天然醛类化合物的存在类型和共存关系

带有醛基的天然化合物,具有苯丙素、萜类、皂苷类、生物碱、香豆素和蒽醌等多个存在的类型。一些植物中存在的多个醛类化合物,往往是带有醛基的母核部分相同,而取代基不同。而在有些植物中,还可以见到一些母核部分相同,而仅仅是醛基的碳呈不同氧化状态的系列化合物,表现为甲基(-CH3)、羟甲基(-CH2OH)、醛基(-CHO)、羧酸基(-COOH)和酯基(-COOR)。     

SULFHYDRYL AND DISULFIDE GROUPS OF PROTEINS : II. THE RELATION BETWEEN NUMBER OFSH AND S-S GROUPS AND QUANTITY OF INSOLUBLE PROTEIN IN DENATURATION AND IN REVERSAL OF DENATURATION

1. In native egg albumin no SH groups are detectable, whereas in completely coagulated albumin as many groups are detectable as are found in the hydrolyzed protein. In egg albumin partially coagulated by heat the soluble fraction contains no detectable groups, and the insoluble fraction contains the number found after hydrolysis. 2. In the reversal of denaturation of serum albumin, when insoluble protein regains its solubility, S-S groups which have been detectable in the denatured protein, disappear. 3. When egg albumin coagulates at an air-water interface, all the SH groups in the molecule become detectable. 4. In egg albumin coagulated by irradiation with ultraviolet light, the same number of SH groups are detectable as in albumin coagulated by a typical denaturing agent. 5. When serum albumin is denatured by urea, there is no evidence that S-S groups appear before the protein loses its solubility. 6. Protein denaturation is a definite chemical reaction: different quantitative methods agree in estimates of the extent of denaturation, and the same changes are observed in the protein when it is denatured by different agents. A protein molecule is either native or denatured. The denaturation of some proteins can be reversed.     

Statistical variation of selected clinical pathological and biochemical measurements in rodents

The variability in clinical pathological and biochemical measurements among replicates is often greater than the effects under study. To minimize the effects of this variability, it is recommended that replicated concurrent analyses (randomized blocks) of groups of animals be used. That is, some samples from each of the groups of animals to be compared are analyzed at the same time. This process is replicated until a sufficient number of animals are sampled. If replicated concurrent analyses are not conducted and clinical measurements are made at different times for different groups of animals, the biases may be large. Clinical data were examined from several experiments to illustrate that the problems of clinical measurements are not confined to a particular endpoint, species, or sex. In one case, four times as many animals would have been required using nonconcurrent analyses to achieve the same precision as for concurrent analyses. Permutation analyses of two of the data sets indicate that statistical conclusions concerning the comparison of average clinical levels in different groups of animals would have been incorrect, falsely indicating higher or lower levels in a group over one-half of the time with nonconcurrent analyses.     

Self-similarity analysis of eubacteria genome based on weighted graph

We introduce a weighted graph model to investigate the self-similarity characteristics of eubacteria genomes. The regular treating in similarity comparison about genome is to discover the evolution distance among different genomes. Few people focus their attention on the overall statistical characteristics of each gene compared with other genes in the same genome. In our model, each genome is attributed to a weighted graph, whose topology describes the similarity relationship among genes in the same genome. Based on the related weighted graph theory, we extract some quantified statistical variables from the topology, and give the distribution of some variables derived from the largest social structure in the topology. The 23 eubacteria recently studied by Sorimachi and Okayasu are markedly classified into two different groups by their double logarithmic point-plots describing the similarity relationship among genes of the largest social structure in genome. The results show that the proposed model may provide us with some new sights to understand the structures and evolution patterns determined from the complete genomes.     

