the Massif armoricain.     

Distant effects of toxic agents

Toxic solutions applied at one end of a Nitella cell 6 cm. long may produce little or no visible change in the structure of the protoplasm at the place of application but if the opposite end is covered with water its protoplasm soon disintegrates. If the middle of the cell is covered with mineral oil this region remains normal in appearance for half an hour or more. The result is due to the movement of substances in the cell. The loss of substances at the end where the toxic agent is applied results in loss at the opposite end if it is covered with water since water enters and travels along inside the cell carrying substances with it. This causes injury at the spot where the water enters. The conception developed here differs fundamentally from the usual view that the effects of injury spread gradually from the region where the toxic agent is applied to the immediately adjoining regions and thence to more remote places. The change produced by loss of substances produces an interesting pattern which deserves study.