Path Coefficient Analysis, Character Association and Variability Studies in Selected Maize (Zea mays L.) Genotypes Grown in Southern Nigeria

The success of any selection process is greatly enhanced by using appropriate selection indices. The knowledge of the relationship among various traits affecting grain yield is imperative to arrive at potentially effective selection index. The study was carried out to unveil the different attributes of genetic variability, the type of interrelationships among the various traits affecting yield. Fifteen local and improved maize inbred lines were crossed to three tester varieties to develop 45 test cross progenies. The parents and crosses (63 entries in all) were evaluated in two different locations with three replications at each location using the Randomized complete block design (RCBD). Data generated was recorded for the quantitative traits evaluated and subjected to statistical analysis for estimation of various variability parameters namely GCV, PCV, heritability and genetic advance alongside computing genotypic correlation coefficients and path coefficient analysis to unveil the direct and indirect effects of the various traits studied. The analysis of variability parameters evaluated revealed the presence of significant variability for all the traits studied. Grain yield, ear length, ear height, 100-seed weight and ear diameter showed high GCV estimates, with high heritability. The genetic advance was higher for plant height, ear length, grain/row and grain yield. The genotypic correlation coefficient revealed that ear diameter, 100 seed weight, ear length, kernel rows/ear and grains/row had highest significant correlation with grain yield. The path coefficient analysis revealed that highest direct effect on grain yield was exhibited by 100 seed weight followed by grains/row, kernel rows/ear, ear length and ear diameter. Most of the traits exerted their positive indirect effects through 100 – seed weight, kernel rows/ear and grains/row. The inferences of the results of the present study and their possible implications in maize breeding have been revealed.

Estimate of Genetic Variability and Heritability in Some Exotic Germplasm Lines in Kharif Rice (Oryza Sativa L.).

The high genotypic coefficient of variation, high heritability with high genetic advance as percent of mean was observed for grain yield per plant, total tillers per plant, productive tillers per plant and grains per panicle, whereas days to initiation of flowering, days to 50 % flowering and days to maturity had high heritability with low genetic adavance as per cent of mean.

Estimates of Variability, Heritability and Genetic Advance in Certain Inbreeds of Maize (Zea mays, L.).

Genetic variability, heritability (broad sense) and genetic advance were studied in 39 inbreeds of maize. The data were recorded on twelve quantitative traits viz., days to 50% silking, days to 50% tasseling, plant height (cm), ear height (cm), ear length (cm), ear diameter (cm), ear weight without husk (g). ear weight with husk (g), number of kernel rows per ear, number of kernels pr row, 100-seed weight and grain yield per palnt (g). Significant differences among the genotypes were observed for all the characters under study. The phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were highest for characters namely, ear weight without husk, ear weight with husk, number of kernels per row, 100 grain weight and grain yield per plant suggesting that these characters are under the influence of genetic control. High values of heritability coupled with high genetic advance as per cent of mean was noticed for traits viz., grain yield per plant, ear height, plant height, number of kernels per row, number of kernel rows per ear, ear length, 100 grain weight, ear weight with husk and without husk indicating their effectiveness in selection.

Vesicular Stomatitis Virus G Glycoprotein and ATRA Enhanced Bystander Killing of Chemoresistant Leukemic Cells by Herpes Simplex Virus Thymidine Kinase/Ganciclovir

Refractoriness of acute myeloid leukemia (AML) cells to chemotherapeutics represents a major clinical barrier. Suicide gene therapy for cancer has been attractive but with limited clinical efficacy. In this study, we investigated the potential application of herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) based system to inhibit chemoresistant AML cells. We first generated Ara-C resistant K562 cells and doxorubicin-resistant THP-1 cells. We found that the HSV-TK/GCV anticancer system suppressed drug resistant leukemic cells in culture. Chemoresistant AML cell lines displayed similar sensitivity to HSV-TK/GCV. Moreover, HSV-TK/GCV killing of leukemic cells was augmented to a mild but significant extent by all-trans retinoic acid (ATRA) with concomitant upregulation of Connexin 43, a major component of gap junctions. Interestingly, HSV-TK/GCV killing was enhanced by expression of vesicular stomatitis virus G glycoprotein (VSV-G), a fusogenic membrane protein, which also increased leukemic cell fusion. Co-culture resistant cells expressing HSV-TK and cells stably transduced with VSV-G showed that expression of VSV-G could promote the bystander killing effect of HSV-TK/GCV. Furthermore, combination of HSV-TK/GCV with VSV-G plus ATRA produced more pronounced antileukemia effect. These results suggest that the HSV-TK/GCV system in combination with fusogenic membrane proteins and/or ATRA could provide a strategy to mitigate the chemoresistance of AML.

