Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character最新文献

{"title":"Why do morphological phylogenies vary in quality? An investigation based on the comparative history of lizard clades.","authors":"E N Arnold","doi":"10.1098/rspb.1990.0031","DOIUrl":"https://doi.org/10.1098/rspb.1990.0031","url":null,"abstract":"<p><p>Phylogenies based on morphology vary considerably in their quality: some are robust and explicit with little conflict in the data set, whereas others are far more tenuous, with much conflict and many possible alternatives. The main primary reasons for untrue or inexplicit morphological phylogenies are: not enough characters developed between branching points, uncertain character polarity, poorly differentiated character states, homoplasy caused by parallelism or reversal, and extinction, which may remove species entirely from consideration and can make originally conflicting data sets misleadingly compatible, increasing congruence at the expense of truth. Extinction differs from other confounding factors in not being apparent either in the data set or in subsequent analysis. One possibility is that variation in the quality of morphological phylogenies has resulted from exposure to different ecological situations. To investigate this, it is necessary to compare the histories of the clades concerned. In the case of explicit morphological phylogenies, ecological and behavioural data can be integrated with them and it may then be possible to decide whether morphological characters are likely to have been elicited by the environments through which the clade has passed. The credibility of such results depends not only on the phylogeny being robust but also on its detailed topology: a pectinate phylogeny will often allow more certain and more explicit statements to be made about historical events. In the case of poor phylogenies, it is not possible to produce detailed histories, but they can be compared with robust phylogenies in the range of ecological situations occupied, and whether they occupy novel situations in comparison with their outgroups. LeQuesne testing can give information about niche homoplasy, and it may also be possible to see if morphological features are functionally associated with ecological parameters, even if the direction of change is unknown. Examination of the robust and explicit phylogeny of the semaphore geckoes (Pristurus) suggests that its quality does stem from a variety of environmental factors. The group has progressed along an ecological continuum, passing through a series of increasingly severe niches that appear to have elicited many morphological changes. The fact that niches are progressively filled reduces the likelihood of species reinvading a previous one with related character reversal. Because the niches of advanced Pristurus are virtually unique within the Gekkonidae the morphological changes produced are also very rare and therefore easy to polarize. Ecological changes on the main stem of the phylogeny are abrupt and associated character states consequently well differentiated.(ABSTRACT TRUNCATED AT 400 WORDS)</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"240 1297","pages":"135-72"},"PeriodicalIF":0.0,"publicationDate":"1990-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A model of quantitative traits under frequency-dependent balancing selection.","authors":"G S Mani,&nbsp;B C Clarke,&nbsp;P R Shelton","doi":"10.1098/rspb.1990.0024","DOIUrl":"https://doi.org/10.1098/rspb.1990.0024","url":null,"abstract":"<p><p>We describe a computer model that stimulates a combination of stabilizing and frequency-dependent selection acting on a quantitative character determined by several loci. The results correspond to many features of natural variations at both the phenotypic and genotypic levels. The model is robust, and its results are not strongly dependent either on the nature and shape of the function describing the stabilizing selection, or on the precise form of frequency dependence, except near the extrema. It suggests a mechanism for the maintenance of large amounts of variability, and shows a relation between population size and heterozygosity roughly corresponding to that found in nature. In this respect it is unlike the purely neutral model.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"240 1297","pages":"15-28"},"PeriodicalIF":0.0,"publicationDate":"1990-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temporal and spatial correlation of fertilization current, calcium waves and cytoplasmic contraction in eggs of Ciona intestinalis.","authors":"C Brownlee,&nbsp;B Dale","doi":"10.1098/rspb.1990.0019","DOIUrl":"https://doi.org/10.1098/rspb.1990.0019","url":null,"abstract":"<p><p>Eggs of the ascidian Ciona intestinalis were loaded with the calcium indicator fura-2 via whole-cell clamp electrodes and changes in cytoplasmic calcium and cell currents were monitored during fertilization either in separate eggs or simultaneously in the same egg. The first indication of egg activation was the fertilization current; which reached peak values around 1 nA after 30 s. A wave of elevated calcium was detectable between 5 s and 30 s (mean = 21 s) after the start of the fertilization current. This wave spread across the egg increasing cytoplasmic calcium levels to at least 10 microM. When the fertilization current and calcium wave were complete and cytoplasmic calcium levels were decreasing to prefertilization levels, a cortical contraction wave spread across the egg surface. In eggs showing normal fertilization current, the calcium wave and the contraction wave were in the same direction. A region of elevated calcium persisted at the animal pole. Changing cytoplasmic calcium levels locally by local application of ionophore A23187 caused a contraction wave originating at the site of ionophore application. Increasing cytoplasmic calcium uniformly by facilitating calcium entry through voltage-regulated channels did not result in a contraction wave.