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21.
Recent advances suggest that neurons of the anterior intraparietal area play a critical role in the visual guidance of hand action. The parietal cortex appears to process in-coming binocular visual signals of the three-dimensional features of objects and matches these signals with the motor signals, which come from the ventral premotor cortex, that will be required for hand manipulation of the object. 相似文献
22.
Globular proteins have high packing densities as a result of residue side chains in the core achieving a tight, complementary packing. The internal packing is considered the main determinant of native protein structure. From that point of view, we present here a method of energy minimization using an automata network to predict a set of amino acid sequences and their side-chain conformations from a desired backbone geometry for de novo design of proteins. Using discrete side-chain conformations, that is, rotamers, the sequence generation problem from a given backbone geometry becomes one of combinatorial problems. We focused on the residues composing the interior core region and predicted a set of amino acid Sequences and their side-chain conformations only from a given backbone geometry. The kinds of residues were restricted to six hydrophobic amino acids (Ala, Ile, Met, Leu, Phe, and Val) because the core regions are almost always composed of hydrophobic residues. The obtained sequences were well packed as was the native sequence. The method can be used for automated sequence generation in the de novo design of proteins. © 1994 Wiley-Liss, Inc. 相似文献
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Jerzy K. Kulski Silvana Gaudieri Matthew Bellgard Lois Balmer Keith Giles Hidetoshi Inoko Roger L. Dawkins 《Journal of molecular evolution》1997,45(6):599-609
Sequence analysis of a 237 kb genomic fragment from the central region of the MHC has revealed that the HLA-B and HLA-C genes
are contained within duplicated segments peri-B (53 kb) and peri-C (48 kb), respectively, and separated by an intervening
sequence (IF) of 30 kb. The peri-B and peri-C segments share at least 90% sequence homology except when interrupted by insertions/deletions
including Alu, L1, an endogenous retrovirus, and pseudogenes. The sequences of peri-B, IF, and peri-C were searched for the
presence of Alu elements to use as markers of evolution, chromosomal rearrangements, and polymorphism. Of 29 Alu elements,
14 were identified in peri-B, 11 in peri-C, and 4 in IF. The Alu elements in peri-B and peri-C clustered phylogenetically
into two clades which were classified as ``preduplication' and ``postduplication' clades. Four Alu J elements that are shared
by peri-B and peri-C and are flanked by homologous sequences in their paralogous locations, respectively, clustered into a
``preduplication' clade. By contrast, the majority of Alu elements, which are unique to either peri-B or peri-C, clustered
into a postduplication clade together with the Alu consensus subfamily members ranging from platyrrhine-specific (Spqxcg)
to catarrhine-specific Alu sequences (Y). The insertion of platyrrhine-specific Alu elements in postduplication locations
of peri-B and peri-C implies that these two segments are the products of a duplication which occurred in primates prior to
the divergence of the New World primate from the human lineage (35–44 mya). Examination of the paralogous Alu integration
sites revealed that 9 of 14 postduplication Alu sequences have produced microsatellites of different length and sequence within
the Alu 3′-poly A tail. The present analysis supports the hypothesis that HLA-B and HLA-C genes are products of an extended
segmental duplication between 44 and 81 million years ago (mya), and that subsequent diversification of both genomic segments
occurred because of the mobility and mutation of retroelements such as Alu repeats.
Received: 21 May 1997 / Accepted: 9 July 1997 相似文献
26.
Dendrocacalia crepidifolia Nakai (Compositae, Senecioneae), the only species of this arboreal genus endemic to Haha Island in the Bonin Islands, was
found to be dioecious. Male flowers differ from female ones in having a stunted style (style in female exserted from corolla
and deeply bifurcating) and anthers filled with fertile pollen (anthers in the female lacking pollen). The size of the corolla
and number of florets per head were similar between male and female flowers. The crown area of this arboreal species was also
similar in male and female plants. The sex ratio was 0.55 male, not significantly different from 0.5. Both sexes produced
nectar of similar sugar concentration (ca. 50%). The flowers are pollinated by feral honeybees (Apis mellifera), but they are thought to have been pollinated by small, lesshairy, endemic solitary bees before honeybees were introduced
and subsequently became the dominant bee species on the island. The evolution of dioecy ofDendrocacalia on the island is thought to stem from the deleterious effects of inbreeding that are inherent in plants with geitonogamy.
The increased geitonogamy on the island has resulted from increased woodiness (i.e., increased number of flowers per plant)
and the original dependence on endemic bee pollinators, which are now endangered. 相似文献
27.
S Nakamura S Sakata T Komaki N Kojima K Kamikubo S Miyazaki K Yasuda H Tsukada S Shiraki K Miura 《Endocrinologia japonica》1984,31(6):675-679
We measured the levels of serum thyroglobulin (Tg) in 52 pregnant females at various stages and compared them with those of 15 age-matched nonpregnant females. Serum Tg was measured by a solid-phase immunoradiometric assay. In pregnant females, mean serum Tg levels at the first, second, early third, and late third trimesters were 8.4 (range; 1.3-18.0), 9.2 (1.7-25.6), 10.1 (1.8-22.8), and 12.1 ng/ml (5.3-25.2), respectively. The statistical comparison was made after logarithmic transformation of the data. The mean value only at the late third trimester was significantly higher than that of controls (mean; 6.0 ng/ml, range; 1.5-23.6), but each value was within the normal range. Although serum Tg levels have been reported to be high at the end of pregnancy, our results indicate that the Tg levels in females could be clinically interpreted without regard to the coexistence of pregnancy. 相似文献
28.
S. Takagi H. Sakata T. Yoshida K. Den T.K. Fujii H. Amemiya M. Tomita 《Prostaglandins & other lipid mediators》1978,15(5)
ONO-802 was used in the form of vaginal suppositories for the termination of early pregnancy in 63 healthy volunteers. Fifty-four (86%) of the 63 cases had complete abortions and remaining 9 (14%) had incomplete abortions.One (1.6%) of the 63 cases complained of nausea and vomiting, and 3 (4.8%) complained of headaches. No other side effects were observed.These results suggest that ONO-802 is acceptable in the form of vaginal suppositories for the termination of early pregnancy. 相似文献
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TheLyb-2 locus responsible for the B-lymphocyte alloantigen system Lyb-2 is located on chromosome 4 at a distance of 20.6±4.9 map units fromPgm-2. A three-point cross indicated the orderLyb-2: Mup-1b Pgm-2. 相似文献