Buccal capsule development as a consideration for phylogenetic analysis of Rhabditida (Nemata)

Bacterial feeding nematodes in the order Rhabditida including Zeldia punctata (Cephalobidae) and Caenorhabditis elegans (Rhabditidae) differ profoundly in the buccal capsule parts and associated cells. We carried out a range of tests to determine which buccal capsule parts and cells are evolutionarily homologous between the representative species of the two families. Tests included reconstruction of the buccal capsule and procorpus with transmission electron microscopy (TEM), nuclei position and morphology using 4, 6-diamidino-2-phenylindole (DAPI) staining, and cell lineage using four dimensional (4D) microscopy. The lining of the buccal capsule of Z. punctata and additional Cephalobidae includes four sets of muscular radial cells, ma, mb, mc and md, in contrast to C. elegans and additional Rhabditidae, which has two sets of epithelial cells (e1, e3) and two sets of muscle cells (m1, m2). Cell lineage of a nematode closely related to Z. punctata, Cephalobus cubaensis, supports the hypothesis that in cephalobids the e1 and e3 cells become hypodermal cells or are programmed to die. Our findings contradict all previous hypotheses of buccal capsule homology, and suggest instead that ma and mb in Z. punctata are homologous to m1 and m2 in C. elegans respectively. We also hypothesize that ma and mb could be homologous to primary and secondary sets of stylet-protractor muscle cells in the plant parasitic Tylenchida.     

Partial gene sequences for the A subunit of methyl-coenzyme M reductase (mcrI) as a phylogenetic tool for the family Methanosarcinaceae

Representatives of the family Methanosarcinaceae were analyzed phylogenetically by comparing partial sequences of their methyl-coenzyme M reductase (mcrI) genes. A 490-bp fragment from the A subunit of the gene was selected, amplified by the PCR, cloned, and sequenced for each of 25 strains belonging to the Methanosarcinaceae. The sequences obtained were aligned with the corresponding portions of five previously published sequences, and all of the sequences were compared to determine phylogenetic distances by Fitch distance matrix methods. We prepared analogous trees based on 16S rRNA sequences; these trees corresponded closely to the mcrI trees, although the mcrI sequences of pairs of organisms had 3.01 +/- 0.541 times more changes than the respective pairs of 16S rRNA sequences, suggesting that the mcrI fragment evolved about three times more rapidly than the 16S rRNA gene. The qualitative similarity of the mcrI and 16S rRNA trees suggests that transfer of genetic information between dissimilar organisms has not significantly affected these sequences, although we found inconsistencies between some mcrI distances that we measured and and previously published DNA reassociation data. It is unlikely that multiple mcrI isogenes were present in the organisms that we examined, because we found no major discrepancies in multiple determinations of mcrI sequences from the same organism. Our primers for the PCR also match analogous sites in the previously published mcrII sequences, but all of the sequences that we obtained from members of the Methanosarcinaceae were more closely related to mcrI sequences than to mcrII sequences, suggesting that members of the Methanosarcinaceae do not have distinct mcrII genes.     

Latency to categorize disoriented alphanumeric characters as letters or digits.

Previous research has shown that if Ss must decide quickly whether a disoriented alphanumeric character is normal or backward, they "mentally rotate" an internal representation of the character to its normal upright position before making the decision. The present study with 12 undergraduates showed that latency to decide whether a disoriented character was a letter or a digit was barely affected by angular orientation, implying that mental rotation is not necessary for this task. However, latency was significantly shorter for normal than for backward characters, regardless of angular orientation, suggesting that the difference between normal and backward characters does register prior to mental rotation. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spermatozoa selection by the swim-up procedure and two-layer percoll gradient centrifugation

The efficiency of the swim-up procedure and two-layer Percoll gradient centrifugation in procession of spermatozoa was assessed in ejaculates from 47 infertile men. A significantly higher total number of spermatozoa was harvested from Percoll gradients than from the swim-up procedure, the loss rates in concentration being -13.6 +/- 6.4% and -70.8 +/- 5.8%, respectively (p < 0.0001). Recovery in per cent motility was significantly higher after the Percoll gradient than after the swim-up procedure (34.8 +/- 10.2% versus -10.4 +/- 17.2%, p < 0.05). No significant difference was noted between the mean motility grades of the final solutions obtained by the two methods (2.7 +/- 0.2 and 2.0 +/- 0.4, respectively, p > 0.05). When evaluation was conducted within three initial fresh sample concentration categories such as severe oligospermia (lower than 5 x 10(6)/ml), moderate oligospermia (5 to 10 x 10(6)/ml) and mild oligospermia (higher than 10 x 10(6)/ml), the Percoll technique recovered significantly higher number of spermatozoa than the swim-up procedure through all concentration categories (p < 0.05 for each range). Despite being statistically insignificant, Percoll gradients produced final spermatozoa pools with higher per cent motility and motility quality within all concentration ranges. The results suggest that the Percoll gradient centrifugation should be the preferred selection method regardless of the initial fresh sample concentration.     