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"321-8"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probabilistic secretion of quanta from nerve terminals at synaptic sites on muscle cells: non-uniformity, autoinhibition and the binomial hypothesis.","authors":"M R Bennett,&nbsp;J Robinson","doi":"10.1098/rspb.1990.0020","DOIUrl":"https://doi.org/10.1098/rspb.1990.0020","url":null,"abstract":"<p><p>A model of the secretion of a quantum at a release site is proposed in which, following the influx of calcium ions, synaptic vesicles are made available for release by the activation of kappa phosphorylation steps with rate alpha. At any time during this process the vesicles may become unavailable for secretion at rate gamma. On completion of the kappa phosphorylation steps the vesicles participate in the formation of a fusion pore with the terminal membrane to give exocytosis at rate delta. Changes in alpha, delta and kappa are shown to produce characteristic changes in the number and timecourse of quantal secretions following a nerve impulse, which are similar to those observed following drug treatments that are thought to act selectively on each of these processes. The number of quanta secreted from nerve terminals that consist of many release sites does not fluctuate much during a low frequency train of impulses: the variance is small compared with the mean level, so secretion follows binomial rather than Poisson statistics. A theory is derived that shows that variations in the probability of secretion amongst these release sites of any particular kind fails to reduce the variance of the total secretion from the terminal; Poisson rather than binomial statistics then still apply. The theory shows that an interaction between release sites is required to reduce this variance and such an effect is provided if secretion at a site inhibits secretion at nearby sites. Simulations show that incorporating this process of autoinhibition into the model reproduces the experimental observations on the effects of calcium ions on the binomial parameters p and n as well as on the relative constancy of p during facilitation and depression of quantal secretion. Methods for estimating the timecourse of changes in the probability of secretion at release sites following an impulse, by using either the time of occurrence of first, second, third or later quantal latencies, are given. These procedures show that current methods for estimating the time-dependent probability changes are inadequate for detecting interaction between release sites, such as autoinhibition, unless this is relatively large. Therefore, estimates from third quantal latencies are used.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"329-58"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ion-channel properties of mastoparan, a 14-residue peptide from wasp venom, and of MP3, a 12-residue analogue.","authors":"I R Mellor,&nbsp;M S Sansom","doi":"10.1098/rspb.1990.0022","DOIUrl":"https://doi.org/10.1098/rspb.1990.0022","url":null,"abstract":"<p><p>Mastoparan, a 14-residue peptide, has been investigated with respect to its ability to form ion channels in planar lipid bilayers. In the presence of 0.3-3.0 microM mastoparan, two types of activity are seen. Type I activity is characterized by discrete channel openings, exhibiting multiple conductance levels in the range 15-700 pS. Type II activity is characterized by transient increases in bilayer conductance, up to a maximum of about 650 pS. Both type I and type II activities are voltage dependent. Channel activation occurs if the compartment containing mastoparan is held at a positive potential; channel inactivation if the same compartment is held at a negative potential. Channel formation is dependent on ionic strength; channel openings are only observed at KCl concentrations of 0.3 M or above. Furthermore, raising the concentration of KCl to 3.0 M stabilizes the open form of the channel. Mastoparan channels are weakly cation selective, PK/Cl approximately 2. A 12-residue analogue, des-Ile1,Asn2-mastoparan, preferentially forms type I channels. The ion channels formed by these short peptides may be modelled in terms of bundles of transmembrane alpha-helices.