The LcKNAT1-LcEIL2/3 Regulatory Module Is Involved in Fruitlet Abscission in Litchi

Large and premature organ abscission may limit the industrial development of fruit crops by causing serious economic losses. It is well accepted that ethylene (ET) is a strong inducer of organ abscission in plants. However, the mechanisms underlying the control of organ abscission by ET are largely unknown. We previously revealed that LcKNAT1, a KNOTTED-LIKE FROM ARABIDOPSIS THALIANA1 (KNAT1)-like protein, acted as a negative regulator in control of fruitlet abscission through suppressing the expression of ET biosynthetic genes in litchi. In this study, we further reported that LcKNAT1 could also directly repress the transcription of LcEIL2 and LcEIL3, two ETHYLENE INSENSITIVE 3-like (EIL) homologs in litchi, which functioned as positive regulators in ET-activated fruitlet abscission by directly promoting the expression of genes responsible for ET biosynthesis and cell wall degradation. The expression level of LcKNAT1 was downregulated, while LcEIL2/3 was upregulated at the abscission zone (AZ) accompanying the fruitlet abscission in litchi. The results of electrophoretic mobility shift assays (EMSAs) and transient expression showed that LcKNAT1 could directly bind to the promoters of LcEIL2 and LcEIL3 and repress their expression. Furthermore, the genetic cross demonstrated that the β-glucuronidase (GUS) expression driven by the promoters of LcEIL2 or LcEIL3 at the floral AZ was obviously suppressed by LcKNAT1 under stable transformation in Arabidopsis. Taken together, our findings suggest that the LcKNAT1-LcEIL2/3 regulatory module is likely involved in the fruitlet abscission in litchi, and we propose that LcKNAT1 could suppress both ET biosynthesis and signaling to regulate litchi fruit abscission.

KNOX protein KNAT1 regulates fruitlet abscission in litchi by repressing ethylene biosynthetic genes

Abscission is triggered by multiple environmental and developmental cues, including endogenous plant hormones. KNOTTED-LIKE HOMEOBOX (KNOX) transcription factors (TFs) play an important role in controlling abscission in plants. However, the underlying molecular mechanism of KNOX TFs in abscission is largely unknown. Here, we identified LcKNAT1, a KNOTTED-LIKE FROM ARABIDOPSIS THALIANA1 (KNAT1)-like protein from litchi, which regulates abscission by modulating ethylene biosynthesis. LcKNAT1 is expressed in the fruit abscission zone and its expression decreases during fruitlet abscission. Furthermore, the expression of the ethylene biosynthetic genes LcACS1, LcACS7, and LcACO2 increases in the fruit abscission zone, in parallel with the emission of ethylene in fruitlets. In vitro and in vivo assays revealed that LcKNAT1 inhibits the expression of LcACS/ACO genes by directly binding to their promoters. Moreover, ectopic expression of LcKNAT1 represses flower abscission in tomatoes. Transgenic plants expressing LcKNAT1 also showed consistently decreased expression of ACS/ACO genes. Collectively, these results indicate that LcKNAT1 represses abscission via the negative regulation of ethylene biosynthesis.

The HD-Zip transcription factor LcHB2 regulates litchi fruit abscission through the activation of two cellulase genes

Cellulases play important roles in the shedding of plant organs; however, little is yet known about the functions of cellulase genes during the process of organ abscission. Abnormal fruitlet abscission is a serious problem in the production of litchi (Litchi chinensis), an economically important fruit widely grown in South Asia. In this study, two abscission-accelerating treatments (carbohydrate stress and application of ethephon) were evaluated in litchi fruitlets. Cell wall degradation and cell separation were clearly observed in the abscission zones of treated fruitlets, consistent with enhanced cellulase activities and reduced cellulose contents. The expression of two cellulase genes (LcCEL2 and LcCEL8) was strongly associated with abscission. Floral organs of transgenic Arabidopsis overexpressing LcCEL2 or LcCEL8 showed remarkably precocious abscission. Electrophoretic mobility shift assays and transient expression experiments demonstrated that a novel homeodomain-leucine zipper transcription factor, LcHB2, could directly bind to and activate HD-binding cis-elements in the LcCEL2 and LcCEL8 promoters. Our results provide new information regarding the transcriptional regulation of the cellulase genes responsible for cell wall degradation and cell separation during plant organ shedding, and raise the possibility of future manipulation of litchi fruitlet abscission by modulation of the activities of these two cellulases.

