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Ultrastructure of stemmata (larval eyes), stemmatal nerves, and the optic neuropils of 5th-instar larvae of cotton bollworm, Heliothis armigera (Hübner) (Lepidoptera : Noctuidae), were examined with scanning and transmission electron microscopes. Six stemmata are on each side of the head. Each stemma consists of 7 retinula cells arranged into 2 tiers. Stemmata I and II have 4 distal retinula cells and 3 proximal cells, the other 4 stemmata (III–IV) have 3 distal cells and 4 proximal cells. Stemmata I and IV have a short proximal rhabdom and the rhabdomere of each proximal cell has its microvilli projecting in only one direction. On the other hand, each stemma (in stemmata II–V) has a long proximal rhabdom and the rhabdomere of each proximal cell has microvilli pitched in several different directions relative to the horizontal plane. An axon projects proximally from each retinula cell body. The stemmatal nerve is composed of the 42 retinular axons from all of the 6 stemmata on the same side of the head. Each stemmatal nerve projects to the ipsilateral optic neuropil. Axons from each stemma are in a fasicle (within the stemmatal nerve), which consists of 7 axons, 3–4 of them are thick and terminate synaptically in the proximal neuropil; the others are thinner and terminate in the distal neuropil. Organelles, particularly lysosomes, undergo ultrastructural transformations relative to ambient light levels. The functional significance of abovementioned structures are discussed in light of current knowledge.  相似文献   

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The Malpighian tubules of nymphal Aeshna cyanea (Odonata : Aeshnidae) were examined by light and electron microscopy. The 1st-instar nymphs have only 3 branchless tubules. With proceeding nymphal stages, these lengthen and branch. Also, additional tubules bud from the gut and show the same pattern of growth and branching, until in the final instar up to 21 separate tufts of branched tubules are present. A serpentine trachea/tracheole and a cross-striated muscle are helically wound around each tubule in close apposition. Isolated tubules show twisting movements for several days. Contraction of the muscle is responsible for fast coiling movements, while the slow decoiling movements probably depend on elastic deformations of the accompanying trachea, the basal lamina and the tubule cells, the latter showing an elaborate cytoskeleton and multiple adhesive junctions.The tubular epithelium consists of 4 types of cells. The distal segment is composed of ion transporting cells and terminates with a short, solid tip segment of undifferentiated cells. The intermediate segment consists of lipid cells which are densely filled with triglyceride droplets, as revealed by thin layer chromatography. Lipid cells are already present in the 1st instar before the nymphs have taken up any food. In later instars, the renal lipid content varies to some extent with the nutritional state and is nearly depleted during metamorphosis. The proximal segment is the region of tubular branching and may be conceived as the collecting duct of each tuft. Its epithelium consists of mucocytes.  相似文献   

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The lectotype ofFavreina salevensis (Paréjas) is re-examined and illustrated and the following new favreine form-species proposed:Favreina guinchoensis from the Upper Jurassic of Portugal,Favreina njegosensis andFavreina dinarica from the Neocomian of the Dinarids, andFavreina eiggensis from the Bathonian of the Inner Hebrides, Scotland.Favreina murciensis Cuvillier, Bassoulet & Fourcade is recorded from the Jurassic of Pakistan.  相似文献   

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A total of 842 white sea bream (Diplodus sargus), sampled in Banyuls-sur-Mer, were analysed to test 'genotype-phenotype' relationship for various characters related to the fitness. The results show significant differences (MLH and FIS) for the age according to the sex between females carrying out and not carrying out sexual inversion. This suggests an overdominance for old females and a genetic sex determination. The individuals laying very early during the period of reproduction are also differentiated from the individuals reproducing later in the season. These results suggest either a stable calendar of laying in time separating the individuals genetically reproducing precociously from the others and this by differential selection and/or genetic drift either a Wahlund effect among cohorts.  相似文献   

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The abundance and aggregation of eggs of Aedes aegypti L. and Aedes albopictus Skuse was evaluated in the municipalities of Cambé, Ibipor?, Jacarezinho, Maringá and Paranavaí, in the State of Paraná, Brazil by means of oviposition traps. Of the 225 installed traps, 100 were registered as positive for eggs; 4140 eggs were collected, thus demonstrating an highly aggregate distribution. Both species were registered in Cambé, Jacarezinho, Maringá and Paranavaí. Ae. albopictus was generally less abundant and was not present in Ibipor? nor in the oviposition traps of a second collection of Maringá. The relation between sexes for Ae. aegypti was approximately 1:1. In the comparison of the number of adults collected between the two species, a negative correlation was obtained in the samples of Maringá and Cambé, what was attributed the seasonality of these populations. The coexistence of these species indicates that both are under pressure by the control programs, therefore specific evaluations are necessary.  相似文献   

