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1.
Pseudotettigonia leona sp.n. is described from a single left forewing collected from the Middle Eocene Kishenehn Formation in northwestern Montana, U.S.A. P. leona is the second of only two fossil macropterous Tettigoniidae that preserve an intact stridulatory apparatus. The subfamily Pseudotettigoniinae is reexamined. The specific epithet bricei is assigned to the late Miocene fossil tettigoniid Tettigonia bricei sp.n. , originally described as the extant Tettigonia viridissima. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:E69E83CE‐9046‐4BBD‐AA11‐E0AD0C382700 . 相似文献
2.
Abstract Using the method of compartmental analysis, the ion fluxes and compartment concentrations of Ca2+, K+ and Cl- have been compared in the untreated vegetative frond and the abscisic acid (ABA) induced turion of Spirodela polyrrhiza. The ABA-induced turion is characterized by reduced Ca2+ exchange across the tonoplast and low vacuolar Ca2+ concentration relative to the vegetative frond. In addition the turion exhibits a higher plasmalemma flux with a correspondingly high Ca2+ concentration in the cytoplasm. The concentration of K+ and Cl- is much lower in the cytoplasm of the ABA-induced turion than in the vegetative frond with the influx/efflux ratio at both the plasmalemma and the tonoplast being less than 1, a finding exhibited also in dormant storage tissue. Treatment of vegetative fronds with ABA for 18 h resulted in a reduced K+ plasmalemma efflux relative to untreated vegetative fronds and a concomitant increase in the cytoplasmic concentration. There was no rapid effect of ABA on Ca2+, K+ or Cl- fluxes through either membrane. These results are consistent with the notion that drastic changes in ion fluxes and concentrations in the turion are a secondary consequence of ABA-induced development, possibly due to prior regulation by ABA of enzymes inherent to processes involved in membrane transport. 相似文献
3.
CHERYL D. WILGA PETER C. WAINWRIGHT PHILIP J. MOTTA 《Biological journal of the Linnean Society. Linnean Society of London》2000,71(1):165-185
The widely accepted phylogenctic position of Chondrichthyes as the sister group to all other living gnathostomes makes biomechanical analyses of this group of special significance for estimates of skull function in early jawed vertebrates. We review key findings of recent experimental research on the feeding mechanisms of living elasmobranchs with respect to our understanding of jaw depression mechanisms in gnathostome vertebrates. We introduce the possibility that the ancestral jaw depression mechanism in gnathostomes was mediated by the coracomandibularis muscle and that for hyoid depression by the coracohyoideus muscle, as in modern Chondrichthyes and possibly placoderms. This mechanism of jaw depression appears to have been replaced by the sternohyoideus (homologous to the coracohyoideus) coupling in Osteichthycs following the split of this lineage from Chondrichthyes. Concurrent with the replacement of the branchiomandibularis (homologous to the coracomandibularis) coupling by the sternohyoideus coupling as the dominant mechanism of jaw depression in Osteichthyes was the fusion and shift in attachment of the intcrhyoideus and intermandibularis muscles (producing the protractor hyoideus muscle, mistakenly refereed to as the geniohyoideus), which resulted in a more diversified role of the sternohyoideus coupling in Osteichthyes. The coracohyoideus coupling appears to have been already present in vertebrates where it functioned in hyoid depression, as in modern Chondrichthyes, before it acquired the additional role of jaw depression in Osteichthyes. 相似文献
4.
Abstract The developmental process leading to the formation of the abscisic acid (ABA) induced turion of Spirodela polyrrhiza was accompanied by a repression of nucleic acid and protein synthesis. DNA synthesis in the developing lurion (induced by 10−4mol m−3 ABA) was inhibited within 3h of ABA addition, followed by a repression of protein synthesis after 24 h, while RNA synthesis was not inhibited until 3 d. The inhibitory effect of ABA on protein synthesis was found to be selective and the synthesis of several novel proteins appeared to be induced. These effects were specific to ABA-sensitive tissue. The relationship between the changes in the protein and mRNA profiles during the development of the turion was investigated. The rapid general inhibition of protein synthesis at early stages of lurion formation could not be accounted for by the level of translatable mRNA, indicating an effect of ABA at the translational level. The specific alteration to the pattern of in vivo labelled proteins could have resulted, however, from control of the level of specific mRNAs for those particular proteins. Only after 3 d in ABA, when the developing primordium is committed to the turion developmental pathway, is there a total inhibition in the production of mRNA leading to the shutdown of all primary processes and the onset of the irreversible events leading to the dormant state. 相似文献
5.
HANS RUDOLF KOBEL MARIANNE EGENS DE SASSO CHERYL ZLOTOWSKI 《Differentiation; research in biological diversity》1979,14(1-3):51-58
Diploid as well as triploid Xenopus interspecific hybrids generate aneuploid eggs because of the presence, at meiosis, of univalent chromosomes which are presumably distributed at random. Zygotes obtained from such eggs, fertilized by either normal or UV-irradiated sperm, were analysed for their developmental capacities. All monosomics die in the course of embryogenesis, whereby optimum capacities correspond closely with those observed in monosomic mammalian embryos, especially in mice. In contrast, hyperdiploid Xenopus are relatively viable: although many die exhibiting the'haploid syndrome'or various other abnormalities, 8% of them reach metamorphosis, and 1–2% become adults. Of the latter, the karyotype was established in 13 individuals. Among them, 8–16 supernumerary chromosomes were found to be present. 相似文献
6.
