首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Adult Taeniopteryx nebulosa (Linnaeus, 1758 Linnaeus, C. (1758), Systema Naturae (10th ed.), Tom 1, Holmiae. [Google Scholar]) and Perlodes microcephalus (Pictet, 1833 Pictet, J., (1833), ‘Memoire sur la Metamorphoses des Perles’, Annales des Sciences Naturelles, XXVII, 4455. [Google Scholar]) emerge late winter to early spring in Danish streams. Based on 13 years of study, we have provided new data and discussed little-known aspects of biology of these two species. Taeniopteryx nebulosa male deposits a spermatophore on the female gonopore. Both species are poor fliers and seek high posts for take-off, where they thermoregulate by basking in a pre-flight sun posture for heating flight muscles. Oviposition flight is erratic and short. The females skim back to land. Taeniopteryx nebulosa eggs drift a long distance as single eggs before adhering to vegetation. Perlodes microcephalus eggs drift a short distance as intact eggpackets before they fasten and disintegrate on the bottom. Perlodes microcephalus females select oviposition sites on or close to upstream a riffle. This is critical in ensuring that eggs fasten on stable gravel and stone bottoms. The fast recolonisation of P. microcephalus in Danish streams following restoration measures indicates efficient dispersal ability despite poor flight performance. Adults of both species adhere to clothes, feather and fur. Taeniopteryx nebulosa tarsomeres have many hooked setae, P. microcephalus tarsomeres have some hooked setae and a dense cover of microtrichia. They may disperse by hitchhiking on birds and mammals.  相似文献   

2.
A short review of main cytogenetic features of insects belonging to the sister neuropteran families Myrmeleontidae (antlions) and Ascalaphidae (owlflies) is presented, with a particular focus on their chromosome numbers and sex chromosome systems. Diploid male chromosome numbers are listed for 37 species, 21 genera from 9 subfamilies of the antlions as well as for seven species and five genera of the owlfly subfamily Ascalaphinae. The list includes data on five species whose karyotypes were studied in the present work. It is shown here that antlions and owlflies share a simple sex chromosome system XY/XX; a similar range of chromosome numbers, 2n = 14-26 and 2n = 18-22 respectively; and a peculiar distant pairing of sex chromosomes in male meiosis. Usually the karyotype is particularly stable within a genus but there are some exceptions in both families (in the genera Palpares and Libelloides respectively). The Myrmeleontidae and Ascalaphidae differ in their modal chromosome numbers. Most antlions exhibit 2n = 14 and 16, and Palparinae are the only subfamily characterized by higher numbers, 2n = 22, 24, and 26. The higher numbers, 2n = 20 and 22, are also found in owlflies. Since the Palparinae represent a basal phylogenetic lineage of the Myrmeleontidae, it is hypothesized that higher chromosome numbers are ancestral for antlions and were inherited from the common ancestor of Myrmeleontidae + Ascalaphidae. They were preserved in the Palparinae (Myrmeleontidae), but changed via chromosomal fusions toward lower numbers in other subfamilies.  相似文献   

3.
Entomological Review - The type and other extensive material of Coprophilus (Zonyptilus) pennifer (Motschulsky, 1845) and some of its synonyms was examined. Coprophilus (Zonyptilus) marginalis...  相似文献   

4.
The complexes cis-diamminebis-cholylglycinate (O,O') [Pt(II) C(52)H(90)N(4)O(12)Pt, for convenience referred to as Bamet-R1] and cis-diamminebis-ursodeoxycholate (O,O') Pt(II) (C(48)H(84)N(2)O(8)Pt, Bamet-UD2) were prepared. The structural integrity of the compounds was confirmed by elemental analysis, FT-IR, NMR, FAB-MS, and UV spectroscopies. The kinetic study of both compounds was accomplished by combining the conductivity measurement and those of the analysis of the electronic spectra in aqueous solution for NaCl concentrations of 4 mM (similar to cytoplasmatic concentration), 150 mM (similar to plasmatic concentration), and 500 mM. In water, the compound Bamet-R1 showed a half-life, t(1/2), of 3.0 h. This compound forms the chelate species through loss of a ligand, and the other one acts as a bidentate ligand. Ring opening in the presence of chloride ion was produced with a k(Cl)()-of 0.25 M(-)(1) h(-)(1). The half-life of Bamet-UD2 in aqueous solution was 3.2 h. However, since this species is not able to chelate and has a lower degree of solubility in the presence of chloride ion, its kinetic behavior was very different from that of the other compound. We consider this to be of great interest with regards to its cytostatic activity. All kinetic measurements were performed under pseudo-first-order conditions, and a pseudo-first-order behavior was found. The antitumoral effect of Bamet-UD2 on several cell lines derived from rat hepatoma, human hepatoma, mouse leukemia, and human colon carcinoma was found to be, in general, similar to that of cisplatin, but higher than that observed for Bamet-R1.  相似文献   

