Studies in the Genus Elaphoglossum Schott: II. The Root and Bud Traces

Further investigations upon some Jamaican species of Elaphoglossumhave shown that, parallel to a series of stelar forms demonstratedearlier, there is another series showing a progressive reductionof the lateral bud trace. The anatomical differences betweenthe root and bud traces are indicated and the development ofthe stele in a young outgrown bud is described.     

Karyotype of sculpin,Myoxocephalus stelleri from Peter the Great Bay, Sea of Japan

We studied the karyotype of the frog sculpinMyoxocephalus stelleri Tilesius (Cottidae) from Peter the Great Bay: 2n=40; NF=46. In the series of two-armed chromosomes, there is a pair of large submetacentric ones, while there are two pairs of large subtelocentric chromosomes in the one-armed series. Ag-NOR staining revealed nucleolus organizer regions in the short arms of two pairs of subtelocentric chromosomes that differed in size. We found neither differences between male and female karyotypes nor variability of any type. The karyotype ofM. stelleri is compared with that of the short-spined sea scorpionM. scorpius.     

Lung cancer risk and variation in MGMT activity and sequence

O(6)-Alkylguanine-DNA alkyltransferase (MGMT) repairs DNA adducts that result from alkylation at the O(6) position of guanine. These lesions are mutagenic and toxic and can be produced by a variety of agents including the tobacco-specific nitrosamines, carcinogens present in cigarette smoke. Here, we review some of our work in the context of inter-individual differences in MGMT expression and their potential influence on lung cancer risk. In humans there are marked inter-individual differences in not only levels of DNA damage in the lung (N7-methylguanine) that can arise from exposure to methylating agents but also in MGMT activity in lung tissues. In the presence of such exposure, this variability in MGMT activity may alter cancer susceptibility, particularly as animal models have demonstrated that the complete absence of MGMT activity predisposes to alkylating-agent induced cancer while overexpression is protective. Recent studies have uncovered a series of polymorphisms that affect protein activity or are associated with differences in expression levels. The associations between these (and other) polymorphisms and cancer risk are inconsistent, possibly because of small sample sizes and inter-study differences in lung cancer histology. We have recently analysed a consecutive series of case-control studies and found evidence that lung cancer risk was lower in subjects with the R178 allele.     

Estimating woody and herbaceous vegetation cover from time series satellite observations

In this paper we test a method to estimate the tree and grass vegetation cover over Australia from satellite-derived normalized difference vegetation index (NDVI) time series (monthly 1981–91, ≈5 km pixels) observations. The evergreen cover is assumed to track along the base of the NDVI time series, which is assumed to be equivalent to the woody vegetation cover. The base of the NDVI time series is estimated using modifications to a classical econometric model (i.e. time series is the sum of trend, seasonal and random components). Estimates of the average evergreen component during 1982–85 and 1986–89 were generally consistent with known vegetation distributions. Changes in evergreen cover were largely restricted to the south-west and south-east of Australia. Those changes were largely the result of differences in rainfall between the two periods. The proposed method for estimating woody vegetation cover is found to be generally robust. However, there are some regions where the grass (or pasture) is mostly evergreen. Some possible refinements are proposed to handle such cases.     

基于复杂性度量的心率变异信号非线性分析

假设心率变异信号是累积－发放模型（Ｉｎｔｅｇｒａｔｅ－ｆｉｒｅ）与非线性动力学系统耦合产生的峰电位链（ＳｐｉｋｅＴｒａｉｎ）。以符号动力学为基础,提出利用峰电位间隔（ｉｎｔｅｒｓｐｉｋｅｉｎｔｅｒｖａｌ,ＩＳＩ）及其随机替代数据的Ｃ１、Ｃ２复杂度来定量刻划非线性动力学系统特性。结果表明：确定性驱动产生的峰电位间隔序列可以与随机性驱动产生的峰电位间隔序列区分开。因此,在噪声干扰较强的生理信号中,尤其是在不清楚非线性动力系统变量和峰电位间隔序列之间是否存在微分同胚的情况下,以复杂性度量来代替以Ｔａｋｅｎｓ嵌入定理为基础的关联维数、Ｌｙａｐｎｏｖ指数等描述动力系统特征的方法是合适的。最后通过２类共３７个个体,每个个体的心电数据为１０００个Ｒ－Ｒ间期的微分序列检验心率变异信号的非线性结构。     

