RFLP-based maps of the homoeologous group-6 chromosomes of wheat and their application in the tagging of Pm12, a powdery mildew resistance gene transferred from Aegilops speltoides to wheat

Genetic maps of the homoeologous group-6 chromosomes of bread wheat, Triticum aestivum, have been constructed spanning 103 cM on 6A, 90 cM on 6B and 124 cM on 6D. These maps were transferred to a Chinese Spring (CS) x line #31 cross to locate a dominant powdery mildew resistance gene, Pm12, introgressed into line #31 from Aegilops speltoides. Pm12 was shown to lie on the short arm of translocation chromosome 6BS-6SS.6SL in line #31, but could not be mapped more precisely due to the lack of recombination between the 6S Ae. speltoides segment and chromosome 6B. Possible strategies to reduce the size of the alien segment, which probably encompasses the complete long arm and more than 82% of the short arm of chromosome 6B, are discussed.     

RFLP mapping of partially sequenced leaf cDNA clones in maize

We report here the results of mapping a set of 92 leaf cDNA clones in maize. The ends of each of these cDNA clones have previously been partially sequenced, and the sequence comparison has revealed the putative function for 28 clones. It is expected that the RFLP map developed using these expressed sequence tags will be of great importance for future maize genome analysis, such as for PCR-based gene mapping or gene function identification.Contribution from the Missouri Agricultural Experiment Station. Journal Series N. 12,019.     

黑龙江依兰早第三纪植物群的古气候分析

对黑龙江依兰煤矿煤层间的大量植物叶痕化石研究表明：依兰植物群有蕨类植物２ 种,裸子植物１０ 种,被子植物５８ 种,分属３４ 科４６属。植物群可分为两个植物组合：一个是下煤层上顶板的矿页岩层化石的组合,称Ａ 段组合,时代为早始新世。植物种类丰富,含有较多常绿阔叶成分,属北亚热带的常绿阔叶和落叶阔叶、针阔叶混生林。通过植物叶相特征分析,其全缘叶比例为３８％ 。用气候诺模图得出其古气候为年均温１３．２℃,年温差２０℃;另一个植物组合是煤系地层之上,即上煤层顶部的油页岩层中的Ｂ段化石组合,时代为早渐新世。植物以落叶成分为主,属暖温带落叶阔叶林和针阔叶混生林。全缘叶比例为３０％ 。古气候年均温为１１℃,年温差２５℃。表明植物区系组成完全不同,显示出气候随时代发生了演变,而使区系逐渐发展到今日的寒温带气候和植被     

Two genes present on a transposon-like structure in Lactococcus lactis are involved in a Clp-family proteolytic activity

The lactose-protease plasmid pUCL22 of Lactococcus lactis subsp. lactis strain CNRZ270 contained two inverted copies of IS 1076 flanking a region of 3.7 kb. This internal region was sequenced and found to contain two large open reading frames, ORF1 and ORFP in opposite orientations. ORF1 consists of 2289 bp; the deduced 763-amino-acid sequence is similar to the ATPases of the ClpA family. It contains two well-conserved consensus ATP-binding sites. It was named ClpL. ORFP consists of 930 bp encoding a protein of 310 amino acids. No similarity with any known protein was found in GenBank data for ORFP. Increased ATP-dependent proteolytic activity was detected in extracts from Escherichia coli cells expressing the clpL and ORFP genes.     

PDGF-AA activates AKT and ERK signaling for testicular interstitial Leydig cell growth via primary cilia

Testes control the development of male reproductive system. The testicular interstitial Leydig cells (Leydig cells) synthesize testosterone for promoting spermatogenesis and secondary sexual characteristics. Type A platelet-derived growth factor (PDGF-AA) is one of the most important growth factors in regulating Leydig cell growth and function. Knockout of PDGF-AA or its congenital receptor PDGFR-α leads to poor testicular development caused by reducing Leydig cell numbers, supporting PDGF-AA/PDGFR-α signaling regulates Leydig cell development. Primary cilium is a cellular antenna that functions as an integrative platform to transduce extracellular signaling for proper development and differentiation. Several receptors including PDGFR-α are observed on primary cilia for initiating signaling cascades in distinct cell types. Here we showed that PDGF-AA/PDGFR-α signaling promoted Leydig cells growth, migration, and invasion via primary cilia. Upon PDGF-AA treatment, AKT and ERK signaling were activated to regulate these cellular events. Interestingly, active AKT and ERK were detected around the base of primary cilia. Depletion of ciliary genes (IFT88 and CEP164) alleviated PDGF-AA-activated AKT and ERK, thus reducing Leydig cell growth, migration, and invasion. Thus, our study not only reveals the function of PDGF-AA/PDGFR-α signaling in maintaining testicular physiology but also uncovers the role of primary cilium and downstream signaling in regulating Leydig cell development.     