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"383-400"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12859252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Texton segregation by associated differences in global and local luminance distribution.","authors":"H C Nothdurft","doi":"10.1098/rspb.1990.0018","DOIUrl":"https://doi.org/10.1098/rspb.1990.0018","url":null,"abstract":"<p><p>Perceptual segregation of visual textures has been attributed to certain features ('textons') such as (elongated) blobs of given size and orientation, line crossings, and line ends. Differences in the spatial distribution of these features were assumed to be detected pre-attentively and to provide the instantaneous impression of segregating texture areas and of borders between them. This paper questions the validity of this general view and, in particular, the role of some of these features in texture discrimination. It is demonstrated that for some textons, perceptual segregation is independent of detection and discrimination of the texton itself. In addition, segregation can be strongly affected by positional or luminance jitter of texture elements or by other modifications that change the luminance distribution in the pattern but do not affect the supposed texton differences. From the textons reported in the literature, only differences in orientation were found to be fairly robust against such modifications.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"295-320"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13316644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size-dependent pigmentation-pattern formation in embryos of Alligator mississippiensis: time of initiation of pattern generation mechanism.","authors":"J D Murray,&nbsp;D C Deeming,&nbsp;M W Ferguson","doi":"10.1098/rspb.1990.0017","DOIUrl":"https://doi.org/10.1098/rspb.1990.0017","url":null,"abstract":"<p><p>The pigmentation pattern of Alligator mississippiensis was examined. The number of white stripes on the dorsal side of embryos (stages 21-28) and hatchlings from eggs incubated at 30 degrees C (100% females) and 33 degrees C (100% males) was recorded. Total length, nape-rump length and tail length were recorded for each embryo and hatchling. The number of white stripes was affected by incubation temperature but not sex; hatchlings incubated at 33 degrees C had two more white stripes than those at 30 degrees C, despite being the same length. Five female hatchlings produced at 33 degrees C by manipulation of the temperature, had the same number of stripes as males that developed under the same incubation temperatures. The appearance of the pigmentation was accelerated in embryos incubated at 33 degrees C, occurring eight days earlier than at 30 degrees C. At the time just before the first signs of pigment deposition, embryos from 33 degrees C were longer than those at 30 degrees C. If the stripe formation is size dependent this explains why hatchlings at 33 degrees C have more stripes than hatchlings from 30 degrees C. The mechanism that produces the stripe patterns is unknown. We describe key elements a pattern formation mechanism must possess to produce such stripes and suggest a possible mechanism, based on cell movement driven by chemotaxis. We apply the mathematical model to dorsal patterning on A. mississippiensis. We show how length at pattern formation is the prime factor in determining stripe number and how the pattern can be formed in the observed anterior-posterior sequence. We present numerical simulations and show that the qualitative behaviour is consistent with the experimental results.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"279-93"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Ferrier lecture, 1989. Outlooks for blindsight: explicit methodologies for implicit processes.","authors":"L Weiskrantz","doi":"10.1098/rspb.1990.0016","DOIUrl":"https://doi.org/10.1098/rspb.1990.0016","url":null,"abstract":"<p><p>In primates the retina is connected with different targets in the brain via several parallel pathways, the largest of which is that going to the lateral geniculate nucleus of the thalamus and thence to the striate cortex, the geniculo-striate pathway. When this route is damaged in man, apparent blindness in a corresponding part of the visual field occurs, despite the integrity of the other parallel pathways. In animals, it has been demonstrated by conventional behavioural forced-choice techniques that extrastriate routes can sustain a variety of visual discriminations. Comparable discriminations are also possible in some human subjects with geniculo-striate damage when forced-choice 'guessing' techniques are used. 'Blind-sight' refers to those subjects who state that they are unaware of the visual stimuli, even when performing discriminations at high levels of proficiency. Extensions of this approach are reviewed, especially to spectral sensitivity and movement discrimination. But residual capacities can also be assessed without requiring guessing responses, thereby avoiding issues of differential response criteria and other practical difficulties. Effects of 'unseen' stimuli in the cortically blind field on the visible perception of concurrent stimuli in the intact field can be measured. Also, positive reactions of the autonomic nervous system, such as the galvanic skin response, can be recorded to visual stimuli presented in the blind field. Recent evidence demonstrates that the pupil in normal adult subjects is systematically sensitive to structural and chromatic features of visual stimuli. Pupillometry reveals specific changes and residual capacities in visual-field defects of adult patients with striate cortical damage. Thus non-verbal and sensitive methods are available that permit the comparative study of normal and residual visual capacity in human infants, adults and infra-human animals.