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PubMed2006

Multi-character population study of the vir subtelomeric multigene superfamily of Plasmodium vivax, a major human malaria parasite.

Plasmodium vivax, the most widely distributed human malaria parasite, contains the subtelomeric multigene vir superfamily corresponding to circa 10% of its coding genome. In this work, we used a multi-character strategy to study the vir gene repertoire circulating in natural parasite populations obtained directly from 32 human patients from endemic regions of Brazil and Sri Lanka. Cladistic analysis confirmed the existence of vir subfamilies, which varied in size and allele polymorphisms. Moreover, different motifs, protein domain, and secondary structures were predicted for each subfamily. Of importance, not all vir sequences possess a recognizable Pexel motif recently shown to be important, though not essential, signal for transportation to the cell membrane of infected red blood cells. Furthermore, subfamilies A and D display common structural features with the recently described P. falciparum SURFIN and Pfmc-2tm subtelomeric multigene families. These results suggest that VIR proteins can have different subcellular localizations and functions. This is the first study on a population level of the P. vivax vir subtelomeric multigene superfamily.

Amino Acid Motifs↗

PubMed2004

The Character-line Bisection Task: a new test for hemispatial neglect.

A failure to report or respond to stimuli presented in a portion of space is termed hemispatial neglect. Line bisection and line cancellation are two of the tests used most commonly to assess for neglect. Perhaps, because neglect can be induced by a variety of deficits, neither of these tests used alone is as sensitive as both used together. Hence, the primary purpose of this study was to assess the sensitivity, reliability and validity of a new test called the Character-line Bisection Task (CLBT) that combines features of both the bisection and cancellation tests. Since local attention and language are primarily mediated by and activate the left hemisphere, our second goal was to learn if the CLBT and especially the letter version induce a greater rightward bias than the solid-line bisection task. Eighty patients with acute right hemisphere stroke and 81 controls performed the CLBT that consists of two subtests, the Letter-line and Star-line Bisection tasks. All subjects also completed four conventional tests for neglect (Standard solid-line bisection, line cancellation, Star Cancellation, and figure copying). In the bisection tasks both patients and controls bisected to the right with the CLBT than with the solid-line bisection task, suggesting the CLBT induces asymmetrical hemispheric activation. This enhanced rightward deviation with the CLBT was the same for the Letter-line and Star-line Bisection tasks. In regard to sensitivity, we defined the presence of neglect syndrome based on a total score derived from performance of controls on all six tests. This total score detected 55 (68.8%) patients with neglect. Within this group, the Letter-line and Star-line tasks diagnosed neglect in 50 and 48 patients, respectively, resulting in the highest sensitivities (90.9, 87.3%) of the six tests. Thus, the CLBTs demonstrated higher sensitivities than the other commonly used neglect tests and these new tests can be useful for the detection and quantification of unilateral neglect.

Adult↗

PubMed2006

The possible premalignant character of oral lichen planus and oral lichenoid lesions: a prospective five-year follow-up study of 192 patients.

Recently, we reported the preliminary results of a prospective study on the possible premalignant character of oral lichen planus (OLP) and oral lichenoid lesions (OLL). Based on these data it was concluded that there was some but no convincing support for the hypothesis that patients with OLL have an increased risk of development of oral cancer, but not so in patients with OLP. In the present treatise the results of prolonged follow-up of this cohort of patients have been described. A study group of 192 patients, 67 patients diagnosed with OLP and 125 patients with OLL, according to revised World Health Organization diagnostic criteria, was followed for periods ranging from 7.6 to 96.9 months (mean, 55.9 months). The expected number of patients with oral cancer in the group of patients with OLP and in the group of patients with OLL was estimated by comparing the number of patients, their ages, sex, and the length of follow-up to annual incidence rates of oral cancer for the general population in The Netherlands. The binomial test was used to determine whether the observed number of cases of cancer in the OLP group and the OLL group exceeded the expected numbers. Four out of 192 patients, two men and two women, developed a squamous cell carcinoma of the oral mucosa during follow-up. All malignant transformations occurred in the OLL group. The malignant transformation of the OLL group, based on a mean follow-up of 53.8 months, was calculated at 0.71% per year. A comparison of the expected against actual figures for the development of carcinomas revealed no increase in patients with OLP and a 142-fold increase in patients with OLL, the latter being statistically significant, with a p-value of 0.044. The present data give support to the hypothesis that patients with OLL have an increased risk of development of oral cancer. There seems to be no increased risk in patients with OLP. In view of our results we advise to monitor only the subgroup of OLL patients twice a year for early detection of possible malignant transformation.

