Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis     

Jen JC  Chan WM  Bosley TM  Wan J  Carr JR  Rüb U  Shattuck D  Salamon G  Kudo LC  Ou J  Lin DD  Salih MA  Kansu T  Al Dhalaan H  Al Zayed Z  MacDonald DB  Stigsby B  Plaitakis A  Dretakis EK  Gottlob I  Pieh C  Traboulsi EI  Wang Q  Wang L  Andrews C  Yamada K  Demer JL  Karim S  Alger JR  Geschwind DH  Deller T  Sicotte NL  Nelson SF  Baloh RW  Engle EC 《Science (New York, N.Y.)》2004,304(5676):1509-1513

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.  相似文献   

不同氮素施用量对葡萄叶、枝、根碳水化合物含量的影响   总被引：4，自引：0，他引：4  

克热木·伊力  新居直祐 《新疆农业大学学报》2001,24(1):64-68

本试验用500ml塑料育苗盆定植一年生葡萄扦植苗，研究不同氮素施用量对地上部和地下部生长及碳水化合物含量的影响，并对根尖细胞构造进行了探讨，结果表明：地上部生长量，干物重，叶面积在N-300区最大；全叶绿素含量随氮素施用量的增加而增加，叶淀粉，全糖含量随氮素施用量的增加而降低，枝条和根的淀粉含量在N-75区和N-150区最高，全糖含量在N-150区和N-300区最高，在N-900区最低。生长越旺盛的植株，白色根越多，氮素施用量过多时出现黑色根增多的倾向。  相似文献   

Legionella effectors that promote nonlytic release from protozoa     

Chen J  de Felipe KS  Clarke M  Lu H  Anderson OR  Segal G  Shuman HA 《Science (New York, N.Y.)》2004,303(5662):1358-1361

Legionella pneumophila, the bacterial agent of legionnaires' disease, replicates intracellularly within a specialized vacuole of mammalian and protozoan host cells. Little is known about the specialized vacuole except that the Icm/Dot type IV secretion system is essential for its formation and maintenance. The Legionella genome database contains two open reading frames encoding polypeptides (LepA and LepB) with predicted coiled-coil regions and weak homology to SNAREs; these are delivered to host cells by an Icm/Dot-dependent mechanism. Analysis of mutant strains suggests that the Lep proteins may enable the Legionella to commandeer a protozoan exocytic pathway for dissemination of the pathogen.  相似文献   

Molecular modeling of syringyl and p-hydroxyphenyl beta-O-4 dimers. Comparative study of the computed and experimental conformational properties of lignin beta-O-4 model compounds     

Besombes S  Robert D  Utille JP  Taravel FR  Mazeau K 《Journal of agricultural and food chemistry》2003,51(1):34-42

As a new approach for the study of the ultrastructure of lignin, the conformational preferences of lignin beta-O-4 model compounds have been investigated by molecular modeling. The computed results have been compared with the experimental data (X-ray crystal structures and (3)J(H)(alpha)(H)(beta) NMR coupling constant values) reported in the literature. This comparison has led to an improved understanding of the influence of the structure, stereochemistry, and intramolecular H-bonding upon the conformational properties of the beta-O-4 dimers. A large number of low-energy conformations have been predicted for the structures. It has also appeared that the conformational features are predominantly governed by local steric interactions rather than by differences in the H-bonding interactions. The threo and erythro forms differ significantly in their conformational features, with a preferential extended overall shape for the threo form in which the bulky aromatic groups are distant from each other.  相似文献   

Prevalence of larval taeniids in goats in Bangladesh     

Md. Jahurul Karim  Hefazuddin Shaikh  Md. Mozzammel Huq 《Tropical animal health and production》1982,14(3):166-166

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Pox among sannen goats in Iraq     

M. A. Karim 《Tropical animal health and production》1983,15(1):62-62

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A survey of coenurosis in sheep in northern Iraq     