Big trees from little genomes: mitochondrial gene order as a phylogenetic tool

Mixed acetylboswellic acids, pentacyclic triterpenes extracted from the gum resin of Boswellia serrata Roxb., significantly inhibited the ionophore-stimulated release of the leukotrienes (LT) B4 and C4 from intact human polymorphonuclear neutrophil leukocytes (PMNLs), with IC50 values of 8.48 micrograms/ml and 8.43 micrograms/ml, respectively. Purified acetyl-11-keto-beta-boswellic acid was about three times more potent as inhibitor of the formation of both LTB4 (IC50 = 2.53 micrograms/ml) and LTC4 (IC50 = 2.26 micrograms/ml) from human PMNLs in the same assay. The comparative agent MK 886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]- 2,2-dimethylpropanoic acid, L-663,536, CAS 118, 414-82-7) was about 10 to 100-fold more active than the boswellic acids in inhibiting the formation of 5-lipoxygenase products in human PMNLs, with IC50 values of 0.0068 microgram/ml (LTB4) and 0.49 microgram/ml (LTC4). After daily intraperitoneal dosage the extract of mixed acetylboswellic acids (20 mg/kg) significantly reduced the clinical symptoms in guinea pigs with experimental autoimmune encephalomyelitis (EAE) between days 11 and 21. However, the inflammatory infiltrates in the brain and the spinal cord were not significantly less extensive in the treated animals than in the respective control group. The multiple intraperitoneal application of boswellic acids did not inhibit the ionophore-challenged ex vivo release of leukotrienes B4 and C4 from PMNLs separated from the blood of guinea pigs with EAE. The boswellic acids have thus been characterized as selective, non-redox and potent inhibitors of the biosynthesis of leukotrienes in vitro.     

Further data on the characters of Listeria strains

The composition of a minimal medium suitable for the demands of modern genetical work is described. The nutritional requirements of some 15 strains of L. monocytogenes were studied on this medium. DL-6,8-thioctic acid was not essential. The organisms also grew without thiamine but for a convenient colony size this vitamin had to be used. The presence of Fe++, Mg++, and Ca++ ions as well as a low redox potential supplied by thioglycollate was necessary. There was some difference in the amino acid requirements of the strains. The most common demand was for leucine, iso-leucine, valine, and cysteine. The serotype, agglutinability, hemolytic effect, virulence, and nutritional requirements of the Listeria were compared. It seems that these properties are not consistently linked. Two 'EMS' mutants were also studied. The arginine, glutamine, and methionine metabolism of the auxotrophic mutant 025/4/4 was damaged and its virulence was lost. Data connected with the virulence markers of Listeria are discussed.     

Molecular phylogenetic approach for studying life-history evolution: the ambiguous example of the genus Medicago L

We present a molecular phylogeny including most species of the genus Medicago L. (Fabaceae). Based on the consensus of the 48 most parsimonious trees, life-history and mating-system characters are mapped, and a putative history of the genus is suggested. The most parsimonious reconstruction suggests an ancestral annual and selfing state, and recurrent evolution towards perenniality and outcrossing. Based on theoretical predictions and classical hypotheses of the history of the genus, different assumptions about the ancestral state and different weighting schemes of evolution between the character states are made. Assuming an outcrossing, perennial ancestral state (partly supported by morphological features) does not fundamentally change the reconstruction. To meet theoretical expectations, various weighting schemes favouring evolution towards annuality and selfing are applied. Influence and validity of such weighting schemes are discussed with regard to other studies.     

A phylogenetic assessment of the eukaryotic light-harvesting antenna proteins, with implications for plastid evolution

Stimulation of cutaneous foot afferents has been shown to evoke a facilitation of the tibialis anterior (TA) EMG-activity at a latency of 70-95 ms in the early and middle swing phase of human walking. The present study investigated the underlying mechanism for this facilitation. In those subjects in whom it was possible to elicit a reflex during tonic dorsiflexion while seated (6 out of 17 tested), the facilitation in the TA EMG evoked by stimulation of the sural nerve (3 shocks, 3-ms interval, 2.0-2.5x perception threshold) was found to have the same latency in the swing phase of walking. The facilitation observed during tonic dorsiflexion has been suggested to be -- at least partly -- mediated by a transcortical pathway. To investigate whether a similar mechanism contributes to the facilitation observed during walking, magnetic stimulation of the motor cortex (1.2x motor threshold) was applied in the early swing phase at different intervals in relation to the cutaneous stimulation in 17 subjects. In 13 of the subjects, the motor potentials evoked by the magnetic stimulation (MEPs) were more facilitated by prior sural-nerve stimulation (conditioning-test intervals of 50-80 ms) than the algebraic sum of the control MEP and the cutaneous facilitation in the EMG when evoked separately. In four of these subjects, a tibialis anterior H-reflex could also be evoked during walking. In none of the subjects was an increase of the H-reflex similar to that for the MEP observed. In five experiments on four subjects, MEPs evoked by magnetic and electrical cortical stimulation were compared. In four of these experiments, only the magnetically induced MEPs were facilitated by prior stimulation of the sural nerve. We suggest that a transcortical pathway may also contribute to late cutaneous reflexes during walking.     