Locations of methyl groups in 28 S rRNA of Xenopus laevis and man. Clustering in the conserved core of molecule

28 S ribosomal RNA from several vertebrate species contains some 68 to 70 methyl groups. Evidence described in this paper enables some 58 methyl groups to be located in the primary structure of 28 S ribosomal RNA from Xenopus laevis. Most of the locations are unambiguous but a few are currently tentative. In human 28 S ribosomal RNA the great majority of the same sites are methylated as in Xenopus, but there are a few differences between the respective methyl group distributions. The main features of the methyl group distribution are as follows. (1) All of the identified methyl groups are in conserved core regions of 28 S ribosomal RNA. (2) Methylation is much more heavily concentrated in the 3' region of the molecule than in the 5' region (in contrast to 18 S ribosomal RNA, in which there is a major cluster of 2'-O-methyl groups in the 5' region). (3) In addition to the heavily methylated 3' region, clusters of methyl groups occur elsewhere in 28 S ribosomal RNA in the vicinity of domain boundaries. For domains 3 to 6, the two ends of each domain are united in a helix and are linked to adjacent domains either directly or by short single-stranded regions. It therefore follows that the methyl groups near the boundaries of these domains come together into the same general region of the three-dimensional structure. Within this large-scale pattern of distribution, methyl groups occur in a variety of local environments, examples of which are discussed. The triply methylated sequence Am-Gm-Cm-A occurs in a short single-stranded region which links domain 3 to domain 4. Near the 3' end of domain 5 there is a cluster of 11 methyl groups including a 2'-O-methyl pseudouridine in a tract of 160 nucleotides whose sequence is totally conserved between Xenopus and man. These methyl groups are variously distributed between single-stranded regions and short or imperfect but conserved helices. A further cluster of methyl groups including the highly conserved Um-Gm-psi sequence occurs in a region of domain 6 which is implicated in peptidyl transfer. Possible relationships between methylation and other events in ribosome maturation are discussed.     

Equivalence of regression curves sharing common parameters

In clinical trials, the comparison of two different populations is a common problem. Nonlinear (parametric) regression models are commonly used to describe the relationship between covariates, such as concentration or dose, and a response variable in the two groups. In some situations, it is reasonable to assume some model parameters to be the same, for instance, the placebo effect or the maximum treatment effect. In this paper, we develop a (parametric) bootstrap test to establish the similarity of two regression curves sharing some common parameters. We show by theoretical arguments and by means of a simulation study that the new test controls its significance level and achieves a reasonable power. Moreover, it is demonstrated that under the assumption of common parameters, a considerably more powerful test can be constructed compared with the test that does not use this assumption. Finally, we illustrate the potential applications of the new methodology by a clinical trial example.     

A Procedure for the Common Estimation of Parameters Corresponding to Several Treatment Groups

In this article we give a procedure for the common estimation of parameters corresponding to several treatment groups. Thereby we assume that the distribution functions of the groups belong to the same family and differ only in the parameter values. The procedure allows the common estimation of some of these parameters. The parameters themselves will be estimated by the maximum likelihood method; the estimators will be calculated iteratively by the Newton-Raphson method. To prove if the common estimation is possible, we propose as a suitable test the maximum likelihood ratio test. Finally we show the application of our procedure in the case of the probit analysis.     

大刺儿菜和小刺儿菜的植物化学分类学研究

大刺儿菜和小刺儿菜是形态相似的两个近缘类群,其分类学地位一直存在争论,的有学者把它们归并为一个种。本文通过对其叶的黄酮类化合物层析谱进行比较研究,结果表明两个类群都显示出各自的特征斑点;结合其形态学特征,支持将它们作为两个独立的种。     

Regional specificity of developing reticulospinal, vestibulospinal, and vestibulo-ocular projections in the chicken embryo

The regional mapping of reticulospinal, vestibulospinal, and vestibulo-ocular neuron groups onto specific axonal pathways was determined in the chicken embryo by retrograde axonal tracing. Experiments were performed on in vitro preparations of the brain stem to allow for precisely localized tracer injections combined with selective lesions of axon tracts. Brain-stem neuron groups were labelled from 3 days of embryonic development, when the first reticulospinal axons reached the cervical spinal cord, to 9 days of embryonic development, when each of the three systems studied had acquired a relatively mature organization. A striking feature at all stages was the spatial segregation of many neuron groups that projected along different trajectories. Examples of such segregation were found for neuron groups projecting in the same tract on different sides of the brain stem, in different tracts on the same side of the brain stem, and rostrally versus caudally. The occurrence of this segregation from early stages suggests that the choice of projection pathway by many brain-stem neurons is in some way linked to cell position. In some regions of the brain stem, neuron groups projecting along different pathways are intermingled. At least some of this intermingling, however, appears to occur subsequent to the initial establishment of axon projection patterns. Comparison of the mapping patterns at progressively older stages, and with previous mapping in the 11-day-old embryo (Glover and Petursdottir, 1988; Petursdottir, 1990) suggests that these projections are established with little error. The one obvious example of remodelling involved the pontine reticulospinal projection, in which an early contralateral axon population appeared to retract from spinal to medullary levels over the course of a few days. A similar phenomenon may be involved in the elimination of part of the contralateral reticulospinal projection from the midmedulla.     

