水稻雌性不育材料FS－1胚囊败育的细胞学观察

以水稻雌性不育材料FS－1为试验材料,采用石蜡连续切片技术对FS－1及其亲本藤坂5号幼穗发育中期的胚囊进行观察。结果表明：（1）亲本的胚囊都能正常发育分化,成为功能健全的雌配子体,而FS－1的胚囊却普通发生败育,在胚囊原来的区域充满了胚囊残迹和解体的珠心细胞。（2）败育基本上发生在功能大孢子发生期,近合点端的大孢子和珠孔端的三个大孢子都发生解体,实验中未发现二核,四核或八核的败育胚囊,我们初步认为,FS－1胚囊败育发生在功能大孢发生期。     

Taxonomic and ecological profile of `green tide' species of Ulva (Ulvales,Chlorophyta) in central Philippines

Hydrobiologia - Ulva spp. are common in the intertidal zones of the Philippines, but, at certain times, could over-proliferate producing blooms or `green tide' in some protected bays. In Mactan...     

Microdissected region-specific gene expression analysis with methacarn-fixed, paraffin-embedded tissues by real-time RT-PCR.

We have previously shown methacarn to be a versatile fixative for analysis of proteins, DNA, and RNA in paraffin-embedded tissues (PETs). In this study we analyzed its suitability for quantitative mRNA expression analysis of microdissected PET specimens using a real-time RT-PCR technique. Fidelity of expression in the methacarn-fixed PET sections, with reference to dose-dependent induction of cytochrome P450 2B1 in the phenobarbital-treated rat liver, was high in comparison with the unfixed frozen tissue case, even after hematoxylin staining. RNA yield from methacarn-fixed PET sections was equivalent to that in unfixed cryosections and was also not significantly affected by hematoxylin staining. Correlations between the expression levels of target genes and input amounts of extracted RNA in the range of 1-1000 pg were very high (correlation coefficients >0.98), the regression curves being similar to those with unfixed cryosections. Although cell numbers should be optimized for each target gene/tissue, >/=200 cells were necessary for accurate measurement in 10-microm-thick rat liver sections judging from the variation of measured value in small microdissected areas. These results indicate high performance with methacarn, close to that of unfixed tissues, regarding quantitative expression analysis of mRNAs in microdissected PET-specimens.     

Nitric oxide-cGMP pathway is involved in endotoxin-induced contractile dysfunction in rat hearts.

The mechanisms by which endotoxemia causes cardiac depression have not been fully elucidated. The present study examined the involvement of nitric oxide (NO) in this pathology. Rats were infused with lipopolysaccharide (LPS) or saline, and the plasma and myocardial NO(2)(-) and NO(3)(-) (NOx) concentrations were measured before or 3, 6, and 24 h after treatment. The hearts were then immediately isolated and mounted in a Langendorff apparatus, and left ventricular developed pressure (LVDP) was determined before biochemical analysis of the myocardium. LPS injection effected the expression of inducible NO synthase (iNOS) in the myocardium, a marked increase in plasma and myocardial NOx levels, and a significant decline in LVDP compared with saline controls. The LPS-induced NO production and concomitant cardiac depression were most pronounced 6 h after LPS injection and were accompanied by a significant increase in myocardial cGMP content. Myocardial ATP levels were not significantly altered after LPS injection. Significant negative correlation was observed between LVDP and myocardial cGMP content, as well as between LVDP and plasma NOx levels. Aminoguanidine, an inhibitor of iNOS, significantly attenuated the LPS-induced NOx production and contractile dysfunction. Furthermore, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, an inhibitor of soluble guanylate cyclase, significantly decreased myocardial cGMP content and attenuated the contractile depression, although aminoguanidine or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one was not able to completely reverse myocardial dysfunction. Our data suggest that endotoxin-induced contractile dysfunction in rat hearts is associated with NO production by myocardial iNOS and a concomitant increase in myocardial cGMP.     

Detection of Bacteria Carrying the stx2 Gene by In Situ Loop-Mediated Isothermal Amplification

A new in situ DNA amplification technique for microscopic detection of bacteria carrying a specific gene is described. Loop-mediated isothermal amplification (LAMP) was used to detect stxA₂ in Escherichia coli O157:H7 cells. The mild permeabilization conditions and low isothermal temperature used in the in situ LAMP method caused less cell damage than in situ PCR. It allowed use of fluorescent antibody labeling in the bacterial mixture after the DNA amplification for identification of E. coli O157:H7 cells with an stxA₂ gene. Higher-contrast images were obtained with this method than with in situ PCR.     

Gravitropic response plays an important role in the nutational movements of the shoots of Pharbitis nil and Arabidopsis thaliana

The shoots of a Japanese strain of morning glory ( Pharbitis nil  ) called 'Shidare-asagao' display agravitropic and weeping growth. It has been shown that this shoot agravitropism may be due to the defective differentiation of endodermal cells that contain statoliths. Roots of the weeping morning glory show normal responsiveness to gravity and the shoots are positively phototropic. Shoots of the morning glory cultivar Violet used as a wild type exhibited distinct circumnutation with circular movements that increase as the plants grow. In weeping morning glory, however, nutation was limited to slight back and forth or side to side movements. To determine whether endodermal cells participate in circumnutation through a function that is independent of their role in gravitropism, the nutational movements of various gravitropic mutants of Arabidopsis thaliana were compared. The inflorescences of wild-type Arabidopsis showed relatively large circular movements. Inflorescences of the pgm-1 mutant, which is defective in starch synthesis, showed reduced nutation. Even more seriously affected were the sgr1-1 / scr-3 and sgr7-1 / shr-2 mutants, which are defective in endodermal cell differentiation, and the auxin-resistant axr2-1 mutant showed no significant nutational movements at all. 1- N -naphthylphthalamic acid (NPA) could inhibit Violet circumnutation, supporting the notion that auxin participates in circumnutation. Thus, the gravitropic response is an essential component in plant shoot circumnutation. Endodermal cells are involved in such circumnutation possibly because of their role in inducing the gravitropic response.     

