The Syk protein tyrosine kinase can function independently of CD45 or Lck in T cell antigen receptor signaling.

The protein tyrosine phosphatase CD45 is a critical component of the T cell antigen receptor (TCR) signaling pathway, acting as a positive regulator of Src family protein tyrosine kinases (PTKs) such as Lck. Most CD45-deficient human and murine T cell lines are unable to signal through their TCRs. However, there is a CD45-deficient cell line that can signal through its TCR. We have studied this cell line to identify a TCR signaling pathway that is independent of CD45 regulation. In the course of these experiments, we found that the Syk PTK, but not the ZAP-70 PTK, is able to mediate TCR signaling independently of CD45 and of Lck. For this function, Syk requires functional kinase and SH2 domains, as well as intact phosphorylation sites in the regulatory loop of its kinase domain. Thus, differential expression of Syk is likely to explain the paradoxical phenotypes of different CD45-deficient T cells. Finally, these results suggest differences in activation requirements between two closely related PTK family members, Syk and ZAP-70. The differential activities of these two kinases suggest that they may play distinct, rather than completely redundant, roles in lymphocyte signaling.     

Two new loci for hybrid sterility in cultivated rice (Oryza sativa L.)

Female gamete abortion in Indica-Japonica crosses of rice was earlier identified to be due to an allelic interaction at the S-5 locus on chromosome 6. Recently, in other crosses of rice, similar allelic interactions were found at loci designated as S-7 and S-8, located on chromosomes 7 and 6 respectively. All of them are independent of each other. At the S-5 locus, Indica and Japonica rice have S-5 ⁱ and S-5 ^j alleles respectively and Javanicas, such as Ketan Nangka, have a neutral allele S-5 ⁿ .The S-5 ⁱ /S-5 ^j genotype is semi-sterile due to partial abortion of female gametes carrying S-5 ^j , but both the S-5 ⁿ /S-5 ⁱ and S-5 ⁿ /S-5 ^j genotypes are fertile. The S-5 ⁿ allele is thus a wide-compatibility gene (WCG), and parents homozygous for this allele are called wide-compatible varieties (WCV). Such parents when crossed with Indica or Japonica varieties do not show F₁ hybrid sterility. Wide-compatible parents have been used to overcome sterility barriers in crosses between Indica and Japonica rice. However, a Javanica variety, Ketan Nangka (WCV), showed typical hybrid sterility when crossed to the Indian varieties N22 and Jaya. Further, Dular, another WCV from India, showed typical hybrid sterility when crossed to an IRRI line, IR2061-628-1-6-4-3(IR2061-628). By genetic analyses using isozyme markers, a new locus causing hybrid sterility in crosses between Ketan Nangka and the Indicas was located near isozyme loci Est-1 and Mal-1 on chromosome 4, and was designated as S-9. Another new locus for hybrid sterility in the crosses between Dular and the IR2061-628 was identified and was found linked to four isozyme loci, Sdh-1, Pox-2, Acp-1 and Acp-2, on chromosome 12. It was designated as S-15. On the basis of allelic interactions causing female-gamete abortion, two alleles were found at S-9, S-9 ^kn in Ketan Nangka and S-9 ⁱ in N22 and Jaya. In the heterozygote, S-9 ^kn /S-9 ⁱ , which was semisterile, female gametes carrying S-9 ^kn were aborted. The hybrid of Dular and IR2061-628, with a genetic constitution of S-15 ^Du /S-15 ⁱ , was semi-sterile and the female gametes carrying S-15 ^Du were aborted. A Japonica tester variety, Akihikari, and an Indica variety, IR36, were found to have neutral alleles, S-9 nand S-15 n, at these loci, in addition to S-7 nand at S-7. The accumulation of three neutral alleles into a breeding line should help solve the hybrid sterility problem in wide crosses of rice.     

Natural occurrence of Fusarium mycotoxins in field samples from the 1992 Wisconsin corn crop.