5.
ABO, rhesus and Kell blood group data on 1327 donors in Kabul are analysed by ethnic affinity and compared with existing data on Afghanistan peoples. Blood group frequencies are very similar in Pushtu and Tadjik, despite their different historical, linguistic, and cultural backgrounds. Inclusion of the small sample of Hazara in the analysis shows overall heterogeneity in rhesus D, E, and e frequencies, suggesting the existence of a broader pattern of genetic variation among the peoples of Afghanistan.  相似文献   

6.
7.
Spermiogenesis of the syncarid Anaspides tasmaniae (subclass Eumalacostraca) was investigated by transmission electron microscopy. The spermatozoan of Anaspides is an ovoid cell with an acrosome covering the anterior pole and a lobulated nucleus and mitochondria occupying the rest of the cell. A long subacrosomal filament bypasses the nucleus and forms a spiral that supports a thin extension of the posterior cytoplasm, giving the spermatozoan a bell-shaped appearance. No flagellum is present at any stage. The immobile spermatozoans are embedded in a hard capsule, secreted by the cells of the wall of the vas deferens.  相似文献   

8.
9.
The coremata and male genital structures together with the associated muscles of Zygaena trifolii are described and illustrated in detail. Of the female genitalia only the external parts are dealt with. The closure of the male coremata pouch was found to be effected by a special muscle. Mating pairs were quickly fixed while in copula and dissected afterwards in order to examine the mechanism of copulation. It turns out that the female is held by the male at three points: first, the gonopods (= valvae) grip the female abdominal tip laterally. Secondly, the praephallus together with the everted endotheca (= vesica) are tightly locked inside the female ductus bursae. Thirdly, female postvaginal structures become evaginated and are then held between the spined anellus and the eighth abdominal tergum of the male.  相似文献   

10.
11.
Squamation and scale morphology provide interesting characters for phyletic analysis within the Cichlidae. It is not known, however, to what extent these characters are genetically fixed or determined by environmental parameters. To clarify this point, a study on Sarotherodon galilaeus was conducted. This species has an extensive distribution and lives in markedly different environments. Most scale characters were found to be remarkably stable within the species. The only large variations occur in scale counts, extent of caudal fin Squamation, number of circuli and radii, and the extent of scale granulation. The Squamation pattern, the form of the circuli and radii, the shape of interradial rostrad projecting tongues, the denticles on the circuli in the rostral field, and especially the kind of granulation in the caudal field is similar in all specimens examined and is also retained in fish bred in aquaria for several generations. Thus it seems justified to assume that these characters are strongly determined by genetic factors and that their analysis can be useful in the determination of phyletic relationships.  相似文献   

12.
Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC50 = 292.17 ± 27.71 μM and 331.94 ± 21.21 μM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC50 = 275.24 ± 13.15 μM). These values are significantly lower than those of ascorbic acid (EC50 = 1129.32 ± 88.79 μM) and α-tocopherol (EC50 = 944.62 ± 148.00 μM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68 ± 0.27; synthetic (S,S)-SDG-1: 2.09 ± 0.16; synthetic (R,R)-SDG-2: 1.96 ± 0.27], peroxyl [natural (S,S)-SDG-1: 2.55 ± 0.11; synthetic (S,S)-SDG-1: 2.20 ± 0.10; synthetic (R,R)-SDG-2: 3.03 ± 0.04] and DPPH [natural (S,S)-SDG-1: EC50 = 83.94 ± 2.80 μM; synthetic (S,S)-SDG-1: EC50 = 157.54 ± 21.30 μM; synthetic (R,R)-SDG-2: EC50 = 123.63 ± 8.67 μM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.  相似文献   

13.
The floodwater mosquito Aedes vexans can be a massive nuisance in the flood plain areas of mainland Europe, and is the vector of Tahyna virus and a potential vector of Dirofilaria immitis. This epidemiologically important species forms three subspecies worldwide, of which Aedes vexans arabiensis has a wide distribution in Europe and Africa. We quantified the genetic and phenotypic variation in Ae. vexans arabiensis in populations from Sweden (northern Europe), Hungary, and Serbia (central Europe). A landscape genetics approach (FST, STRUCTURE, BAPS, GENELAND) revealed significant differentiation between northern and southern populations. Similar to genetic data, wing geometric morphometrics revealed two different clusters, one made by Swedish populations, while another included Hungarian and Serbian populations. Moreover, integrated genetic and morphometric data from the spatial analysis suggested groupings of populations into three clusters, one of which was from Swedish and Hungarian populations. Data on spatial analysis regarding an intermediate status of the Hungarian population was supported by observed Isolation‐by‐Distance patterns. Furthermore, a low proportion of interpopulation vs intrapopulation variance revealed by AMOVA and low‐to‐moderate FST values on a broader geographical scale indicate a continuous between‐population exchange of individuals, including considerable gene flow on the regional scale, are likely to be responsible for the maintenance of the observed population similarity in Aе. vexans. We discussed data considering population structure in the light of vector control strategies of the mosquito from public health importance.  相似文献   