Aberrant Gag protein composition of a human immunodeficiency virus type 1 vif mutant produced in primary lymphocytes.

Productive, spreading infection of peripheral blood lymphocytes (PBL) with human immunodeficiency virus type 1 (HIV-1) requires the viral protein Vif. To study the requirement for vif in this system, we infected PBL with a phenotypically complemented HIV-1 clone mutated in vif. Progeny virus was produced which was noninfectious in PBL but replicated in SupT1 cells. Analysis of metabolically labeled proteins of sedimentable extracellular particles made in PBL by radioimmunoprecipitation with either serum from a patient with AIDS or a monoclonal antibody reactive with HIV-1 Gag proteins revealed that vif-negative but not wild-type particles carry higher levels of p55, p41, and p38 Gag-specific proteins compared with those of p24. Similar results were obtained with sucrose-purified virions. Our data indicate that vif plays a role in Gag protein processing or in incorporation of processed Gag products into mature virions. The presence of unprocessed precursor Gag polyprotein (Pr55gag) and other Gag processing intermediates in PBL-derived vif-negative extracellular particles may contribute to the reduced infectivity of this virus.     

Kallikrein activation of a high molecular weight atrial peptide

Mammalian atrial extracts contain bioactive peptides that exert profound effects upon renal function and isolated smooth muscle preparations. Gel filtration chromatography of rat atrial extract separates the activity into two peaks having apparent molecular weights of 20,000 to 30,000 and less than 10,000. Mild proteolytic treatment (trypsin 1 U/ml) of the high molecular weight fraction enhances the smooth muscle relaxant activity of this fraction and concomitantly reduces the apparent molecular weight of this fraction to less than 10,000. In this report we show that urinary and submaxillary kallikrein enhances the activity of rat atrial extracts in a similar fashion. Pretreatment of the high molecular weight fraction with either kallikrein (1 microgram/ml) enhances the smooth muscle relaxant activity of this fraction. Similar treatment of the low molecular weight fraction had no effect. The enhancement of the bioactivity of the high molecular weight substance(s) by the kallikreins was abolished by aprotinin but was unaffected by soybean trypsin inhibitor. These results suggest that exogenous addition of tissue kallikrein activates a high molecular weight peptide by limited proteolysis. Analysis of the kallikrein-treated high molecular weight peptide fraction by gel filtration indicates that the biological activity comigrates with the low molecular weight peptides present in the original atrial extract.     

The effect of nitroimidazoles on glucose utilization and lactate accumulation in mouse brain

The radiation sensitizers misonidazole (MISO) and desmethylmisonidazole (DMM) can produce central and peripheral neuropathy in patients and laboratory animals. Behavioral and pathological investigations have indicated that in the central nervous system this primarily involves the cochlear and vestibular systems. Nitroimidazoles can also interfere with glycolysis in vitro under aerobic and anaerobic conditions. In the present work we have studied the effect of MISO or DMM on lactate production and glucose utilization in mouse brain. It is observed that these compounds result in a 25% inhibition of lactate production in brain slices relative to the control at a 10 mM level. Additionally, MISO (1.0 mg/g/day) or DMM (1.4 mg/g/day) were administered daily (oral) for 1, 4, 7, or 14 days to examine the effect of these two drugs on the regional glucose utilization in C3Hf mouse brain. Five microcuries of 2-deoxy[14C]glucose was given following the last drug dose and autoradiographs of serial brain sections were made and analyzed by a densitometer. Following a single dose of either MISO or DMM, no significant differences in glucose uptake were observed when compared with controls. However, following 4, 7, and 14 doses the rate of glucose utilization was significantly reduced in the intoxicated animals. Larger reductions were measured in specific regions including the posterior colliculus, cochlear nuclei, vestibular nuclei, and pons with increasing effects observed at later stages. These results share a degree of correspondence with the regional brain pathology produced by these nitroimidazoles.