Development of seaweed communities on suspended substrata with three slope angles

Observations on the development of seaweed communities on concretepanels suspended at three different slope angles – 0^° (horizontal),45^° (inclined) and 90^° (vertical) – were carried out atUranouchi Inlet, Tosa Bay, southern Japan. Each panel had two opposite20 × 20 cm areas, which were affixed with six pieces of 6 × 9 cmacrylic plate on which algal communities were allowed to colonize. The panelswere suspended 1 m below the sea surface from a floating platform fora period of 6 weeks. The experiments were repeated nine times fromAugust 1996 to October 1997. Young thalli could already be recognized on the panels after 3–4 weeks. Thetype of algal community developing on a panel varied with the slope angleas well as the period of suspension. These were classified into the threedominant green algal genera: Ulva, Enteromorpha and Cladophora. The cover and biomass of particular species were clearlyinfluenced by the slope of the substratum.     

Genetic analysis of cataract in Ihara epileptic rat

We analyzed the mode of inheritance of cataract in the Ihara epileptic rat (IER) by crossing experiments, and mapped cataract-related genes by linkage analysis. Cataract did not develop in the F₁ animals, but it developed in both male and female animals of backcross and F₂. The occurrence rate of cataract was 48.5% in the backcross progeny and 19.4% in the F₂ progeny. Thus, the character was considered to be inherited by the autosomal recessive mode. We found two groups that differed according to the time of onset among the backcross and F₂ progeny: an early-onset group (EOG), in which cataracts developed by about 4 months after birth, and a late-onset group (LOG), in which cataracts developed 8 months or more after birth. Linkage analysis indicated the presence of one cataract gene each on Chromosome (Chr) 8 and Chr 15, and the cataract was demonstrated to be governed by more than one gene. The gene on Chr 8 was named Cati1, and that on Chr 15, Cati2. Cati1 was involved in the occurrence of cataract, and the conditions required for cataract to develop were Cati1 ⁱ/Cati1 ⁱ or Cati1 ⁱ/Cati1 ^w. However, in the cataract rats with Cati1 ⁱ/Cati1 ^w, the allele of Cati2 was always Cati2 ⁱ/Cati2 ⁱ. Cati2 was involved in the timing of onset of the cataract, and the precondition for early onset was Cati2 ⁱ/Cati2 ⁱ. Received: 19 November 1999 / Accepted: 1 November 2000     

Selective localization of G protein γ5 subunit in the subventricular zone of the lateral ventricle and rostral migratory stream of the adult rat brain

G proteins play important roles in transmembrane signal transduction, and various isoforms of each subunit, alpha, beta and gamma, are highly expressed in the brain. The Ggamma5 subunit is a minor isoform in the adult brain, but we have previously shown it to be highly expressed in the proliferative region of the ventricular zone in the rat embryonic brain. We show here that Ggamma5 is also selectively localized in a proliferative region in the adult rat brain, including the subventricular zone of the lateral ventricle and rostral migratory stream. The Galphai2 subunit colocalized with Ggamma5 in these regions, the two subunits being present in neuronal precursors and ependymal cells but not in proliferating astrocytes. In addition, intense staining of Ggamma5 was seen in axons of the olfactory neurons, which are known to regenerate. These results suggest specific roles for Ggamma5 in precursor cells during neurogenesis so that this isoform might be a useful biological marker.     

Functional Role for Protein Kinase Cβ as a Regulator of Stress-Activated Protein Kinase Activation and Monocytic Differentiation of Myeloid Leukemia Cells

Human myeloid leukemia cells respond to 12-O-tetradecanoylphorbol-13-acetate (TPA) and other activators of protein kinase C (PKC) with induction of monocytic differentiation. The present studies demonstrated that treatment of U-937 and HL-60 myeloid leukemia cells with TPA, phorbol-12,13-dibutyrate, or bryostatin 1 was associated with the induction of stress-activated protein kinase (SAPK). In contrast, TPA-resistant TUR and HL-525 cell variants deficient in PKCβ failed to respond to activators of PKC with the induction of SAPK. A direct role for PKCβ in TPA-induced SAPK activity in TUR and HL-525 cells that stably express PKCβ was confirmed. We showed that TPA induced the association of PKCβ with MEK kinase 1 (MEKK-1), an upstream effector of the SAPK/ERK kinase 1 (SEK1)→SAPK cascade. The results also demonstrated that PKCβ phosphorylated and activated MEKK-1 in vitro. The functional role of MEKK-1 in TPA-induced SAPK activity was further supported by the demonstration that the expression of a dominant negative MEKK-1 mutant abrogated this response. These findings indicate that PKCβ activation is necessary for activation of the MEKK-1→SEK1→SAPK cascade in the TPA response of myeloid leukemia cells.