EMS-induced polygenic mutation rates for nine quantitative characters in Drosophila melanogaster

Polygenic mutations were induced by treating Drosophila melanogaster adult males with 2.5 mM EMS. The treated second chromosomes, along with untreated controls, were then made homozygous, and five life history, two behavioral, and two morphological traits were measured. EMS mutagenesis led to reduced performance for life history traits. Changes in means and increments in genetic variance were relatively much higher for life history than for morphological traits, implying large differences in mutational target size. Maximum likelihood was used to estimate mutation rates and parameters of distributions of mutation effects, but parameters were strongly confounded with one another. Several traits showed evidence of leptokurtic distributions of effects and mean effects smaller than a few percent of trait means. Distributions of effects for all traits were strongly asymmetrical, and most mutations were deleterious. Correlations between life history mutation effects were positive. Mutation parameters for one generation of spontaneous mutation were predicted by scaling parameter estimates from the EMS experiment, extrapolated to the whole genome. Predicted mutational coefficients of variation were in good agreement with published estimates. Predicted changes in means were up to 0.14% or 0.6% for life history traits, depending on the model of scaling assumed.     

检测机构对标准文献需求的特征及应对措施

标准文献有其明显特征,是标准化工作的一个重要组成部分,它是检测机构工作依据和工具。提出了标准文献管理要适应检测机构的特点,注重收集的有效性,保证质量管理体系的受控状态,利用现代检索工具及时掌握标准信息动态就显得十分重要。     

Illusory conjunctions in the perception of Chinese characters.

A Chinese compound character consists of a radical component and a stem component. When compound characters were represented briefly, Ss often reported seeing illusory recombinations of radicals and stems. A series of 5 experiments suggested that the probability of seeing illusory characters is not under the direct influence of lexicality, pronounceability, or character frequency, but depends on 2 factors: (1) familiarity defined in terms of unit frequency, i.e., the frequency of occurrence of a unit either by itself or as part of a larger unit, and (2) the context-dependent perceptual distinctiveness of the components of a given character. It is suggested that the seemingly unreliable lexicality effect obtained in English studies may be reduced to a familiarity effect, and that what J. L. McClelland and M. C. Mozer (see record 1986-16293-001) referred to as the surround-similarity effect may be better characterized as an effect of perceptual distinctiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

试论学生的主体性特征及其教育

学生是教学活动的主体，在教学活动中，学生的主体性特征主要表现为个体生命发展的独立自主性、积极能动性和创造超越性。为此，我们必须尊重学生的主体地位，树立主体性教育理念、创新性教育理念和超越性教育理念．促进学生得到充分、自由的发展。     

Sequence and phylogenetic analysis of the Borrelia burgdorferi secA gene

Adamantinoma of long bones is a rare bone tumour with (immuno-) histological features of epithelial cells, surrounded by various amounts of osteofibrous tissue. Recent studies have indicated that cells with an epithelial phenotype are most probably the malignant element. There is still debate as to whether the fibrous part should be designed as a benign neoplastic element of a biphasic tumour or as a reactive non-neoplastic tissue next to an epithelioid bone tumour. The expression of fibroblast growth factor type 2 (FGF-2), epidermal growth factor (EGF), and their respective receptors FGFR-1 and EGFR, as well as the proliferation marker Ki-67, was studied in both constituents of adamantinoma in serial sections of 25 cases by immunohistochemistry. Expression of FGF-2 and its receptor was present in both constituents of adamantinoma, but predominated in the epithelial component. Expression of EGF and its receptor was restricted to the epithelial component of adamantinoma. Comparing osteofibrous dysplasia (OFD)-like adamantinoma with classic epithelial cell-rich adamantinoma, the expression of FGF-2, EGF, and EGFR was more intense and in a higher percentage of cells in classic adamantinoma. Proliferative activity was found nearly exclusively in the epithelial component. These data further substantiate the hypothesis that epithelial cells constitute the proliferating tumour cell population responsible for the malignant behaviour of adamantinoma. The data indicate that during progression, the epithelial cells acquire expression of FGF-2, EGF, and EGFR, accompanied by a higher proliferative activity. Within the epithelial cell population, there exists an autocrine pathway of growth stimulation. Furthermore, these data point to an interaction between the epithelial and fibrous components, in which the epithelial cells additionally stimulate fibrous cell growth via a paracrine pathway involving FGF-2.     

The phylogenetic status of phyllomedusine frogs (Hylidae) as evidenced from immunological studies of their serum albumins

Based on immunological comparisons of the serum albumins of phyllomedusine frogs with both hyline and bufonid species, it is suggested that phyllomedusine frogs be erected to familial status within the superfamily Bufonoidea.