The E beta hot spot of recombination in wild-derived natural recombinant MHC haplotypes. Cross-over site mapping and the identification of a 1.0-kb E beta deletion in the p and w14 haplotypes

Detailed molecular analysis of three wild-derived MHC haplotypes provided evidence for an important role of the E beta recombinational hot spot in the recent evolution of the mouse I region. Examination of RFLP and restriction maps of cloned DNA permitted the mapping of the natural cross-over events in the haplotypes carried by strains B10.GAA37 (w21) and B10.KPB128 (w19) to a fragment of DNA not exceeding 4.1 kb, which lies almost entirely within the intron separating the beta 1 and beta 2 exons of the E beta gene. In the w14 haplotype (strain B10.STC77), which appears to be a natural recombinant between a p-like parental haplotype and another wild-derived haplotype, the site of crossing over can be mapped to a segment between the beta 2 exon of the E beta gene (left border) and the E beta 2 gene (right border). This segment containing the cross-over site in the w14 haplotype includes the E beta hot spot. In addition, the w14 haplotype as well as the standard p haplotype contain a deletion of approximately 1.0 kb in the second intron of the E beta gene, which may represent the product of an unequal cross-over event in a E beta recombinational hot spot.     

酪氨酸对大鼠子宫胞浆雌,孕激素受体的影响

采用放射受体分析法,测定了动情周期不同阶段及去卵巢大鼠子宫胞浆雌二醇和孕酮受体含量,并观察了子宫腔内注射酪、丝、苏三种氨基酸对子宫胞浆雌。醇、孕酮受体含量的影响。结果表明：（１）Ｌ－酪氨酸对动情前期、动情期、间情期大鼠子宫胞浆雌二醇和孕酮受体都具有明显的降低作用。（２）Ｌ－酪氨酸也降低去卵巢大鼠子宫胞浆雌二醇和孕酮含量,即这一作用不是通过影响卵巢激素分泌实现的。（３）Ｌ－苏氨酸仅可降低动情期和间情期大鼠子宫胞浆孕酮受体含量,而对相应周期雌二醇受体没有明显作用。（４）Ｌ－丝氨酸和Ｌ－苏氨酸对去卵巢大鼠子宫胞浆雌二醇和孕酮受体均无影响。     

Opalinidae in African Anura. III. Genus Cepedea

During 1988 and 1989, 409 specimens of southern African Anura comprising 50 species in 9 families were checked for opalinids in the cloaca. Cepedea acuta n. sp. was found in six of 19 Tomopterna cryptotis and four of seven T. krugerensis (Ranidae); C. affinis (Nazaretskaja, 1992) in two of four Afrixalus aureus, two of four Hyperolius horstocki, 23 of 42 H. marmoratus, one of seven H. pusillus, two of six H. semidiscus, and eight of 12 H. tuberilinguis (Hyperoliidae); C. magna Metcalf, 1923 in one of 20 Bufo garmani, eight of 33 B. gutturalis and two of nine B. rangeri (all Bufonidae), one of two Heleophryne natalensis (juveniles) (Heleophrynidae), four of six Kassina maculata, three of seven K. senegalensis and two of six Semnodactylus wealii (all Hyperoliidae), three of five Phrynomerus bifasciatus (Microhylidae), three of 12 Phrynobatrachus natalensis, 11 of 19 Tomopterna cryptotis, 13 of 14 T. delalandii, one of seven T. krugerensis and one of six T. natalensis (all Ranidae), and four of five Chiromantis xerampelina (Rhacophoridae); Cepedea vanniekerkae n. sp. in one of 19 Tomopterna cryptotis. It is suggested that the Ranidae (in particular the genus Tomopterna) and the Hyperoliidae (in particular the genus Hyperolius) are among the major carriers of Cepedea in the Afrotropical Region.     

Determination of trimethoprim in bovine serum by high-performance liquid chromatography with confirmation by thermospray liquid chromatography—mass spectrometry

A high-performance liquid chromatographic (HPLC) method with a detection limit of 5 ng/ml was developed for the analysis of trimethoprim in bovine serum. Trimethoprim and the internal standard, ormetoprim, under alkaline conditions, were first extracted into dichloromethane and then back-extracted into dilute sulphuric acid (0.15 M) and cleaned-up on a C₁₈ cartridge. Trimethoprim was quantified on a C₁₈ column using a triethylammonium acetate—acetonitrile—methanol (16:3:1, v/v/v) mobile phase at a flow-rate of 1.5 ml/min, with ultraviolet detection at 225 nm. This method was used to verify the accuracy of test responses obtained with the Brilliant Black Reduction test, a rapid screening method, for trimethoprim levels in the serum of steers treated with Trivetrin. Confirmation of the presence of trimethoprim in the sample extract was obtained by thermospray HPLC—mass spectrometry.     