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1296","pages":"247-78"},"PeriodicalIF":0.0,"publicationDate":"1990-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13131138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glycosylation is required for maintenance of functional voltage-activated channels in growing neocortical neurons of the rat.","authors":"C Zona,&nbsp;F Eusebi,&nbsp;R Miledi","doi":"10.1098/rspb.1990.0011","DOIUrl":"https://doi.org/10.1098/rspb.1990.0011","url":null,"abstract":"<p><p>Voltage-activated currents were studied in whole-cell patch-clamped rat neocortical neurons growing in culture and treated with tunicamycin (TU), an inhibitor of protein N-glycosylation. The size of the Na+ current decreased progressively in the presence of TU (1-2 microM). This decrease was faster in growing 5-14 day-old neurons (to ca. 40% of control after 24 hours of treatment) than in fully grown 20-40-day-old neurons (to ca. 40% of control after 68 hours of treatment). The fast transient K+ current (A-current) was abolished, and the delayed rectifier K+ current was markedly reduced by a 24 hour treatment with TU (1-2 microM) in growing neurons. In contrast, in fully grown neurons these currents were unaffected by the same TU treatment. The size of the Ca2+ current was significantly reduced following a 24 hour treatment with TU (1-2 microM) in neurons at early stages of differentiation, but remained stable in 20-40-day-old neurons. It is concluded that protein glycosylation, presumably of the channel proteins themselves, is important for the functional expression of voltage-activated channels in embryonic cortical neurons during the early stages of cell growth in culture; the channels become less dependent on glycosylation in mature neurons.</p>","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1295","pages":"119-27"},"PeriodicalIF":0.0,"publicationDate":"1990-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"12856935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physiology of HI horizontal cells in the primate retina.","authors":"R F Dacheux,&nbsp;E Raviola","doi":"10.1098/rspb.1990.0014","DOIUrl":"https://doi.org/10.1098/rspb.1990.0014","url":null,"abstract":"Two types of recording were obtained from horizontal cells in the superfused eyecup preparation of the retina of Macaca mulatta. Injection of horseradish peroxidase showed that one class of responses was generated by the cell body of H I horizontal cells. The origin of the other type of responses was not identified morphologically, but they were strikingly similar to those recorded from the axonal arborization of axon-bearing horizontal cells of other mammalian species. The soma of H I cells responded with graded hyperpolarizations to increasing changes in diffuse white-light illumination. Threshold responses were obtained with stimulus intensities above electroretinogram (ERG) b-wave threshold; this was taken as an indication of cone input to this part of the cell. Responses to low-intensity stimuli were small, sustained hyperpolarizations; at intermediate intensities, the hyperpolarizations were initiated by a prominent transient component and were followed by a small rod after-effect at stimulus termination; with bright flashes, the transient component was abolished and the rod after-effect became larger. The spectral input of the H I cell body was tested with chromatic stimuli matching the spectral sensitivity of primate cone pigments: responses to all wavelengths were hyperpolarizations. Spectral sensitivity values for the different wavelengths and a comparison of the spectral amplitude–intensity curves for 450 nm, 540 nm and 630 nm wavelengths suggested that H I cell bodies had a non-specific, broad-band sensitivity to mid-spectral wavelengths. Thus more than one spectrally sensitive mechanism was involved in the generation of their response and they were not univariant. This was supported by the morphological observation that the clusters of terminal dendritic branchlets of H I cells had the same arrangement and distance from each other as the overlying cone inner segments, suggesting that these cells contact cones in an indiscriminate fashion. The other class of horizontal cell responses were characterized by a lower threshold, a larger amplitude with low intensity stimuli, a steeper increment in amplitude with increasing intensity, a saturation at moderate levels of illumination and a prominent rod after-effect in response to bright-light stimuli. We concluded that these responses were generated by the axon terminal of H I horizontal cells, that receives synaptic input from rods. Thus H I horizontal cells belong to the luminosity type, are not involved in the processing of colour contrast and are homologous to the axon-bearing horizontal cells of other mammalian retinas.","PeriodicalId":54561,"journal":{"name":"Proceedings of the Royal Society of London Series B-Containing Papers of Abiological Character","volume":"239 1295","pages":"213-30"},"PeriodicalIF":0.0,"publicationDate":"1990-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1098/rspb.1990.0014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13129640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}