Genome-Wide Identification of Histone Modifiers and Their Expression Patterns during Fruit Abscission in Litchi

Modifications to histones, including acetylation and methylation processes, play crucial roles in the regulation of gene expression in plant development as well as in stress responses. However, limited information on the enzymes catalyzing histone acetylation and methylation in non-model plants is currently available. In this study, several histone modifier (HM) types, including six histone acetyltransferases (HATs), 11 histone deacetylases (HDACs), 48 histone methyltransferases (HMTs), and 22 histone demethylases (HDMs), are identified in litchi (Litchi chinensis Sonn. cv. Feizixiao) based on similarities in their sequences to homologs in Arabidopsis (A. thaliana), tomato (Solanum lycopersicum), and rice (Oryza sativa). Phylogenetic analyses reveal that HM enzymes can be grouped into four HAT, two HDAC, two HMT, and two HDM subfamilies, respectively, while further expression profile analyses demonstrate that 17 HMs were significantly altered during fruit abscission in two field treatments. Analyses reveal that these genes exhibit four distinct patterns of expression in response to fruit abscission, while an in vitro assay was used to confirm the HDAC activity of LcHDA2, LcHDA6, and LcSRT2. Our findings are the first in-depth analysis of HMs in the litchi genome, and imply that some are likely to play important roles in fruit abscission in this commercially important plant.

Identification and molecular characterization of an IDA-like gene from litchi, LcIDL1, whose ectopic expression promotes floral organ abscission in Arabidopsis

Unexpected abscission of flowers or fruits is a major limiting factor for crop productivity. Key genes controlling abscission in plants, especially in popular fruit trees, are largely unknown. Here we identified a litchi (Litchi chinensis Sonn.) IDA-like (INFLORESCENCE DEFICIENT IN ABSCISSION-like) gene LcIDL1 as a potential key regulator of abscission. LcIDL1 encodes a peptide that shows the closest homology to Arabidopsis IDA, and is localized in cell membrane and cytoplasm. Real-time PCR analysis showed that the expression level of LcIDL1 accumulated gradually following flower abscission, and it was obviously induced by fruit abscission-promoting treatments. Transgenic plants expressing LcIDL1 in Arabidopsis revealed a role of LcIDL1 similar to IDA in promoting floral organ abscission. Moreover, ectopic expression of LcIDL1 in Arabidopsis activated the expression of abscission-related genes. Taken together, our findings provide evidence that LcIDL1 may act as a key regulator in control of abscission.

Genome-wide digital transcript analysis of putative fruitlet abscission related genes regulated by ethephon in litchi

The high level of physiological fruitlet abscission in litchi (Litchi chinensis Sonn.) causes severe yield loss. Cell separation occurs at the fruit abscission zone (FAZ) and can be triggered by ethylene. However, a deep knowledge of the molecular events occurring in the FAZ is still unknown. Here, genome-wide digital transcript abundance (DTA) analysis of putative fruit abscission related genes regulated by ethephon in litchi were studied. More than 81 million high quality reads from seven ethephon treated and untreated control libraries were obtained by high-throughput sequencing. Through DTA profile analysis in combination with Gene Ontology and KEGG pathway enrichment analyses, a total of 2730 statistically significant candidate genes were involved in the ethephon-promoted litchi fruitlet abscission. Of these, there were 1867 early-responsive genes whose expressions were up- or down-regulated from 0 to 1 d after treatment. The most affected genes included those related to ethylene biosynthesis and signaling, auxin transport and signaling, transcription factors (TFs), protein ubiquitination, ROS response, calcium signal transduction, and cell wall modification. These genes could be clustered into four groups and 13 subgroups according to their similar expression patterns. qRT-PCR displayed the expression pattern of 41 selected candidate genes, which proved the accuracy of our DTA data. Ethephon treatment significantly increased fruit abscission and ethylene production of fruitlet. The possible molecular events to control the ethephon-promoted litchi fruitlet abscission were prompted out. The increased ethylene evolution in fruitlet would suppress the synthesis and polar transport of auxin and trigger abscission signaling. To the best of our knowledge, it is the first time to monitor the gene expression profile occurring in the FAZ-enriched pedicel during litchi fruit abscission induced by ethephon on the genome-wide level. This study will contribute to a better understanding for the molecular regulatory mechanism of fruit abscission in litchi.