Regional specificity of developing reticulospinal,vestibulospinal, and vestibulo–ocular projections in the chicken embryo

The regional mapping of reticulospinal, vestibulospinal, and vestibulo–ocular neuron groups onto specific axonal pathways was determined in the chicken embryo by retrograde axonal tracing. Experiments were performed on in vitro preparations of the brain stem to allow for precisely localized tracer injections combined with selective lesions of axon tracts. Brain-stem neuron groups were labelled from 3 days of embryonic development, when the first reticulospinal axons reached the cervical spinal cord, to 9 days of embryonic development, when each of the three systems studied had acquired a relatively mature organization. A striking feature at all stages was the spatial segregation of many neuron groups that projected along different trajectories. Examples of such segregation were found for neuron groups projecting in the same tract on different sides of the brain stem, in different tracts on the same side of the brain stem, and rostrally versus caudally. The occurrence of this segregation from early stages suggests that the choice of projection pathway by many brain-stem neurons is in some way linked to cell position. In some regions of the brain stem, neuron groups projecting along different pathways are intermingled. At least some of this intermingling, however, appars to occur subsequent to the initial establishment of axon projection patterns. Comparison of the mapping patterns at progressively older stages, and with previous mapping in the 11-day-old embryo (Glover and Petursdottir, 1988; Petursdottir, 1990) suggests that these projections are established with little error. The one obvious example of remodelling involved the pontine reticulospinal projection, in which an early contralateral axon population appeared to retract from spinal to medullary levels over the course of a few days. A similar phenomenon may be involved in the elimination of part of the contralateral reticulospinal projection from the midmedulla.     

Studying the evolutionary relationships and phylogenetic trees of 21 groups of tRNA sequences based on complex networks

To find out the evolutionary relationships among different tRNA sequences of 21 amino acids, 22 networks are constructed. One is constructed from whole tRNAs, and the other 21 networks are constructed from the tRNAs which carry the same amino acids. A new method is proposed such that the alignment scores of any two amino acids groups are determined by the average degree and the average clustering coefficient of their networks. The anticodon feature of isolated tRNA and the phylogenetic trees of 21 group networks are discussed. We find that some isolated tRNA sequences in 21 networks still connect with other tRNAs outside their group, which reflects the fact that those tRNAs might evolve by intercrossing among these 21 groups. We also find that most anticodons among the same cluster are only one base different in the same sites when S ≥ 70, and they stay in the same rank in the ladder of evolutionary relationships. Those observations seem to agree on that some tRNAs might mutate from the same ancestor sequences based on point mutation mechanisms.     

Individual foraging specialisation in a social mammal: the European badger (Meles meles)

Individual specialisation has been identified in an increasing number of animal species and populations. However, in some groups, such as terrestrial mammals, it is difficult to disentangle individual niche variation from spatial variation in resource availability. In the present study, we investigate individual variation in the foraging niche of the European badger (Meles meles), a social carnivore that lives in a shared group territory, but forages predominantly alone. Using stable isotope analysis, we distinguish the extent to which foraging variation in badgers is determined by social and spatial constraints and by individual differences within groups. We found a tendency for individual badgers within groups to differ markedly and consistently in their isotope values, suggesting that individuals living with access to the same resources occupied distinctive foraging niches. Although sex had a significant effect on isotope values, substantial variation within groups occurred independently of age and sex. Individual differences were consistent over a period of several months and in some instances were highly consistent across the two years of the study, suggesting long-term individual foraging specialisations. Individual specialisation in foraging may, therefore, persist in populations of territorial species not solely as a result of spatial variation in resources, but also arising from individuals selecting differently from the same available resources. Although the exact cause of this behaviour is unknown, we suggest that specialisation may occur due to learning trade-offs which may limit individual niche widths. However, ecological factors at the group level, such as competition, may also influence the degree of specialisation.     