Studies on Genetic Variability, Heritability and Genetic Advance Estimates in Newly Developed Maize Genotypes (Zea Mays L.).

The present study was carried out at Research farm, College of Agriculture, ANGRAU, Rajendranagar, Hyderabad during kharif, 2011 to determine the various parameters of genetic variability, broad sense heritability and genetic advance estimates in newly developed 65 maize genotypes. Analysis of variance revealed that the mean sum of squares due to genotypes showed significant differences for all the 11 characters studied. High to moderate estimates of GCV and PCV were recorded for Grain yield, number of kernels per row, 100-kernel weight, ear length and plant height which represents considerable variability and offers scope for genetic improvement through selection. Grain yield, number of kernels per row, 100-kernel weight, ear length and ear height had high GCV estimates with high heritability. Moderate estimates of genetic advance with high heritability was recorded for Grain yield, number of kernels per row, 100-kernel weight, ear length, ear height and plant height which further leads to improvement of traits under selection. Thus provides better opportunities for selecting plant material for these traits in maize breeding program.

Study on Genetic Parameters on F2 Generation Involving Aromatic Rice Genotypes (O.Sativa).

A field experiment was conducted during kharif, 2010 and rabi 2010-11 at Rice section, ARI, Rajendranagar, involving 7 parents, 7 F1 hybrids and their corresponding F2 populations to study the genetic parameters i.e. variability, heritabiity and genetic advance cross-wise in aromatic rice. A critical examination of genetic parameters in each cross in F2 generation revealed the presence of wider range of variability for both yield and quality traits. The estimates of heritability and genetic advance varied depending on the cross and also the character. Estimates of heritability in broad sense and genetic advance were high for number of grains per panicle, grain yield per plant and kernel length whereas, the estimates were relatively low-moderate for the remaining characters. Keeping in view the gene action known from the genetic parameters, selection on important yield components viz., number of grains per panicle and grain yield per plant and the quality trait, kernel length was suggested to bring out further improvement in aromatic rice. The crosses, RNR 2354 × Sye 632002 and YAMINI × BM 71 for number of grains per panicle, PUSA 1121 X MTU 1010 for grain yield per plant, PUSA 1121 × BM 71 and PUSA 1121× MTU 1010 for kernel length were identified as better crosses for further advancement to develop pure lines with high yield and quality.

Construction and identification of prostate-specific double gene expression vector pIRES-PSMAe/p-TKCx43 / 中华泌尿外科杂志

Objective To construct the prostate-specific double gene expression vector pIRESPSMAe/p-TK-Cx43 and establish the foundation for experimental prostate cancer gene therapy research. Methods Cx43 gene was amplified and cloned into pMD19-T Simple vector. HSV-TK gene was then synthesized and cloned into multiple clone site (MCS) A of the eukaryotie vector plRES. The new plasmid was named plRES-TK: PSMAe/p was obtained and cloned into plRES-TK by replacing CMV promoter. The new plasmid was named plRES-PSMAe/p-TK; Fourth, Cx43 gene was cloned into the MCS B of pIRES-PSMAe/p-TK and the new plasmid was named pIRES-PSMAe/p-TK-Cx43.This plasmid was identified by double digestion with Sal Ⅰ/Not Ⅰ and sequenced; Finally, LNCaP cells were transfected by the plasmid plRES-PSMAe/p-TK-Cx43 and the mRNAs expression of HSV-TK gene and Cx43 gene was tested by RT-PCR. Results The plasmids synthesized in this experiment were double digested respectively and the specific bands of the inserted genes were confirmed by RTPCR. plRES-PSMAe/p-TK-Cx43 was in line with the expected design by DNA sequencing. The mRNAs of TK gene and Cx43 gene were expressed and successfully confirmed by RT-PCR after LNCaP cells transfected with pIRES-PSMAe/p-TK-Cx43. Conclusion Double gene expression vector pIRES-PSMAe/p-TK-Cx43 containing HSV-TK gene and Cx43 gene is constructed successfully.