[Study on the adsorption of collagen onto surfaces with imaging ellipsometry]

The adsorption of collagen onto hydrophilic and hydrophobic surfaces was studied with imaging ellipsometry in different pH, adsorption time, ion strength and BSA existence. The results showed that there was more collagen adsorbed onto hydrophobic surfaces than onto hydrophilic surfaces. The maximum collagen adsorption was observed at pH 7.2. The existence of BSA affected the adsorption of collagen onto hydrophobic surfaces more than that onto hydrophilic surfaces.

[Transportation and transformation of 14C-phenanthrene in closed chamber (nutrient solution-lava-plant-air) system]

The transportation and transformation of 14C-phenanthrene in a closed 'plant-lava-nutrient solution-air' chamber system was studied by using radioactivity technology. The results showed that in this closed chamber system, phenanthrene was degraded fast. The radioactivity of 14C left at 23d in the nutrient solution was only 25% of applied. At the end of experiment (46d), the distribution sequence of 14C activity in the components of closed chamber system was root (38.55%) > volatile organic compounds (VOCs, 17.68%) > lava (14.35%) > CO2 (11.42%) > stem (2%). 14C-activities in plant tissue were combined with the tissue, and existed in the forms of lava-bound(root 4.68%; stem and leaves 0.68%) and polar metabolites (root 23.14%; stem 0.78%).

[Soil macropore and its studying methodology]

This paper discusses the definition, size, types, formation of soil macropores. Soil macropore (> 0.03 mm) is the pore space that provides preferential paths of flow. The shape of macropore varies from crack or fissure, through to cylindrical pipe. Macropore is formed in main ways: by plant roots and soil fauna; wet-dry and freeze-thaw cycles; chemical weathering. The studying method of macropore divided into direct measurement and indirect description, which suitability and limitation are also reviewed.

[Using self-assembled monolayers to understand the interactions of surfaces with cells]

It is important to understand the interactions of surfaces with cells. Self-assembled monolayers formed on the adsorption of long-chain alkanethiols to the surface of gold or alkylsilanes to hydroxylated surfaces and their patterned surfaces permit of understanding and controlling over the surface-cell interactions at the molecular scale. The present paper reviewed the latest research in using patterned self-assembled monolayers to understand surface-cell interactions.

Effect of long-term exposure to fluoride in drinking water on risks of bone fractures

Findings on the risk of bone fractures associated with long-term fluoride exposure from drinking water have been contradictory. The purpose of this study was to determine the prevalence of bone fracture, including hip fracture, in six Chinese populations with water fluoride concentrations ranging from 0.25 to 7.97 parts per million (ppm). A total of 8266 male and female subjects > or =50 years of age were enrolled. Parameters evaluated included fluoride exposure, prevalence of bone fractures, demographics, medical history, physical activity, cigarette smoking, and alcohol consumption. The results confirmed that drinking water was the only major source of fluoride exposure in the study populations. A U-shaped pattern was detected for the relationship between the prevalence of bone fracture and water fluoride level. The prevalence of overall bone fracture was lowest in the population of 1.00-1.06 ppm fluoride in drinking water, which was significantly lower (p < 0.05) than that of the groups exposed to water fluoride levels > or =4.32 and < or =0.34 ppm. The prevalence of hip fractures was highest in the group with the highest water fluoride (4.32-7.97 ppm). The value is significantly higher than the population with 1.00-1.06 ppm water fluoride, which had the lowest prevalence rate. It is concluded that long-term fluoride exposure from drinking water containing > or =4.32 ppm increases the risk of overall fractures as well as hip fractures. Water fluoride levels at 1.00-1.06 ppm decrease the risk of overall fractures relative to negligible fluoride in water; however, there does not appear to be similar protective benefits for the risk of hip fractures.