Relative Contributions of Urine and Anal-Sac Secretions in Scent Marks of Large Felids 总被引:1,自引:0,他引:1
SYNOPSIS. A hypothesis generated from field observations oflions and tigers was tested in a zoo setting. The presence ofa whitish material in urine marks, detected by visual inspection,led to the surmise that analsac secretions were expelled alongwith urine. This hypothesis was evaluated by labelling anal-sacsecretions of various felids with an inert dye. The animalswere monitored thereafter for signs of dye in urine-marks, onfeces or in their enclosures. The failure to find anal-sac secretionsin urine or on feces led to a search for an alternate explanationfor the whitish material. A likely answer was found in the confirmationof considerable lipid in the bladder urine of lions and tigers,which separates to form a visible, whitish layer. Relative levelsof urinary lipid reflect general condition of an animal as theycorrelate with kidney fat reserves (Hewer et al., 1948), sothe amount of lipid in a scent mark could serve as an indicatorof condition. Furthermore, because lipid retards the releaseof volatile compounds (Regnier and Goodwin, 1976), lipid ina scent mark will extend release time of a pheromonal message. 相似文献
7.
1. Polyembryonic parasitoid wasps in the family Encyrtidae (Hymenoptera) have evolved a caste system consisting of morphologically and functionally distinct larvae called soldiers and reproductives. 2. Two selective pressures are thought to underlie the evolution of the soldier caste: defence against competitors and resolution of the sex ratio conflict. Previous studies also indicate that soldier development time strongly affects the outcome of intra‐specific competition in the polyembryonic encyrtid Copidosoma floridanum Ashmead. This study builds on prior findings by showing that alleles of the metabolic enzyme phosphoglucose isomerase (Pgi) differentially affect soldier development time and the outcome of competition. 3. Soldier larvae with the Pgi alleles 100 or 120 emerged on average 65 h post‐parasitism, whereas soldier larvae with a third allele, 54, emerged at 67 h. In turn, C. floridanum broods homozygous for the 100 and 120 alleles outcompete broods homozygous for the 54 allele. 4. Pgi allelic diversity may be maintained through a life‐history trade‐off affecting female brood sizes with homozygous broods bearing the developmentally disadvantageous 54 allele producing more adult females than broods bearing alternate common alleles. 相似文献
8.
A functional analysis of jaw suspension in elasmobranchs 总被引:3,自引:0,他引:3
9.
Canid Reproductive Biology: an Integration of Proximate Mechanisms and Ultimate Causes 总被引:2,自引:0,他引:2
SYNOPSIS. The canid reproductive system includes many featuresthat are unusual or even unique among mammals. Focusing on graywolves, for example, these include monogamy, monestrum withexceptionally long proestrous and diestrous phases, a copulatorylock or tie, incorporation of adult young into the social group,behavioral suppression of mating in these subordinate young,obligate pseudopregnancy in subordinate females, and alloparentalcare. These features can be analyzed on the levels of both proximateand ultimate causation by considering them in the context ofthe reproductive system as a whole. First, when assessing possibleproximate mechanisms, monestrum appears to be pivotal. It isprobably accomplished by the extremely long luteal or diestrousphase, which is followed by a seasonal peak in prolactin. Twosequellae of the extended diestrus (or pseudopregnancy) in non-pregnantsubordinate females are to 1) suppress any subsequent cycles,and 2) hormonally prime them to behave maternally. The prolactinpeak in all adult pack members, coincident with the birth ofpups, also may stimulate parental behavior. The risk of monestrum(limited chance for conception) appears to be reduced by therelatively long proestrous and estrous periods, as well as bymonogamy. The adaptive value, or ultimate cause, of this reproductivesystem is most obvious for the more social canid species, suchas the gray wolf. That is, advantages to sociality, such ascooperative hunting, may have driven development of the anomaliesof the reproductive system. 相似文献
10.
Social Modulation of Circulating Hormone Levels in the Male 总被引:3,自引:1,他引:2
SYNOPSIS. In many species, social interactions rapidly modulatecirculating hormone levels in the male. Sexual interaction ormere exposure to a conspecific female results in rapid, transientelevation of both plasma luteinizing hormone and testosteroneconcentrations in a variety of species. In contrast, aggressiveinteractions result in decreased plasma gonadotropin and testosteronelevels and increased levels of adrenal corticoids. In general,these changes are more profound and of longer duration thanthose accompanying sexual interactions, particularly among subordinatemales. These fluctuations in circulating hormone levels appearto be related to an individual's behavioral responsivity. Forexample, plasma concentrations of luteinizing hormone duringa social encounter are positively correlated with the degreeof sexual arousal shown by a male during the interaction. Similarcorrelations have been found between plasma androgen or corticoidlevels and patterns of behavior shown by males during both sexualand aggressive interactions. The causal relationship betweensuch rapid hormone fluctuations and behavior remains unclear.Are fluctuating hormone levels causing differences in behavioror aredifferent patterns of behavior causing differences inplasma hormone levels between males? Or is the correlation betweenthese two variables caused by their relationship to anotherunidentified factor? There are some data favoring the firstpossibility. Increasing the magnitude of socially induced hormonefluctuations during an aggressive encounter or preventingsuchfluctuations entirely significantly alters an animal's behavior.These data suggest that the endocrine system may play a moreimportant role in an individual's minute-to-minute responseto critical social stimuli than was previously realized. 相似文献