Pregnancy wantedness: attitude stability over time

In this analysis we have compared two attitudinal reports, from interviews two years apart, of the same event for consistency over time. We have looked at women's self-reports, and at their proxy reports for partners' attitudes as well. The inconsistent reports of women's own views tended to shift slightly toward more favorable reports at the second interview (15 percent more positive versus 10 percent more negative). More specifically, 7.5 percent of women who reported at Time 1 that their most recent births had been unwanted switched to more favorable reports at Time 2, and about the same percentage of women who reported Table 4, the findings would suggest that some of the groups typically considered to be most "at risk" were those who were also most apt to report inconsistently. This findings should signal some concern in the policy community. Net of other factors, there is no effect of income, but a number of at-risk groups remained significantly more likely than others to change their reports over time. Of particular concern is the finding that women who reported their pregnancies as mistimed or unwanted were so much more likely to change their reports over time than were women who initially said that their pregnancies had been well timed. When we look at the direction of change, it is clear that, with some exceptions, the more "at risk" groups were more likely to shift in a more negative direction, while the less "at risk" groups were less likely to do so; and at times they were more likely to report more favorably at the second interview. Although somewhat hampered by small sample sizes in the analysis of Time 1 mistimed and unwanted reports, results confirmed that certain subgroups were not only more apt to report inconsistently, they were also more likely to do so in specific directions. To the extent that future survey questions can emphasize to respondents that they should focus on the time of conception, and not on current status, inconsistency across groups may be reduced.     

Symmetry and the tentacular apparatus in Cnidaria

Comparative analysis provides evidence that bilateral symmetry is a primary character of Cnidaria. All anthozoan taxa are characterized by bilateral symmetry. The anthozoan pharyngeal plane is a plane of bilateral symmetry of mesenteries and, at the same time, it is a plane of bilateral symmetry of regulatory gene expression in anthozoan morphogenesis. In Medusozoa, the bilateral symmetry is replaced by radial symmetry, but some hydrozoans (for example, Corymorphidae) demonstrate bilateral symmetry. The bilateral symmetry of Cnidaria is thought to be inherited from the common ancestors of both cnidarians and triploblastic bilaterians. The secondary radial symmetry of Cnidaria evidently is a result of the adaptation to the sessile mode of life. The presence of both the marginal and labial rings of tentacles is supposed to be a plesiomorphic character of Cnidaria. In some groups of cnidarians, one of the tentacle rings may be reduced.     

Preferential usage of some minor codons in bacteria

In many bacterial species, such as Deinococcus radiodurans, Haemophilus influenzae, and Methanobacterium thermoautotrophicum, some minor codons are preferentially used near the initiation codon. Among these codons, there are some minor codons that have strong preference for the initiation site in the high codon adaptation index (CAI) group (comprising of highly expressed genes) rather than in the low CAI genes group (comprising of low expressing genes). In the present study, codon usage in the initiation site and in the rest of the gene was systematically compared in the 27 complete bacterial genomes and Saccharomyces cerevisiae genome. Furthermore, we classified genes into two groups according to the CAI values and conducted the same analysis for each of the two groups. Our results suggest a role for some minor codons in the initiation site of the regulating translation system in many bacteria. We have summarized codons that are preferentially used in the initiation site and probably play a role in regulating genes expression in these organisms.     