[Preferential flow and its effect on solute migration in soil]

The characteristics of soil preferential flow and the preferential migrate in soil for non-absorptive bromide and nitrate ions were studied. With undisturbed and packed soil columns, the results showed that soil preferential flow was characterized with preferential breakthrough, non-symmetric breakthrough curve, lateral infiltration, tailing and so on. The preferential breakthrough for Br- was 24 hours after it was applied, and the leachate volume was only 0.04 times as-much as the pore volumes. The preferential flow for Br- accounted for 26% of total flux in the undisturbed soil columns. But the accumulative leachate mass for Br- resulted from the preferential flow were 86.7% of total accumulative leachate mass, showing that the soil preferential flow accounted for relative small ratio of the flux, but caused relative much more solute transference. NO3- was moved down rapidly by preferential flow at only one time as large as pore volumes, and got 11% of the applied amount, respectively. As a result of the preferential flow, the lateral infiltration flow enabled Br- and NO3- rapidly distribute and diffuse into the deeper soil.

Trace element levels in drinking water and cognitive function among elderly Chinese

The relation between trace element levels in drinking water and cognitive function was investigated in a population-based study of elderly residents (n = 1,016) in rural China in 1996-1997. Cognitive function was measured using a Chinese translation of the Community Screening Interview for Dementia. A mixed effects model was used to evaluate the effect of each of the elements on cognitive function while adjusting for age, sex, and educational level. Several of the elements examined had a significant effect on cognitive function when they were assessed in a univariate context. However, after adjustment for other elements, many of these results were not significant. There was a significant quadratic effect for calcium and a significant zinc-cadmium interaction. Cognitive function increased with calcium level up to a certain point and then decreased as calcium continued to increase. Zinc showed a positive relation with cognitive function at low cadmium levels but a negative relation at high levels.

The malaria circumsporozoite protein: interaction of the conserved regions I and II-plus with heparin-like oligosaccharides in heparan sulfate

The malaria circumsporozoite (CS) protein binds to glycosaminoglycans from heparan sulfate proteoglycans on the cell surface of hepatocytes and is specifically cleared from the bloodstream by the liver. We show here that the two conserved regions, I and II-plus, of the CS protein, in a concerted action, preferentially bind to highly sulfated heparin-like oligosaccharides in heparan sulfate. In a concentration-dependent manner, peptides representing region I and region II-plus inhibited the binding of recombinant CS protein to HepG2 cells by 62 and 84%, respectively. Furthermore, the action of endoproteinase Arg-C, which cleaves the recombinant CS constructs CS27IVC and CSFZ(Cys) predominantly at the conserved region I, was inhibited by heparin in a concentration-dependent fashion. CSFZ(Cys), which has a higher affinity to HSPGs than CS27IVC, was stabilized by heparin at a w/w ratio (CS protein:glycosaminoglycan) of 20/1, whereas full protection of CS27IVC required more heparin (5/1). Heparan sulfate provided full protection of CSFZ(Cys) only at a ratio of 1/10. Native fucoidan as well as normally sulfated fuco-oligosaccharides (0.76 mol sulfate/mol fucose) inhibited Plasmodium berghei development in HepG2 cells by 84 and 66%, respectively, in a concentration-dependent manner and sporozoite invasion into CHO cells by 80%. Desulfated fucoidan oligosaccharides were inactive. These results may explain the selective interaction between the CS protein and the unique heparan sulfate from liver, which is noted for its unusually high degree of sulfation, and may provide a plausible explanation for the selective targeting of the malaria CS protein to the liver.