Novel Gap Junction Molecules, Connexin 37, Enhances the Bystander Effect in HSVtk/GCV Gene Therapy

PURPOSE: Gap junction intercellular communication(GJIC) is an important mechanism of the bystander effect in herpes simplex thymidine kinase/ganciclovir(HSVtk/GCV) gene therapy Therefore, we attempted to enhance the bystander effect in vitro by exogenous overexpressing connexin 37(Cx37) in cells to increase GJIC. METHODS: NIH3T3 cells were transfected with the Cx37 and HSVtk gene or the HSVtk gene alone by the calcium phosphate method, and we detected their expression from these cells by RT-PCR. GCV-mediated cytotoxicity and the bystander effect of each transfectant was then assessed and compared. RESULTS: Cells transfected with HSVtk became sensitive to low concentration of GCV. We found significantly increased cytotoxicity in HSVtk/GCV gene therapy after introduction of the HSVtk and Cx37 genes together compared with the cytotoxicity seen after introduction of the HSVtk gene in vitro. Co-expression of the HSVtk and Cx37 genes potentiates HSVtk/GCV gene therapy through the bystander effect. CONCLUSION: These results indicated that the increase of GJIC using Cx37 have potentiated the by stander effect of HSVtk/GCV therapy, and may be a new approach to improve response in suicidal cancer gene therapy.

Herpes Simplex virus thymidine kinase gene therapy delivered by retroviral or adenoviral vector in mouse model of lewis lung carcinoma / 결핵

BACKGROUND: The antitumor effects of herpes simplex virus thymidine kinase(HSV-tk) and ganciclovir(GCV) strategies for cancer gene therapy have a the following advantages:1) a direct cytotoxicity to HSV-tk modified cancer cells by GCV 2) a cell death by the local transfer of toxic metabolites from the HSV-tk modified cells to nearby unmodified tumor cells(bystander effect), and 3) in vivo bystander effect such as antitumor-immunity. Retroviral and adenoviral sequences can silence transgene expression in cells and mice. In this study, we investigated the above described advantages of HXV-tk/GCV strategy in Lewis lung cell and mouse lung cancer model using retroviral vector and adenoviral vector. Also, we observed whether the expression of a silenced gene can be reactivated by treating cell with butyrate. METHODS: Retrovirus-HSV-tk and adenovirus-HSV-tk vectors were used for the transduction of Lewis lung carcinoma(LLC) cells. The change of HSV-tk expression by butyrate was measured by Western blot.The antitumor activities containing bystander effect were observed in vivo(by MTT assay) and in vivo tumor models of various combinations of LLC and LLC-tk. RESULTS: 1. Butyrate induced the enhancement of HSV-tk expression from adenovirally transduced cells but not from retrovirally transduced cells. 2. Both retrovirus-HSV-tk and adenovirus-HSV-tk vectors with GCV treatment were effective for killing of tumor cell in vitro and suppression of LLC tumorigenicity. Bystander effect was responsible for killing of mixture of LLC-tk and LLC in vitro and in vivo-tumorigenicity model. CONCLUSION: Butyrate could augment adenoviral vector seems to be an effective approach for lung cancer therapy.