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Summary

The life cycle of the Batrachospermales (freshwater florideophyte red such as Batrachospermum, Lemanea) is a shortened variant of the ‘normal’ marine florideophyte life cycle. The perennial Chantransia diploid phase is microscopic and encrusting. Each winter it produces one or more semi-erect haploid gametophytes by vegetative meiosis. Gamete production and fertilization is followed by production of diploid carposporophytes; these produce diploid carpospores which disperse, and regenerate the Chantransia phase. The question of the extent to which the Chantransia phase contributes resources to the gametophyte was approached by physiological-hydrodynamic modelling. These computations suggest that the photosynthetic rates in situ on an area basis are 20 times greater for the gametophyte than the Chantransia phase; this agrees with the observed ratios of peak biomass. The conclusion is that the Chantransia phase has a negligible role in provisioning the growing gametophyte, and that the role of the Chantransia phase is to occupy space with living biomass throughout the year, including exposure at summer drawdown, and (perhaps) by dispersal via production of monospores. A similar conclusion is arrived at on the basis of biomass data for the role of the perennial ‘mushroom’ phase of the semelparous marine Fucalean brown alga Himanthalia elongata in relation to the short-lived but much larger reproductive receptacles.  相似文献   

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The adult of Macrelmis pubescens (Grouvelle, 1889) is redescribed, illustrated, a lectotype designated, and new locality information provided. The lectotype is housed in the Grouvelle’s collection in the Muséum national d’Histoire naturelle, Paris, France. The larva of M. pubescens is described, illustrated and compared with the known larvae of the genus. A diagnosis for Macrelmis Motschulsky, 1860 larvae is provided.  相似文献   

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The fossil remains of two species of Suoidea (Artiodactyla, Mammalia) from the Early/Middle Miocene locality of Sandelzhausen (MN5; Bavaria, Germany) are described. A skull and some isolated teeth and bones reveal hitherto unknown features of Schizoporcus muenzenbergensis, Schizoporcini, Taucanaminae, Palaeochoeridae (Old World peccaries), Suoidea. The phylogeny of the Taucanaminae is discussed and an updated classification of the Palaeochoeridae is presented. The new names Schizoporcus and Schizoporcini replace the junior homonyms Schizochoerus Crusafont and Lavocat (1954) and Schizochoerini Golpe-Posse (1974). Remains of several skulls and mandibles, over 50 associated tooth rows, over 300 isolated teeth, and over 200 bones, constitute one of the largest collections of a Miocene suid known, and are assigned to Hyotherium soemmeringi wylensis, Hyotheriini, Hyotheriinae, Suidae (pigs), Suoidea. Hyotherium is the oldest certain suid genus known and many assumed it to be one of the most primitive. While the postcranial bones of the Suidae and Palaeochoeridae differ in many ways, the bones of Hyotherium are already very similar in morphology to those of living pigs, although they are much more slender, suggesting that the genus was more fleet-footed. Features related to rooting behaviour indicate that Hyotherium was a more efficient rooter than Palaeochoeridae and living Dicotylidae, but not as efficient as living suids. The phylogeny of the Hyotheriinae is discussed. The subfamily is divided into Hyotheriini and Aureliachoerini, new tribe, and an updated classification is presented.  相似文献   

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Entomological Review - A new species Dyscritulus dzhungaricussp. n. from Kazakhstan is described. It is closely related to D. pygmaeus Mackauer, 1961, diff ering from it in the propodeum with 2...  相似文献   

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Pharyngodon medinae García-Calvente, 1948 (Nematoda: Pharyngodonidae) is redescribed from Podarcis pityusensis (Bosca, 1883) (Sauria: Lacertidae) of the Balearic Islands (Spain) and confirmed as a member of the genus Skrjabinodon Inglis, 1968. A systematic review of S. medinae and closely related species is also given. Parathelandros canariensis is referred to Skrjabinodon as a new combination and Parathelandros Magzoub et al., 1980 is dismissed as a junior homonym of Parathelandros Baylis, 1930.  相似文献   