Analysis of 98 moldy corn samples collected in Wisconsin between November 1992 and January 1993 for Fusarium toxins by various immunochemical assays revealed overall average mycotoxin concentrations of 305.6, 237.7, and 904.3 ng/g for type A trichothecenes (TCTCs), deoxynivalenol (DON)-related type B TCTCs (total DON), and zearalenone (ZE), respectively. A small portion (5.1%) of the samples was found to be contaminated with high levels ( > 1 microgram/g) of type A TCTCs and total DON during the whole survey. Over 40% of the samples had 100 to 1,000 ng of total DON per g, while 17% of the samples had the same levels of type A TCTCs. The analytical data were consistent with those from mycological examinations for the samples in which various toxic Fusarium spp., including F. sporotrichioides, F. poae, and F. graminearum, were found. The samples received in November 1992 had relatively low concentrations of toxin; the average levels of type A TCTCs and total DON were 9.9 and 79 ng/g, respectively. The toxin concentrations became progressively higher in the samples received in December. The average levels for the type A TCTCs and total DON increased to 920 and 335 ng/g, respectively. However, the levels of ZE were higher in the samples collected earlier. The average levels for samples collected in November and late December were 1,195 and 242 ng/g, respectively. Analysis of selected samples by high-performance liquid chromatography monitoring with an enzyme-linked immunosorbent assay revealed that T-2 toxin, HT-2 toxin, diacetoxyscirpenol, neosolaniol, and T-2 tetraol (T-2-4ol) were common in these samples. Statistical analysis revealed a weak correlation between the levels of total type A TCTCs and total DON in the samples (r = 0.18, P = 0.09), but a strong correlation between the levels of ZE and total type B TCTCs (r = 0.75, P < 0.0001) was found. The mycotoxin levels of total type A TCTCs, total DON-related type B TCTCs, and ZE in the cobs (5.2, 3.9, and 21 micrograms/g, respectively) were considerably higher than those in the kernels (1.0, 0.5, and 0.5 microgram/g, respectively). The type A toxin levels increased from a range of 14 to 35 ng/g to a range of 110 to 538 ng/g after the moldy corn samples were held at 5 degrees C for 8 days in the laboratory.     

Engineering dynamics of growth factors and other therapeutic ligands

Peptide growth factors and other receptor-binding cytokine ligands are of interest in contemporary molecular health care approaches in applications such as wound healing, tissue regeneration, and gene therapy. Development of effective technologies based on operation of these regulatory molecules requires an ability to deliver the ligands to target cells in a reliable and well-characterizable manner. Quantitative information concerning the fate of peptide ligands within tissues is necessary for adequate interpretation of experimental observations at the tissue level and for truly rational engineering design of ligand-based therapies. To address this need, we are undertaking efforts to elucidate effects of key molecular and cellular parameters on temporal and spatial distribution of cytokines in cell population and cell/matrix systems. In this article we summarize some of our recent findings on dynamics of growth factor depletion by cellular endocytic trafficking, growth factor transport through cellular matrices, and growth factor production and release by autocrine cell systems. (c) 1996 John Wiley & Sons, Inc.     

The Mouse Glutathione PeroxidaseGpx2Gene Maps to Chromosome 12; Its PseudogeneGpx2-psMaps to Chromosome 7

TheGPX2gene codes for GSHPx-GI, a glutathione peroxidase whose mRNA is readily detectable in the gastrointestinal tract. AlthoughGPX2is a single gene in humans, there are two genes in the mouse genome with homology toGPX2.By analyzing a panel of mouse interspecies DNA from the Jackson Laboratory's backcross resource, we have chromosomally mapped these two genes. One was mapped to the central region of mouse chromosome 12 betweenD12Mit4andD12Mit5,nearfosandTgfb3.This region is homologous to human 14q24.1, where humanGPX2has been mapped, and most likely represents the functional mouseGpx2gene. The otherGpx2-like gene was mapped to mouse chromosome 7 betweenPcsk3andHbb.We have isolated the latter gene from a P1 phage library. Its pseudogene nature is revealed by the sequence analysis: (a) it is intronless; (b) it has a single nucleotide deletion in the coding region; and (c) it has a poly(A) tail at its 3′-untranslated region.     

人胎视网膜含NOS神经元的发育

本文用一氧化氮合酶（ＮＯＳ）的组织化学方法对胎龄１５周至３６周的人胎视网膜含ＮＯＳ神经元的发育进行了研究。胚胎１５周视网膜颞侧半少部分神经元即有ＮＯＳ的表达,２０周视网膜含ＮＯＳ神经元数密度达峰值。大部分含ＮＯＳ神经元胞体位于内核层内带,只少部分位于节细胞层,其突起均分布于内同层,形成内同层的１、３、５亚层。含ＮＯＳ神经元的形态各异,依据其突起的多少分Ⅰ、Ⅱ、Ⅲ等三种类型,其中Ⅱ、Ⅲ型含ＮＯＳ神经元在２８周以后才开始出现,且愈近晚期胎龄,它们所占含ＮＯＳ神经元的数量比呈上升趋势。随视网膜发育成熟,含ＮＯＳ神经元胞体均面积呈不断增大的变化。本文结果显示：人胎视网膜内核层含ＮＯＳ神经元为无长突细胞,节细胞层的Ⅰ型含ＮＯＳ神经元为移位无长突细胞,推测它们在视网膜的发育过程中对内网层突触的形成与修饰可能起有重要作用。     