Regulation of alpha- and beta-hemolysins by the sar locus of Staphylococcus aureus

We recently identified a locus on the Staphylococcus aureus chromosome, designated sar, for staphylococcal accessory regulator, that is involved in the global regulation of extracellular and cell wall-associated proteins. Previous phenotypic and Southern blot analyses with Tn917 and agr probes indicated that this locus is distinct from agr, a previously described global regulator of exoproteins in S. aureus. To understand the mode of regulatory control of exoprotein synthesis by the sar locus, the sar genotype was transduced from the original sar mutant 11D2 into two prototypic S. aureus strains, RN6390 and RN450, with well-defined genetic backgrounds. An analysis of extracellular protein profiles by use of silver-stained sodium dodecyl sulfate gels revealed alterations in the pattern of exoprotein production in the late log-early stationary phase in the sar mutants in comparison with the corresponding parents. In addition, most of the phenotypic changes that occurred in the conversion from the sar+ genotype to the sar genotype in mutant 11D2 were also found in these mutants. Northern (RNA) blot analyses of two exoprotein transcripts (alpha- and beta-hemolysins) from strain RN6390 and its corresponding sar mutant revealed downregulation of these transcripts in the mutant. Serial studies of these hemolysin transcripts at various growth intervals demonstrated that the transcriptional regulation of the hemolysin genes by the sar locus began during the log phase and continued into the postexponential phase. These data suggested that the sar locus probably regulates exoprotein genes at the transcriptional level. This mode of regulation is similar to that of exoprotein target gene transcription by agr.

[The appliance of image analysis in the diagnosis of oral Lichen Planus and it's malignant change]

After the Feulgen dying,if the normal oral mucous,oral Lichen planus as well as the pathological cut sheets with atypical dysplasia and malignant change in defferent degrees,use the image analysis technique to measure the morphologic parameters of the nucleus(including nuclear surface area,perimeter maximum nuclear diameter,minimum nulear diameter,equivalent circle diameter,morphological factor) and the amount of DNA,5CER acts as an indes of distinguishing malignancy or benignancy,the value of 5CER in malignant is more than 10% and in benignant is less than 10%.The result of the analysis from the optical microscope differs from the optical microscope differs form the image analysis.There are so many personal factors in the qualitative analysis by optical microscope that it because quite imperative to research for a new diagnosing way.The synchronization of quantitative analysis and qualitative analysis can correct the personal errors in qualitative analysis.It will be very useful for directing the clinical practice and the judgment of prognosis.

[Clinical evaluation of manual and ultrasonic subgingival scaling using image analysis]

The objective of this study was to compare the effect of hand and ultrasonic instrumentation in removing subgingival plaque and calculus.In experiment one,forty-eight teeth from patients were randomly assigned to be scaled with curettes or ultrasonic scaler.Probing depth,clinical attachment level and bleeding index were reexamined 2 months latter.The results demonstrated that no significant differences between the two mehtods.In experiment two,seventeen teeth from six patient were also randomly scaled manualty ultrasonic or uninstrumented as a control.All these teeth were extracted immediately after subgingival scaling.The proportion of tooth surfaces covered by residual plaque and calculus(relative to the total surface area of the side of the tooth)was analysed on each tooth using computerized graphic processing.The findings showed the proportional areas of residual plaque and calculus in teeth.But the hand scaled root surface were much smoother than those treated with ultrasonic scaler.

A method to detect proteinase activity using unprocessed X-ray films

Routine assays to detect proteinases in biological samples are generally tedious and time-consuming. To expedite the recognition of proteinases, we have developed an assay utilizing the gelatin on the surface of an unprocessed Kodak X-Omat AR film as the proteolytic substrate. A positive reaction is indicated by a clear zone on the film after it has been rinsed with running water. This proteinase assay has been found to be inexpensive, rapid, and simple. Besides its ease of use, this assay has been found to be quantitatively reproducible with a well-defined endpoint. More importantly, this assay method is applicable to a variety of proteolytic enzymes under diverse pH (5-8.5) and salt conditions (up to 5 M NaCl) and has a sensitivity similar to that of azocoll. Since the assay does not require sophisticated equipment, it is useful as a general laboratory procedure.