贵州典型峰丛洼地区域近50年村落演变规律及驱动机制

揭示当前多种因素驱动下聚落演变模式与功能转型的地域差异具有重要意义。通过长时间序列的高清影像数据,研究典型峰丛洼地区不同自然和社会经济条件下,近50年来,尤其最近10年乡村聚落在多重背景下的演变模式、内在机制,及其地域差异。结果发现:(1)研究区聚落分布分部主要受耕地、地形和道路的影响,聚落面积增长热点和聚落斑块增长热点的耦合关系存在区域差异;(2)聚落格局演变存在集聚与均匀分布两种趋势;(3)研究区聚落特征和演变的阶段性地域差异十分明显;(4)喀斯特山区聚落的规模变化、演变阶段和演变模式既存在一些共同性的特征,又有各自的差异性;(5)外部因素和聚落农户的自我调适是演化的主要驱动力。     

Comparisons of the polypeptide chains of globins

Summary Vertebrate myoglobins and hemoglobins each consist of units containing a heme group and an associated polypeptide chain. The polypeptide chains form an homologous series and can be compared with each other to measure amino acid differences and minimum base differences per codon. These differences are the result of mutations which have been incorporated during divergent evolution from a common ancestral gene. Each such base replacement is termed an evolutionary event. Each amino acid replacement is the result of one or more evolutionary events. However there can be only one amino acid difference between two sites. The minimum mutational difference between two sites is perceptible only as one, two or three base differences per codon, but there may be more evolutionary events than base differences, because of revertants and multiplicity of base replacements at the same site. When all three bases in a codon are changed, the result is recognizable in only about five per cent of cases. Therefore such recognizable three-base changes indicate a large number of evolutionary events.     

Group mating among Norway rats I. Sex differences in the pattern and neuroendocrine consequences of copulation

The copulatory pattern of groups of rats (Rattus norvegicus) was studied in the laboratory in a seminatural environment. In a given mating session, every oestrous female copulated with each male; likewise, every male copulated with each oestrous female. While individual males and females experienced similar amounts of copulation, there were dramatic sex differences in sequence and temporal pattern. Males mated in a multiple intromission pattern and had more ejaculatory series when several females were in oestrus. In contrast, females received intromissions and ejaculations in a random order, not in the sequence of a male ejaculatory series. Males copulated at shorter intervals than females did, a temporal sex difference that was determined by the pattern of female solicitations and male approaches. These sex differences are used to discuss the different units of analysis that are appropriate for male and female sexual behaviour in this species. Furthermore, the sex differences in the temporal pattern of copulation which emerged during group mating parallel the known sex differences in the temporal parameters of the neuroendocrine reflexes which mediate successful reproduction in the domestic strain.     

Mapping of dihydrofolate-reductase receptor site by correlation with minimal topological (steric) differences

A procedure for obtaining the shape of (or part of the shape of) a receptor site cavity based on structures of molecules with known activities is outlined and applied to dihydrofolate reductase inhibitors. The procedure consists of determining the optimal standard for calculating the minimal topological (steric) differences (MTD, number of unsuperposable atoms when a molecule is superimposed over the standard). For a series of 15 diaminopyrimidines, substituted in position 5 with aliphatic, cyclo-aliphatic or arylic groups, the correlation of inhibitory power with MTD and π-Hansch hydrophobicity gives a coefficient r = 0.981, while correlating with π only, r = 0.767 is obtained. This procedure may be useful in obtaining quantitative structure-activity correlations for series of non-congeneric molecules, if there are no marked changes in polar groups.     

A Critical Comparison of Two Long-term Zooplankton Time Series from the Central-west North Sea

Long-term changes in relative and absolute zooplankton abundanceand species composition were compared between the Dove MarineLaboratory and Continuous Plankton Recorder (CPR) time seriesin the central-western North Sea. The two time series employdifferent sampling mechanisms, with the Dove series beng obtainedby net sampling at a fixed station off the Northumberland coast,while the CPR series utilizes a network of fixed towed routes. It was found that there was a significant correlation (r =0.64, P < 0.001) between the relative year-to-year fluctuations of the two series and a significant agreement in the pattern of year-to-year variations in species composition of the dominant taxa (P = 0.01) over the majority of the time period. However, examination of absolute zooplankton abundances found large differences between the two time series. Differences in mesh size and in the sample processing methodologies were not wholly responsible for these. Model-derived catching efficiencies for the two sampling devices suggested that differences in absolute abundances may have been mainly due in some taxa to a greater degree of active avoidance of the CPR sampling device by zooplankton, although it is likely that passive avoidance as a result of hydrodynamic factors has a role.>     