Adolescent↗

PubMed2004

Antioxidant dehydrotocopherols as a new chemical character of Stemona species.

From the roots of various Stemona species four new dehydrotocopherols (chromenols) were isolated and their structures and stereochemistry elucidated by spectroscopic methods. The double bond between C-3 and C-4 proved to be a typical chemical character of the genus found in most of the species. Various C-methylations of the aromatic ring reflect differences in methyltransferase activities and agreed with the current species delimitations showing an exclusive accumulation of dehydro-delta-tocopherol for the Stemona tuberosa group, whereas different provenances of Stemona curtisii were characterized by dehydro-gamma-tocopherol accompanied by small amounts of dehydro-alpha-tocopherol. From Stemona collinsae all four tocopherols were isolated with a clear preponderance of dehydro-delta-tocopherol accompanied by smaller amounts of the rare dehydro-beta-tocopherol. Stemona burkillii and a group of unidentified species showed a weak accumulation trend towards dehydro-alpha-tocopherol, whereas Stemona cochinchinensis and especially Stemona kerrii clearly differed by a preponderance of chromanol derivatives. In Stemona cf. pierrei no tocopherols could be detected at all. Based on TLC tests and microplate assays with the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*) the antioxidant capacities of all chromenol derivatives were comparable with that of alpha-tocopherol showing no significant differences among each other, except for a more rapid kinetic behaviour of the 5,7,8-methylated dehydro-alpha-tocopherol.

Antioxidants↗

PubMed2005

A functional MRI comparison of patients with obsessive-compulsive disorder and normal controls during a Chinese character Stroop task.

Recent functional neuroimaging and neuropsychological studies have suggested that abnormal activity in the anterior cingulate cortex (ACC) might cause an action-monitoring dysfunction in obsessive-compulsive disorder (OCD). To identify the relationship between brain dysfunction and cognitive dysfunction, we examined regional brain changes in OCD with functional magnetic resonance imaging (fMRI) during the performance of a cognitive task. Participants comprised 24 patients with OCD and 14 normal controls. First, we compared the cognitive function in the two groups as assessed by several neuropsychological tests. Then we used fMRI to explore brain correlates of their performance during the Chinese character version of the Stroop test, a task that is strongly related to action-monitoring function. The two groups did not differ on the neuropsychological tests. Both groups also showed similar activation pattern on fMRI. The patients, however, showed weaker activation than the normal controls in the ACC and the right caudate nucleus.

Adult↗

PubMed2004

Temporal variations of mineral character of acid-producing pyritic coastal sediments, Southeast Queensland, Australia.

The lower Pimpama River catchment possesses many features of morphology, geology and landuse, typical for Southeast Queensland. Pimpama River and its main tributary Hotham Creek meander over a coastal plain which developed during the last several thousand years as a result of sea level fluctuations and changing fluvial and estuarine regimes which provided ideal conditions for the formation of sedimentary pyrite. A complex mixture of natural and human factors triggers and controls the oxidation and hydrolysis of this pyrite. The consequent production of sulfuric acid and leaching of metals from the pyrite-rich sediments represent main environmental issues of this coastal setting. This study aimed to determine the lithological character of the coastal unconsolidated sediments, and identify changes produced by acidity over a long period of time in a natural system and over a short period of time in a laboratory system. The mineral composition of the estuarine sediments of the coastal plain reflects the lithology of their source, the geological basement, and also the enhanced weathering rate due to acid production. The primary minerals present in the sediments consist of quartz and feldspars (primarily albite, K-feldspars to a lesser extent and minor anorthite) the product of physical weathering of bedrock material, mainly sandstone. Kaolinite is the dominant clay mineral and represents the product of intense leaching of feldspars promoted by acid conditions. Kaolinite is fairly ordered in structure in fresh and weathered bedrock and it becomes disordered in the estuarine sediments. Illite is mainly present in bedrock-related samples and the highest amounts are associated with muscovite. In the tidal sediments, illite is present to a lesser extent and is not found in the lower estuary. The distribution of mixed layers of smectite-illite is highly variable and their deposition is mainly controlled by the hydrodynamic conditions of the environment. Only low energy tidal settings favour the deposition of smectites. Pyrite is present at many sites and is always accompanied by oxidation products such as jarosite and gypsum. The laboratory experiment showed that in the short-term, changes induced by acid production mainly involved the: (1) decomposition of oxidation products such as gypsum and jarosite, (2) weathering of feldspars (mainly plagioclase), and (3) increased amount of kaolinite and possible increased structural disorder. These observations are of significance when considering wetlands as a method of remediating acid-producing areas by re-establishment of reducing conditions. Jarosite is quite widespread and can represent a source of acid over a short period of time in water-saturated, partially oxidized pyrite-rich sediments. The initial several months of a wetland establishment may, however, be dominated by secondary acid production and metal leaching from preexisting oxidation products like jarosite and natrojarosite.