M A Karim 《Tropical animal health and production》1979,11(3):157-158

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A technique for creating critical-size defects in the metatarsus of sheep for use in investigation of healing of long-bone defects   总被引：2，自引：0，他引：2  

Viateau V  Guillemin G  Yang YC  Bensaid W  Reviron T  Oudina K  Meunier A  Sedel L  Petite H 《American journal of veterinary research》2004,65(12):1653-1657

OBJECTIVE: To develop a technique for use in investigation of healing of long-bone defects by creation of a critical-size defect in the left metarsal III and IV bone (metatarsus) of sheep. ANIMALS: 18 healthy adult sheep. PROCEDURE: Sheep were allocated to 4 groups (3, 3, 5, and 7 sheep in groups 1 to 4, respectively). An ostectomy with various segmental length-to-diaphyseal diameter ratios (0.5, 1.0, 2.0, and 2.0 for groups 1 to 4, respectively) was performed on the left metatarsus of each sheep. The defect was left empty in sheep of groups 1, 2, and 3, whereas the defect was filled with a massive corticocancellous bone autograft in sheep of group 4. RESULTS: All sheep tolerated the surgical procedure well and were able to use the affected limb the day after surgery. Radiographic and histologic examinations conducted 16 weeks after surgery revealed nonunion in all sheep of groups 1, 2, and 3, whereas consistent bone healing with abundant bone formation was observed in all sheep of group 4. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these findings suggests that the sheep metatarsal model is a critical-size defect model with low morbidity. It should allow the assessment of new technologies for bone regeneration in conditions closely mimicking the clinical setting. IMPACT FOR HUMAN MEDICINE: Use of this technique in sheep should be of benefit for the preclinical study of osteoconductive, osteoinductive, or osteogenic biomaterials for use in humans.  相似文献   

An AIDS-free generation?     

SS Abdool Karim 《Science (New York, N.Y.)》2012,337(6091):133

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Level and period of realimentation to assess improvement in body condition and carcass quality in cull ewes     

Randhir Singh Bhatt  Nira Manik Soren  Artabandhu Sahoo  Shaikh Abdul Karim 《Tropical animal health and production》2012,45(1):167-176

Improvement in body condition was assessed in 40 cull ewes (>6 years), equally distributed in two groups and realimented with ad libitum roughage (gram straw) and two levels of concentrate feeding, i.e., 2.5 % (T₁) of live weight (LW) and ad libitum (T₂). Five representative animals from an initial 45 were slaughtered at the initiation of the study (0 day) and five animals from each treatment at 44, 67, and 90 days of experiment for carcass attributes. Improvement in body condition score (BCS), nutrient utilization, feed efficiency, and carcass traits were assessed at 44, 67, and 90 days. Metabolism trial of 6-day collection of feed, feces, and urine samples was conducted on five representative ewes from each group after 60 days of feeding. The level of concentrate feeding on LW gain and BCS was significant, and the duration of realimentation showed a linear improvement (P?<?0.001). The digestibility and intake of dry matter, organic matter, and crude protein was higher (P?<?0.05) in T₂. The N intake, absorption, and balance showed a similar trend. Increase (P?<?0.05) in total N, trichloroacetic acid precipitable N, and ammonia N was observed with extension of realimentation period. Blood metabolic profile also showed improvement (P?<?0.05) from an undernourished state to normal after alimentation. Animals in T₂ accumulated higher LW with minimal expenditure of metabolizable energy (73.4 vs 79.1 MJ) and higher efficiency of feed conversion during 68 to 90 days of realimentation. Linear improvement (P?<?0.01) in carcass traits (preslaughter weight, empty live weight, hot carcass weight, dressing percentage, and amount of subcutaneous and intramuscular fat) and composition of longissimus dorsi muscle was observed. Ad lib concentrate supplementation for a period of 90 days may thus be considered appropriate for achieving desired efficiency of gain and improvement in body condition of cull ewes for quality mutton production.  相似文献