Tooth crown size differences between age groups: A possible new indicator of stress in skeletal samples

Juveniles and adults from a prehistoric Amerindian skeletal series from Tennessee are compared for differences in the means and variances of the buccolingual dimensions of their permanent teeth. While there are no significant differences in variance, it is found that juveniles exhibit significantly smaller mandibular canines, first premolars, and first molars. The results are similar to those of a previous examination of an Amerindian skeletal collection from South Dakota. There is evidence to suggest that teeth may fail to develop to their maximum genetic size potential when there is interference from exogenous chronic stressors such as malnutrition or disease. Archeological and biological evidence demonstrates that both the Tennessee and South Dakota series represent groups that suffered considerably from environmental stressors. It is suggested that those persons who suffered most were more likely to die prematurely, thus explaining why juvenile skeletons tend to have smaller teeth. The conclusion is that the examination of age variation in crown size can be a useful supplement to other osteological indicators of stress in skeletal collections. The factor of sex ratio and the implications of the results for other kinds of dental metric studies are discussed.     

Carboxylesterases (EC 3.1.1). Amino acid composition of liver carboxylesterases.

The amino acid compositions of the carboxylesterases from chicken, ,orse, ox, sheep, and pig livers are reported and compared. As would be expected for this homologous series, the compositions show a general similarity. However, there are some significant differences, but the degree to which particular pairs of enzymes differ is consistent with the evolutionary history of the species from which they were isolated.     

Root Density and Water Potential Gradients near the Plant Root

The models of Gardner (1960) and Cowan (1965) for water transferto the plant root are used to estimate the differences in waterpotential between the root and the bulk soil for a wide rangeof root densities and water extraction rates at a series ofmatric potentials for a Yolo light clay. For root densities and extraction rates reported both in theliterature and in this paper there is good evidence to suggestthat the large potential gradients originally predicted by Gardnerand Cowan are restricted to situations involving very low rootdensities and high extraction rates in relatively dry soil.     

Disentangling Ethnicity and Context as Predictors of Parenting Within Rural African American Families

This study will address the initial question: Are there ethnic differences in parenting that remain when contextual variables are controlled and are related to culture, focusing on two samples of rural African American families. This study is part of a series of coordinated studies presented in this special issue (Le et al., 2008). Specific attention was given to ascertaining whether these differences were explained by contextual factors, such as socioeconomic factors (i.e., parents' educational level, homeownership, family structure, and number of children in the household). Finally, this study examined whether any differences in parenting (warmth, monitoring, communication) were attributed to cultural factors, after controlling for the contributions of contextual factors. Results indicate that parental education, family size, negative life events, racial discrimination, neighborhood characteristics, and religiosity were significantly associated with various domains of parenting among rural African Americans.     

First results of a randomized clinical trial of fast neutrons compared with X or gamma rays in treatment of advanced tumours of the head and neck. Report to the Medical Research Council.

Results of the first randomized clinical trial to compare the effects of fast neutrons and those of x or gamma rays (photons) in treating patients with advanced tumours of the head and neck are reported. In 37 out of 52 patients treated with neutrons and 16 out of 50 treated with photons the local tumour completely regressed; the tumour later recurred in nine of the 16 photon patients but in none of the 37 neutron patients. The advantages to the neutron-treated patients were seen in tumours of well and poorly differentiated histology and in each site. Complications after treatment did not differ significantly between the groups. Despite these substantial differences in local control of the tumour there were no significant differences in mortality between the series. A detailed study of the effective doses and the response of tumours and normal tissue in each series indicated that the improved results from neutron therapy were due to differences in the biological quality of the beam and not to the rather higher average effective dose in the neutron series. To assess the long-term effects of neutron treatment patients in earlier stages of disease and with smaller tumours should be included in the next phase of the trial.     