Journal Article↗

PubMed2003

Waddington's widget: Hsp90 and the inheritance of acquired characters.

Conrad Waddington published an influential model for evolution in his 1942 paper, Canalization of Development and Inheritance of Acquired Characters. In this classic, albeit controversial, paper, he proposed that an unknown mechanism exists that conceals phenotypic variation until the organism is stressed. Recent studies have proposed that the highly conserved chaperone Hsp90 could function as a "capacitor," or an "adaptively inducible canalizer," that masks silent phenotypic variation of either genetic or epigenetic origin. This review will discuss evidence for, and arguments against, the role of Hsp90 as a capacitor for morphological evolution, and as a key component of what we call "Waddington's widget."

Animals↗

PubMed2006

The use of genome-level characters for phylogenetic reconstruction.

Now that large-scale genome-sequencing projects are sampling many organismal lineages, it is becoming possible to compare large data sets of not only DNA and protein sequences, but also genome-level features, such as gene arrangements and the positions of mobile genetic elements. Although it is unlikely that comparisons of such features will address a large number of evolutionary branch points across the broad tree of life owing to the infeasibility of such sampling, they have great potential for resolving many crucial, contested relationships for which no other data seem promising. Here, I discuss the advancements, advantages, methods, and problems of the use of genome-level characters for reconstructing evolutionary relationships.

Genome↗

PubMed2005

First-principles study on incidence direction, individual site character, and atomic projection dependences of ELNES for perovskite compounds.

The incidence direction dependence, the individual site character dependence, and the atomic projection dependence of O-K near edge fine structure of the EEL spectrum (ELNES) from YBa2Cu3O7 (YBCO) and SrTiO3 were theoretically simulated using the first-principles band structure calculation. In order to calculate ELNES, a core-hole was introduced at the oxygen 1s orbital, and sufficiently large supercells composed of more than 100 atoms were employed. We found that the intensity of the first peak of O-K ELNES from YBCO strongly depends on the atomic projection direction, and disappears when the spectrum is measured with the other projection directions. The large projection dependence was also predicted in the O-K ELNES of SrTiO3. It was found that those spectral changes according to the position of the projection are caused by the unidirectional Ti-O-Ti bond in SrTiO3.

Journal Article↗

PubMed2004

Altered permeability and modulatory character of connexin channels during mammary gland development.

Abrupt developmental changes occur in structural form and function of connexin (Cx) channels in the mouse mammary gland. Microarray study shows that the principal connexin isoform in epithelial cells during pregnancy is Cx26, up-regulated and persisting from the virgin. After parturition, there is rapid induction of Cx32. In epithelial plasma membranes, size exclusion chromatography reveals that Cx32 organizes initially with Cx26 as heteromeric (Cx26-Cx32) hemichannels and later in heteromeric and homomeric Cx32 channels. Dramatic alterations of connexin channel function following these developmental changes in channel composition are characterized using native channels reconstituted into liposomes. Changes to channel stoichiometry increase the allowable physical size limits of permeant after parturition; the new Cx32 channels are wider than channels containing Cx26. Most remarkably, heteromeric Cx26-Cx32 channels are selectively permeability to adenosine 3',5' cyclic phosphate (cAMP), guanosine 3',5' cyclic phosphate (cGMP), and inositol 1,4,5-triphosphate (IP(3)), whereas homomeric channels are not. Homomeric Cx26 and heteromeric channels with high Cx26/Cx32 stoichiometry are also inhibited by taurine, an osmolyte playing a key role in milk protein synthesis. Taurine effect is reduced where heteromeric channels contain Cx32 > Cx26 and eliminated when channels contain only Cx32. Connexin channel stoichiometry, permeability, and chemical gating character change in precisely the desired fashion after parturition to maximize molecular and electrical coupling to support coordinated milk secretion.

Adult↗

PubMed2004

Pituitary-gonadal axis and secondary sex characters in the spontaneously masculinized pintail, Anas acuta (Anatidae, Aves), with special regard to the gonadotrophs.