14.
Two species of coastal flatfish (brill and turbot, Scophthalmidae) were analysed electrophoretically at 17 common enzymatic loci in samples taken from 11 sites representing the species ranges in Europe. Brill showed a mean heterozygosity ( H ) of 0·11 while that of turbot was 0·02. The virtual absence of genetic diversity in turbot is probably due to a very low evolutionary rate, and provides little evidence for population substructure even if various signs indicate the possibility of a hidden differentiation (presence of the taxon maoetica in the Black Sea and differentiation of a species-specific cestode parasite on either side of the Strait of Gibraltar). On the other hand, the weak geographic structure in brill seems to result from rapid recolonization following the last ice age.  相似文献   

15.
Adult specimens of Cochliomyia macellaria, Chrysomya megacephala, Ch. rufifacies, Lucilia sp. (Calliphoridae), Musca domestica (Muscidae), Oxelytrum discicolle (Silphidae) and Sarcophagidae were recovered from 12 human cadavers in Cali, Valle, Colombia. Information regarding these findings is presented.  相似文献   

16.
17.
18.
Variations of shell form and shell length were studied for oysters growing in the mangroves of Gazi Creek, Kenya, and related to different environmental factors.For the study of the form, Fourier analysis was performed on the circumference of 85 oysters. The resulting coefficients were compared among specimens using cluster analysis. The correspondence between this classification and substrate diameter is virtually perfect (only one misclassification out of 85 oysters). For the clusters based on height above chart datum, 9 specimens, all on intermediate height levels, were misclassified. Orientation with respect to tidal current had 13 misclassifications. Mangrove species seemed to influence form only marginally, if at all.In the study of the size ofCrassostrea cucullata, the length of 956 oysters, growing along two transects were measured, and correlated with several environmental factors. Oyster length was not related to substrate diameter or its orientation with respect to the main current. Length was not influenced by density up to a cover of 70%. For densities higher than 70%, there was a fairly strong negative correlation (r 2 = 0.634,n = 217). Length was not correlated with height above bottom (base of the tree) for heights lower than 20 cm, while oysters growing closer to the bottom were smaller. The correlation with height above chart datum was negative but very low (r 2 = 0.060,n = 957). However, if all measurements of oysters closer than 20 cm to the bottom, and all from a density of more than 70% cover are deleted from the data set, the correlation with height increased dramatically, the slope still being negative (r 2 = 0.859,n = 543).  相似文献   

19.
An antidiuretic mechanism is proposed for Rhodnius prolixus, whose activity is manifested when the diuretic phase has terminated and is maintained until the insect has fed again. Presumably this mechanism acts at the level of the proximal rectal sphincter and is inhibited by ingestion, mechanical distension of the gut and central disinhibition by decapitation. It is suggested that the antidiuretic activity is maintained by the nervous system and is modified when there is distention of the gut or when the nervous signal is interrupted by decapitation. It is demonstrated that the excretion of urine in R. prolixus is not controlled exclusively by the diuretic hormone, but rather that factors not linked to the haemolymph maintain the insects in a diuretic or nondiuretic state.  相似文献   

20.
In order to investigate the relationship existing between the electronic structures of collagen and its biochemical functions in vivo, the semiempirical CNDO/2 SCF MO calculations were carried out on several model polymers of collagen, (Gly-Pro)n, (Gly-Hyp)n, (Ala-Pro)n, (Ala-Hyp)n, (Gly-Pro-Gly)n, (Gly-Hyp-Gly)n, (Gly-Pro-Pro)n and (Gly-Pro-Hyp)n. Geometries of the skeleton of these polymers were assumed to be the same as those of poly(l-proline) I (cis) and II (trans) and the calculations were performed only on infinite polymers in a single chain. The results show that the cis form is always more stable than the trans form for all the polymers treated. This energy difference between the cis and trans forms depends, for example, on the kind of amino acid residue, Gly or Ala, but this could not be seen in the Pro or Hyp residue. The flexibility or mobility of the collagen structure was explained using the energy difference between the cis and trans forms of the polymers, i.e. the cis-trans conversion of the collagen was discussed in connection with the energy difference. The reason why the collagen has the constitution of (Gly-Pro-Hyp)n is briefly discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号