Effects of Mixed Cropping on a Soil Nematode Community in Honduras

Nematode-resistant tropical legumes are effective in reducing populations of plant-parasitic nematodes when used in rotation systems. Mixed cropping is a common practice of many small farmers in Central America, but little is known about the effects of tropical legumes on nematode communities under these systems. To examine the effects of intercropping on the nematode fauna associated with squash (Cucurbita pepo) and cucumber (Cucumis sativa) in Honduras, two field experiments were conducted to compare nematode density and diversity in soil under cucurbits grown as a monocrop with that in soil under cucurbits intercropped with alfalfa (Medicago sativa) or hairy indigo (Indigofera hirsuta). A parallel series of field tests compared soil nematode communities associated with a cucurbit monocrop and a cucurbit intercropped with marigold (Tagetes patula), which may decrease nematode populations through the production of toxic root exudates. Among all four tests, over a period of 90 days, there were no consistent differences in densities of various nematode genera or trophic groups in intercropped versus monocropped plants, nor were there consistent differences in community diversities among treatments.     

Fingerprints of Whites and Negroes from Southern Brazil

Studies on 1,115 individuals (451 Whites, 240 Light Mulattoes, 236 Dark Mulattoes and 188 Negroes) from Pôrto Alegre, Brazil are reported. The differences among those subgroups are not large and there is not a clear gradient when we consider samples with increasing Negro ancestry. The most marked difference between Whites and the total Negroid group occurred in the prevalence of radial loops. Comparison with Portuguese and African series indicates that no single factor can fully explain the observed distributions. But the values of Dankmeijer's index are exactly those expected on the assumption of 50% White admixture in the Pôrto Alegre Negro, in agreement with previous investigations.     

Lipopolysaccharide Composition of the Wilt Pathogen, Pseudomonas solanacearum: CORRELATION WITH THE HYPERSENSITIVE RESPONSE IN TOBACCO

In the induction of the hypersensitive response (HR) in tobacco by Pseudomonas solanacearum, the recognition between host and pathogen is thought to involve an interaction between plant lectins and bacterial lipopolysaccharide (LPS). The LPS of a series of strains of P. solanacearum were examined to determine if there are structural differences that might account for the ability or inability of these strains to induce the hypersensitive response. Analysis of the components of LPS by gas chromatography indicates a clear difference in sugar composition between the HR-inducing and non-HR-inducing strains, especially in terms of the percentage of glucose, xylose and rhamnose. Sodium dodecyl sulfate polyacrylamide gel electrophoresis shows there are two distinct kinds of LPS, differing greatly in size, which correspond to rough and smooth LPS in other systems. In addition, a phage, CH154, was isolated which lyses non-HR-inducing bacteria and which is inactivated by LPS from these bacterial strains. Therefore, differences in LPS structure correlate strongly with host recognition of Pseudomonas solanacearum.     

Evaluation of the gonial angle in the Anatolian populations: from past to present

Biometrical studies on ancient skeletal series and comparison with modern people by using radiological methods are quite limited in Turkey. Previous studies showed that measurements obtained from orthopantomographs are highly correlated with the actual size of the bones. The aim of the present study is to determine the possible change in gonial angle over time in ancient Anatolian populations with the present. Also an aim was attempted to demonstrate the symmetry of the gonial angle in the jaws and the sexual dimorphism. Gonial angle values (right and left) were taken from 267 Turkish adults with no craniomandibular disorders, orthodontic history or treatment by using panoramic radiographs. Data of the past populations were collected from previous studies. Comparison between right and left sides and the sexual differences were tested by paired student t-test and discriminant analyses were conducted. The results showed that there were no significant differences between the right and left gonial angles of the individuals but there was a significant difference at the left gonial angle between sexes (p < 0.01). Furthermore, no statistically significant difference was found for the gonial angle between the selected past populations with the present sample.     

Novel 2-aminobenzothiazoles as selective neuronal nitric oxide synthase inhibitors

A series of substituted 2-aminobenzothiazole compounds have been synthesized and evaluated as nitric oxide synthase (NOS) inhibitors. Compound 14 shows activity in the nM range and is selective for the human neuronal NOS isoform. We have also evaluated the compounds against the rat NOS isoforms. For some of the compounds, there are significant differences in NOS inhibitory activities between the human and rat enzymes. For example, compound 10b has nM activity against the rat nNOS while low microM activity against the human nNOS.