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Surf zones are crucial habitats for many fish species, where they spend the initial stages of their lives, finding food and shelter. One such species is the pompano (Trachinotus ovatus). The aim of this study was to examine the age and diet of the pompano within the surf zone, along with any potential variations in the environment. The average size of the specimens was 10.61 ± 4.91 cm. The length–weight relationship was total weight (TW) = 0.0136*total length (TL)2.8512 (parameter a: 95% C.I. : 0.0130–0.0142 and parameter b: 95% C.I. : 2.8318–2.8705). The most abundant age classes were 0+ and 1+, making up 97% of the captured specimens, with significant differences in the abundance of age classes depending on the time of the day and season. The pompano primarily fed on clupeiforms, copepods, and mysids, with significant variations in diet based on the time of the day, season, and size of the specimens. This study contributes new information about the use of the surf zone by T. ovatus in its early years of life, underscoring the importance of these areas and their role as an additional ecosystem service.  相似文献   

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Five species are included in the Simulium siolii group, which is placed in the subgenus Psaroniocompsa (Diptera: Simuliidae). Of these five species, only two (Simulium siolii Py-Daniel and Simulium tergospinosum Hamada) have been described in all their life stages, except eggs. Knowledge of the taxonomic characters of all life stages of a species is important in order to clarify interspecific and higher-level taxonomic relationships. The objectives of the present study are to describe the male of Simulium damascenoi Py-Daniel, to provide a list of black-fly species their bionomics and distributions in the state of Amap , Brazil, and to provide an identification key for larvae and pupae for these species.  相似文献   

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A revised checklist of the Scathophagidae, Fanniidae and Muscidae recorded from Finland is presented. Phaonia amicula Villeneuve, 1922 is noted from Finland for the first time.  相似文献   

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This study provides comprehensive documentation of silk production in the pest moth Helicoverpa armigera from gland secretion to extrusion of silk thread. The structure of the silk glands, accessory structures and extrusion apparatus are reported. The general schema of the paired silk glands follows that found for Lepidoptera. Morphology of the duct, silk press, muscle attachments and spigot are presented as a three-dimensional reconstruction and the cuticular crescent-shaped profile of the silk press is demonstrated in both open and closed forms with attendant muscle blocks, allowing advances in our knowledge of how the silk press functions to regulate the extrusion of silk. Growth of the spigot across instars is documented showing a distinctive developmental pattern for this extrusion device. Its shape and structure are related to use and load-bearing activity.  相似文献   

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Detailed electrostatic potential (ESP) analyses were performed to compare the directionality of halogen bonds with those of hydrogen bonds and lithium bonds. To do this, the interactions of HOOOH with the molecules XF (X?=?Cl, Br, H, Li) were investigated. For each molecule, the percentage of the van der Waals (vdW) molecular surface that intersected with the ESP surface was used to roughly quantify the directionality of the halogen/hydrogen/lithium bond associated with the molecule. The size of the region of intersection was found to increase in the following order: ClF?<?BrF?<?HF?<?LiF. The maximum ESP in the region of intersection, V S, max, was observed to become more positive according to the sequence ClF?<?BrF?<?HF?<?LiF. For ClF and BrF, the positive electrostatic potential was concentrated in a very small region of the vdW molecular surface. On the other hand, for HF and LiF, the positive electrostatic potential was more diffusely scattered across the vdW surface than for ClF and BrF. Also, the optimized geometries of the dipolymers HOOOH···?XF (X?=?Cl, Br, H, Li) indicated that halogen bonds are more directional than hydrogen bonds and lithium bonds, consistent with the results of ESP analyses.
Graphical abstract Electrostatic potential (ESP) contour maps in the xz plane of ClF and BrF
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A phylogenetic analysis of the early branching lineages of the monocotyledons is performed using data from two plastid genes (rbcL and matK), five mitochondrial genes (atp1, ccmB, cob, mttB and nad5) and morphology. The complete matrix includes 93 terminals representing Acorus, the 14 families currently recognized within Alismatales, and numerous lineages of monocotyledons and other angiosperms. Total evidence analysis results in an almost completely resolved strict consensus tree, but all data partitions, genomic as well as morphological, are incongruent. The effects of RNA editing and potentially processed paralogous sequences are explored and discussed. Despite a decrease in incongruence length differences after exclusion of edited sites, the major data partitions remain significantly incongruent. The 14 families of Alismatales are all found to be monophyletic, but Acorus is found to be included in Alismatales rather than being the sister group to all other monocotyledons. The placement is strongly supported by the mitochondrial data, atp1 in particular, but it cannot be explained as an artifact caused by patterns of editing or by sampling of processed paralogues.  相似文献   

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