'First' appearances in the Cenozoic land-mammal record of the Greater Antilles: significance and comparison with South American and Antarctic records

Aim Through analysis of fossil records, the aim of this paper is to show that fossil representatives of at least three land‐mammal clades (pitheciine atelid primates, heteropsomyine echimyid rodents, and megalonychid phyllophagan xenarthrans) that once lived in the Greater Antilles are as old as, if not older than, ‘first’ occurrences of these same groups on the South American mainland. Location Greater Antilles, South America, Antarctic Peninsula. Methods Analysis of Cenozoic land‐mammal fossil records for the three areas. Results Comparison reveals an interesting similarity to the Tertiary vertebrate palaeontological record for the Antarctic Peninsula (Seymour Island), in the sense that the latter also includes early (Eocene) representatives of some typical ‘South American’ groups (e.g. meridiungulates, sloths, certain marsupial groups). Conclusions Given how limited the Antillean and Antarctic records are in quantity and quality, it seems unlikely that these ‘first’ appearances have much bearing on real origins (basal divergences). Rather, it suggests that the fossil basis for interpreting the origin and earliest diversification of ‘South American’ clades during the latest Cretaceous/early Cenozoic is probably even scantier than generally realized. In particular, the Antillean record strengthens arguments that some crown‐group continental lineages are considerably older than fossil evidence currently allows – a point increasingly (if unevenly) supported by molecular studies of many of the same clades.     

Mating and Residence Patterns of Male Patas Monkeys

A longterm study of a population of patas monkeys (Erythrocebus patas) in Kenya indicated fluid male residence patterns. While a single adult male was present in each of the two main study groups for most of each year, several males were present and mating in groups during some conception periods. Tenures of males in heterosexual groups were generally short; some males were resident in both groups and some had more than one tenure in the same group. When not in heterosexual groups, males lived as solitaries or in all-male associations.     

Quantitative integration of genetic factors in the learning and production of canary song

Learned bird song is influenced by inherited predispositions. The canary is a model system for the interaction of genes and learning on behaviour, especially because some strains have undergone artificial selection for song. In this study, roller canaries (bred for low-pitched songs) and border canaries (whose song is higher pitched, similar to the wild-type) were interbred and backcrossed to produce 58 males that sorted into seven genetically distinct groups. All males were tutored with the same set of songs, which included both low- and high-pitched syllables. Individuals were consistent within genetic groups but differed between groups in the proportion of low- versus high-pitched syllables they learned and sang. Both sex-linked and autosomal factors affected song learning and song production, in an additive manner. Dominant Z-chromosome factors facilitated high-pitched syllable learning and production, whereas the sex-linked alleles associated with the switch to low-pitched syllables under artificial selection were largely recessive. With respect to autosomal effects, the most surprising result is that males in the same genetic group had almost identical repertoires. This result challenges two common preconceptions: that genetic changes at different loci lead to distinct phenotypic changes, and that genetic predispositions affect learning in simple and general ways. Rather, different combinations of genetic changes can be associated with the same phenotypic effect; and predispositions can be remarkably specific, such as a tendency to learn and sing one song element rather than another.     

Extension of the rank sum test for clustered data: two-group comparisons with group membership defined at the subunit level

The Wilcoxon rank sum test is widely used for two-group comparisons for nonnormal data. An assumption of this test is independence of sampling units both between and within groups. In ophthalmology, data are often collected on two eyes of an individual, which are highly correlated. In ophthalmological clinical trials, randomization is usually performed at the subject level, but the unit of analysis is the eye. If the eye is used as the unit of analysis, then a modification to the usual Wilcoxon rank sum variance formula must be made to account for the within-cluster dependence. For some clustered data designs, where the unit of analysis is the subunit, group membership may be defined at the subunit level. For example, in some randomized ophthalmologic clinical trials, different treatments may be applied to fellow eyes of some patients, while the same treatment may be applied to fellow eyes of other patients. In general, binary eye-specific covariates may be present (scored as exposed or unexposed) and one wishes to compare nonnormally distributed outcomes between exposed and unexposed eyes using the Wilcoxon rank sum test while accounting for the clustering. In this article, we present a corrected variance formula for the Wilcoxon rank sum statistic in the setting of eye (subunit)-specific covariates. We apply it to compare ocular itching scores in ocular allergy patients between eyes treated with active versus placebo eye drops, where some patients receive the same eye drop in both eyes, while other patients receive different eye drops in fellow eyes. We also present comparisons between the clustered Wilcoxon test and each of the signed rank tests and mixed model approaches and show dramatic differences in power in favor of the clustered Wilcoxon test for some designs.