This paper describes some aspects of the pituitary gland, gonads, and secondary sex characters of unusual pintails, Anas acuta, found in the wild. They were demonstrated to be females with partially masculinized plumage; i.e., their plumage showed various degrees of intersex, but the genital organs, syrinx, and electrophoretic pattern of sex-specific DNA were of the female type. Their left ovary underwent a marked involution and was associated with the mesonephros (the Wolffian body), as was the degenerated right ovary. Neither testicular tissue nor ovotestis was found in the gonad of either side. The oviduct was anatomically normal and comparable to that of the control adult. The plasma concentration of estradiol-17beta (E2) was shown to be 5.7+/-0.5 (mean+/-SE)pg/ml in the masculinized birds, 7.0+/-0.7 pg/ml in control males, and 22.5+/-6.1 pg/ml in control females, whereas plasma testosterone (T) was below the detection level in all of the samples. As to the pituitary gland, hypertrophy and/or deformity of the pars distalis was evident in the majority of the masculinized birds. Among others, hyperactive gonadotrophs, mainly luteinizing hormone (LH)- and LH/follicle-stimulating hormone (FSH)-immunoreactive cells, were prominent in the entire gland; and typical signet ring cells (castration cells) or giant gonadotrophs were frequently observed. These changes in the gonadotrophs may have been caused by a feedback response to the physiologically ovariectomized condition in the masculinized birds. Causal factor(s) of the ovarian degeneration remain to be further investigated.

Animals↗

PubMed2004

Molecular phylogeny of the Pertusariaceae supports secondary chemistry as an important systematic character set in lichen-forming ascomycetes.

The Pertusariaceae is a diverse, cosmopolitan group of crustose lichen-forming fungi. It is particularly rich in secondary metabolites, containing a variety of compounds from different substance classes, such as xanthones, depsides, depsidones, and depsones. Morphology and chemistry-based studies have provided conflicting views of relationships among taxa, and phylogenetic relationships among genera in the Pertusariaceae are still unsettled. To evaluate these relationships, we generated a phylogeny based on nucleotide sequences of the nuclear large subunit (nu LSU) and the mitochondrial small subunit (mt SSU) rRNA genes. For a subset of taxa, we additionally sequenced the mitochondrial large subunit (mt LSU) rDNA. We studied a total of 49 taxa from the family Pertusariaceae and the enigmatic genus Loxosporopsis including four Agyrialean taxa used as outgroups. The alignments were analyzed using a Bayesian approach with Markov Chain Monte Carlo tree sampling (B/MCMC), and maximum parsimony methods. In the resulting phylogenetic estimates the genus Pertusaria in its current circumscription is polyphyletic comprising three major clades: the Pertusaria s.str.-group, the Variolaria-group and the Varicellaria-group. Loxosporopsis is closely related to Pertusaria s.str. We re-analyzed morphological, anatomical, and chemical features in the light of the molecular study and found novel character combinations to describe monophyletic entities. The taxonomic significance of particular secondary chemical constituents in the Pertusariaceae is corroborated.

Ascomycota↗

PubMed2004

Phylogeny of Coreopsideae (Asteraceae) using ITS sequences suggests lability in reproductive characters.

Relationships among the 21 genera within the tribe Coreopsideae (Asteraceae) remain poorly resolved despite phylogenetic studies using morphological and anatomical traits. Recent molecular phylogenies have also indicated that some Coreopsideae genera are not monophyletic. We used internal transcribed spacer (ITS) sequences from representatives of 19 genera, as well as all major lineages in those genera that are not monophyletic, to examine phylogenetic relationships within this group. To examine the affects of alignment and method of analysis on our conclusions, we obtained alignments using five different parameters and analyzed all five alignments with distance, parsimony, and Bayesian methods. The method of analysis had a larger impact on relationships than did alignments, although different analytical methods gave very similar results. Although not all relationships could be resolved, a number of well-supported lineages were found, some in conflict with earlier hypotheses. We did not find monophyly in Bidens, Coreopsis, and Coreocarpus, though other genera were monophyletic for the taxa we included. Morphological and anatomical traits which have been used previously to resolve phylogenetic relationships in this group were mapped onto the well-supported nodes of the ITS phylogeny. This analysis indicated that floral and fruit characters, which have been used extensively in phylogenetic studies in the Coreopsideae, show a higher degree of evolutionary lability in this group than the more highly conserved vegetative and photosynthetic traits.

Asteraceae↗

PubMed2005

Speculation with spiculation?--Three independent gene fragments and biochemical characters versus morphology in demosponge higher classification.

Demosponge higher-level systematics is currently a subject of major changes due to the simplicity and paucity of complex morphological characters. Still, sponge classification is primarily based on morphological features. The systematics of the demosponge order Agelasida has been exceptionally problematic in the past. Here, we present the first molecular phylogenetic analysis based on three partially independent genes in demosponges in combination with a comprehensive search for biochemical synapomorphies to indicate their phylogenetic relationships. We show how sponges with fundamentally different skeletons can be in fact closely related and discuss examples of the misleading nature of morphological systematics in sponges.