Adenovirus-Mediated Vascular Targeting Suicide Gene Therapy in vitro / 中国肿瘤生物治疗杂志

To investigate the potential use of suicide gene systems in vascular targeting gene therapy, HSV-tk/GCV and EC-cd/5-FC systems were established on vascular endothelial cells in vitro by adenovirus transduction. Both modified cell lines were highly sensitive to prodrugs, the IC_(50) for GCV was 0.2?mol/L in IGll/Ad-tk cells, and IC_(50) for 5-FC was 20?mol/L in IGll/Ad-cd cells, while the parental endothelial cells were insensitive even at the highest concentrations of prodrugs in the experiment. Mixed cellular assay showed that significant bystander killing effect was exhibited in modified endothelial cells. Also, the apoptosis involved in these prodrug-mediated growth inhibitions has been shown under electron microscopy. These results indicated that both HSV-tk/GCV and EC-cd/5-FC systems could efficiently suppress vascular endothelial cell growth in vitro , suggesting the feasibility of using suicide gene in vascular targeting gene therapy.

Recombinant Interferon ?2a Synergistically Enhances SKOV3 Ovarian Tumor Cell Killing by the HSV-tk/GCV System / 中国肿瘤生物治疗杂志

Objective: To determine if IFN-?2a and HSV-tk/GCV have synergy on the cell killing of the SKOV3 human ovarian tumor cell line. Methods: hytk gene retroviral vector plasmid was transduced into SKOV3 cells. Both the cytotoxicity and the bystander effect were evaluated after the treatment of GCV. IFN-?2a and HSV-tk/GCV were used together to determine if they have synergy on the tumor cell killing effect, then post-treatment cell cycle analysis was carried out.Results: A dose dependent cell killing of SKOV3/hytk was observed after treatment with GCV. Bystander effect was seen in mixed culture of hytk-positive and -negative cells. Furthermore, IFN-?2a had a significant (P

The relationship of gap junction with the bystander effect in the HSV-TK/GCV treatment / 中国药理学通报

The bystander effect(BE) plays an important role in the gene therapy of cancer by the herpes thymidine kinase/ganciclovir(HSV-TK/GCV) system.It enhances the therapeutic efficacy of this system.Up to now,the exact underlying mechanism of the bystander effect remains unclear.A large body of evidence has indicated a close correlation of the connexin expression and gap junction in the targeted cells to the bystander effect.Here the publications concerning the relationship of gap junction with the bystander effect in the HSV-TK/GCV treatment have been reviewed.The possible cell death signals that can be transferred through gap junction to induce the bystander effect are also discussed.

Suicide gene therapy for mouse bladder cancer using HSV-tk/GCV system / 重庆医科大学学报

Objective:To establish a suicide gene therapy system HSV-tk/GCV for bladder cancer,a treatment in vitro as well as in vivo and to test its efficacy.Methods:Mouse bladder cancer cell line (T739) was transfected with retroviral vector HSV-tk gene.The sensitivity of T739-TK cells to GCV was detected in vitro.In the mouse model of bladder tumor,T739 or T739-TK was implanted beneath the peritoneum of syngeneic mice.When tumors grew to the size of 0.5～0.8cm,intraperitoneal administration of GCV was carried out for 6 days.Changes of tumor size and survival rate of mice were observed.Results:RT-PCR showed that TK gene was transferred into the T739 cell and expressed successfully. In vitro,T739-TK cells became sensitive to low concentrations of GCV.In vivo studies showed similar result.Significant tumor inhibition was found in the T739-TK group after administration of GCV,and the survival time of mice was prolonged.Conclusion:Tumor cells expressing HSV-tk gene were eradicated by administration of GCV in vitro as well as in vivo.

Effect of retroviral HSVtk gene transfer on mice bladder tumor growth in vivo / 重庆医科大学学报

Objective:To evaluate the effectiveness of intratumoral and intraperitoneal injection with retrovirus HSVtk gene on mouse bladder cancer.Methods:Subcutaneous and intraperitoneal bladder tumor was respectively established with mouse cancer cell line(T739) in syngeneic mice.Direct intratumor injection of retroviral HSVtk into the subcutaneous tumor was performed.In peritoneum cavity tumor model,HSVtk gene was transferred by intraperitoneal injection of retrovirus vector carrying HSVtk gene.After GCV therapy the tumor volume and animal survival time were monitored.Results:Both animal models were successfully induced in all mice within one week following subcutaneous and intraperitoneal injection of T739 cells.Compared with control animals,the tumor growth in both models was significantly inhibited with HSVtk/GCV system,and also the animal survival time was prolonged with administration of GCV(P