棉铃虫致病菌BT—931菌株的应用研究

１９９２－１９９３年,作者从菏泽、聊城棉田采集的自然罹病死亡棉铃虫幼虫体内,分离到２个较高毒效的Ｂｔ菌株,编号为ＢＴ—９３１和ＢＴ—０２１,经室内毒力测定和田间药效试验表明,防效及保蕾效果接近或超过化学农药,菌药混剂３—５天平均防治效果达８７．０－９１．６％,增效作用显著。经１９９４年大田防治示范表明,利用ＢＴ—９３１菌剂。配合化学农药防治棉铃虫,具有成本低、保护天敌、持效期长、增产效益高等优点。本研究对菌剂的田间应用技术进行了试验示范。     

人粒细胞集落刺激因子（hG－CSF）cDNA3′－UTR对其表达的影响

利用人粒细胞集落刺激因子（ｈＧ－ＣＳＦ）ｃＤＮＡ３′端非翻译区（３′－ＵＴＲ）中存在的ＤｒａⅠ酶切位点,通过部分酶切与完全酶切,删除３′－ＵＴＲ不同长度,构建了四种ｈＧ－ＣＳＦｃＤＮＡ瞬时重组表达质粒。转染ＣＯＳ－７细胞后,生物活性测定结果提示,ｈＧ－ＣＳＦｃＤＮＡ３′－ＵＴＲ对其表达起负调控作用,其关键性序列位于紧接终止密码子ＴＧＡ下游的６５ｂｐ范围内,３′－ＵＴＲ对ｈＧ－ＣＳＦｃＤＮＡ表达的影响与转录水平的差别有一定关系。     

根霉超氧化物歧化酶同工酶类型的鉴别

利用ＫＣＮ、Ｈ_２Ｏ２和ＳＤＳ的选择性反应引起的ＳＯＤ同工酶谱带变化即可鉴别粗抽提液中的ＳＯＤ同工酶类型;用这种方法对五株不同种根霉的鉴别实验表明,它们均不同程度地含有Ｃｕ,Ｚｎ型和Ｍｎ型两种ＳＯＤ,前者约占８０％左右,后者只占２０％左右。用邻苯三酚自氧化法对样品中ＳＯＤ活性测定结果与在同工酶谱上的鉴别结果基本一致。     

Simultaneous occurrence of fumonisin B1 and other mycotoxins in moldy corn collected from the People's Republic of China in regions with high incidences of esophageal cancer.

A total of 31 corn samples collected from households in the counties of Cixian and Linxian of the People's Republic of China, where high incidences of esophageal cancer have been reported, were analyzed for fumonisin B1 (FB1), aflatoxin, and total trichothecene mycotoxins. High levels of FB1 (18 to 155 ppm; mean, 74 ppm) were found in 16 of the samples that showed heavy mold contamination. FB1, at lower levels (20 to 60 ppm; mean, 35.3 ppm), was also found in 15 samples, collected from the same households, that did not show any visible mold contamination. The levels of aflatoxin in the samples were low (1 to 38.4 ppb; mean, 8.61 ppb). High levels of total type-A trichothecenes were also found in the moldy corn samples (139 to 2,030 ppb; mean, 627 ppb). Immunochromatography of selected samples revealed that these samples contained T-2 toxin, HT-2 toxin, iso-neosolaniol, monoacetoxyscirpenol, and several other type-A trichothecenes. The concentration of total type-B trichothecenes in 15 moldy corn samples was in the range of 470 to 5,826 ppb (mean, 2,359 ppb). High levels (3.7 to 5.0 mg/g) of FB1 were produced in corn in the laboratory by five Fusarium moniliforme strains isolated from the moldy corn. These fungi were also capable of forming various nitrosamines (5 to 16 micrograms per flask) in the presence of nitrate and precursor amines.(ABSTRACT TRUNCATED AT 250 WORDS)