Animals↗

PubMed2006

Phylogenetic relationships among the baleen whales based on maternally and paternally inherited characters.

Phylogenetic relationships in the Cetacean suborder Mysticeti (baleen whales) have recently been the focus of increased attention. Here, we examine the evolutionary history of this group by comparing genealogies derived from Y chromosome and mitochondrial DNA sequences. We generated topologies based on paternally and maternally inherited characters for males from nine baleen whale species, including representatives of three families (Balaenidae, Eschrichtiidae, and Balaenopteridae) and four genera (Balaena, Eschrichtius, Balaenoptera, and Megaptera). Divergence among species was fifteen times greater for mtDNA than for Y-specific DNA. Both mtDNA and yDNA topologies revealed the family Balaenopteridae to be paraphyletic, but this relationship was neither strongly supported nor consistent across phylogenetic analysis methodologies. Humpback and fin whales, representing different genera, were reciprocally monophyletic sister species according to mtDNA. Although the monophyly of fin whales decayed for yDNA, a close relationship between fin and humpback whales was retained in yDNA trees. The paraphyly of fin whales and the long branch leading to humpback whales for the yDNA marker may suggest life history differences between these species. Specifically, male humpback whales showed higher than average divergence from other baleen whales at yDNA, although not at mtDNA, suggesting a potential for smaller effective population sizes among male humpbacks on an evolutionary timescale. The observation that those species that have been found to hybridize in nature (blue/fin and blue/humpback) do not reveal evidence for paraphyly for either maternal or paternal markers suggests that introgressive hybridization has not historically been extensive and thus may not represent a substantial source of phylogenetic error for Mysticeti.

Animals↗

PubMed2001

A compatible chord code for inputting elements of Chinese characters.

A compatible chord code for inputting elements of Chinese characters (ECC) to computer was proposed. It capitalized on the graphic compatibility between ECC and chord combination of keys (CCK) on a single-handed chord keyboard with five keys. Experimental results showed that the proposed compatible chord code was better than a code that randomly mapped ECC onto CCK with respect to learning time and response time. Explicit indication of the graphic compatibility between ECC and CCK did not enhance memorizing the compatible code.

Adolescent↗

PubMed1976

Implications of the monoclonal character of human atherosclerotic plaques.

The evidence for the monoclonal nature of human atherosclerotic plaques is briefly reviewed. The interpretation of the cellular monotypy found in a large percentage (75 to 80%) of discrete raised atherosclerotic plaques as being monoclonal in origin appear firm since the size of patches of cells of the same type appears to be very small (ca. 10(-4) cu mm and 10 +/- cells). Evidence for explanations other than single cell origins of each plaque do not appear, at the moment, to be compelling. If we assume then that there is reason to accept the monoclonal character of atherosclerotic plaques in human beings then we are led to a search for the presence of factors that could "initiate" the monoclonal proliferation as well as factors that may promote the growth of the plaques. Evidence is presented that increased risk of atherosclerosis found with cigarette smoking is due to absorption from the lung and circulation in the blood of aryl hydrocarbons. Experiments show that these are preferentially carried in the same parts of the serum that transport cholesterol. The possibility of intrinsic initiators derived from cholesterol is discussed. A possible mechanism for the role of hypertension in promoting atherosclerosis is considered. Finally the evidence for a possible role of viruses in the pathogenesis of atherosclerosis is discussed.

Arteriosclerosis↗

PubMed2000

Chinese and Americans see opposite apparent motions in a Chinese character.

The perceived direction of apparent motion can be influenced by both "top-down" factors, such as expectation, and by "bottom-up" or stimulus-driven factors, such as grouping (Tse, P., Cavanagh, P. & Nakayama, K. (1998). The role of parsing in high-level motion processing. In T. Watanabe, High-level motion processing - computational, neurobiological and psychophysical perspectives. Cambridge, MA: MIT Press). Here we report the results of a single experiment that pitted top-down cues against bottom-up cues in an apparent motion sequence over the successive strokes of a Chinese character. Although each stroke was in fact presented all at once, subjects raised in China tended to see apparent motion over a single stroke in the direction it would have taken when drawn by hand, even though bottom-up cues drive a percept of apparent motion in the opposite direction for observers unfamiliar with the Chinese language. There is therefore a learned component to motion perception arising from top-down expectations capable of overriding bottom-up cues to motion.

Adult↗