人胚DA能神经元移植于帕金森氏病猴模型的TH免疫细胞化学的研究

为了对人胚黑质ＤＡ神经元移植治疗ＰＤ人的临床应用作出客观评估,将８－１２周人胚黑质细胞移植到用ＭＰＴＰ诱发的偏侧ＰＤ猴新纹状体内。实验动物分别存活２个月、５个月和１年后,用ＴＨ免疫细胞化学方法对被移植的人胚ＤＡ细胞的存活和与宿主间的突触联系进行检查。在光镜下可见被移植侧的新纹状体内有ＴＨ阳性细胞,它们成小群散在分布,每小群有３－１０个细胞。ＴＨ阳性细胞的轴突延伸到整个新纹状体,树突呈现出正常发育过     

Phonotaxis in the painted reed frog (Hyperolius marmoratus)

Summary A detailed study was conducted of the three-dimensional accuracy of phonotaxis by femaleHyperolius marmoratus. This analysis involved videotape recordings of phonotactic approaches to an elevated loudspeaker through a three-dimensional grid. Females readily resolved the sound source elevation, but the jump error angles describing the precision of approach were considerably greater in this three-dimensional analysis than in the more conventional two-dimensional ground approach analysis. Extensive use was made of visual cues in elevated phonotactic approach and lateral head scanning prior to jumps, often accompanied by vertical changes in head orientation, was frequent. The ability of such small anurans to localize a sound source in both the horizontal and vertical plane is remarkable.On leave from the Section of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853, USA     

Genetic control of acquired resistance to visceral leishmaniasis in mice

A series of H-2 and non-H-2 congenic resistant (CR) strains on a C57BL/10Sn background were infected with 10(7) amastigotes of Leishmania donovani. Non-H-2 congenic strains B10.LP-H-3b and B10.CE(30NX) and (B10.LP-H-3b x B10)F1 hybrids showed a very rapid decrease in liver-parasite burdens beyond day 21. Parasite counts for these strains at day 35 were significantly lower than for all other strains tested. The rapid decrease in parasite numbers, massive lymphocellular infiltration into the liver and strong delayed hypersensitivity reactions to parasite antigens in strains congenic for a portion of chromosome 2 indicated that acquired immunity to L. donovani was controlled by a dominant gene at or near the Ir-2 locus. In addition, B10.129(10M) mice, which differ from C57BL/10Sn at the H-11 locus, showed highly significant increases in parasite numbers at day 35. Other observations supporting the absence of acquired immunity in B10.129(10M) included negative delayed hypersensitivity tests to parasite antigens and the absence of lymphocellular infiltrate into the liver. Although the differences were not as pronounced, H-2 CR strains with H-2b, H-2a, and H-2k haplotypes also showed significantly greater decreases in parasite numbers by day 35 as compared to other H-2 CR strains.     

Cardiac allografts in mice congenic at non-H-2 histocompatibility loci

Neonatal mouse heart fragments were grafted under the ear skin of adult recipients. Cardiac allograft survival was evaluated by visual observation of pulsation, electrocardiography, and histology. Employing a series of congenic resistant strains differing from C57BL/10Sn at theH-1, H-3,H-4, H-7, H-8, H-9, H-10, H-11, andH-12 loci, the median survival times of the heart grafts to and from C57BL/10Sn were obtained. The various interallelic combinations resulted in a wide variation of graft survival. Reciprocal transplants frequently showed different survival times.H-1 ^c grafts were rejected by B10.129(5M)/nSn female mice with a median survival time of 90 days.H-1 ^b grafts were not rejected by C57BL/10Sn mice for the experiment's duration of 200 days. The weaker the histocompatibility barrier, the more variable the survival times and the smaller the ratio of rejected to total grafted heart fragments. Female recipients were observed to reject their grafts more rapidly and to reject a higher proportion than males of the same strain. Although the strength of the different non-H-2 barriers generally paralleled that determined by skin transplants, the rankings of the strongest minor barriers were not the same for both tissues.