A survey: potential impact of genetically modified maize tolerant to drought or resistant to stem borers in Uganda

Maize production in Uganda is constrained by various factors, but especially drought and stem borers contribute to significant yield losses. Genetically modified (GM) maize with increased drought tolerance and/or Bt insect resistance (producing the Bacillus thuringiensis Cry protein) is considered as an option. For an ex ante impact analysis of these technologies, a farmer survey was carried out in nine districts of Uganda, representing the major farming systems. The results showed that farmers did rate stem borer and drought as the main constraints for maize farming. Most farmers indicated a positive attitude towards GM maize, and 86% of all farmers said they would grow GM maize. Farmer estimated yield losses to drought and stem borer damage were on average 54.7% and 23.5%, respectively, if stress occurred. Taking the stress frequency into consideration (67% for both), estimated yield losses were 36.5% and 15.6% for drought and stem borer, respectively. According to the ex-ante partial budget analysis, Bt hybrid maize could be profitable, with an average value/cost ratio of 2.1. Drought tolerant hybrid maize had lower returns and a value/cost ratio of 1.5. Negative returns occurred mainly for farmers with non-stressed grain yields below 2 t·ha−1. The regulatory framework in Uganda needs to be finalized with consideration of strengthening key institutions in the maize sector for sustainable introduction of GM maize.Isaac M. Wamatsembe, Godfrey Asea and Stephan M. Haefel

Characterization of elite maize inbred lines for drought tolerance using Simple Sequence Repeats markers

The development of drought tolerant maize has been limited by the suggested complexity of the environment on drought phenotypic traits. However, some simple sequence repeats (SSRs) molecular markers linked to drought tolerance via quantitative trait loci (QTL) have been identified in maize but their use requires validation on newly developed elite maize inbred lines. This study therefore aims to validate 19 selected SSR markers linked to maize drought tolerance and determine the genetic diversity of sixty-eight elite maize inbred lines. Genomic DNA was extracted with a CTAB method and the PCR products were separated on agarose gel with auto radiograms visually scored for polymorphic bands to establish a data matrix. Assessment of the genetic links among the inbred lines was carried out using cluster analysis. The 68 maize inbred lines were clustered based on a matrix of genetic similarity Jaccard using the UPGMA algorithm. Some of the markers that were informative included P-bnlg238, Phi037, P-bnlg1179 and Umc2214 and these showed significant group differentiation among the inbred lines. Marker Umc1447, Umc1432 and Umc2359 were among the markers with monomorphic bands, while Phi034, Bnlg1074 and P-umc1542 showed no characterized bands. The polymorphism information content (PIC) value of the informative markers ranged from 0.13 (Bnlg434) to 0.76 (P-bnlg238). The cluster analysis classified the maize inbred lines into four groups based on the SSR data. The exploitation of information of genetic diversity among the inbred maize lines to develop drought tolerant hybrids is hereby discussed

Lending Cycles

We investigate the lending behavior of banks by exploiting a rich panel dataset on the contract terms of approximately two million commercial and industrial loans granted by 580 banks between 1977-1993. Using a Markov switching panel model we demonstrate that banks change their lending standards from tightness to laxity systematically over the cycle. We then use an efficient minimum chi-square estimator to examine the relationship between the cyclical component of aggregate unemployment and bank lending standards when both variables are jointly endogenously determined in a system of simultaneous equations with mixed, continuous/discrete dependent variables. The patterns we uncover suggest that lax lending standards that tend to occur during expansions exert considerable influence on the dynamics of aggregate fluctuations.

A mouse model for triple-negative breast cancer tumor-initiating cells (TNBC-TICs) exhibits similar aggressive phenotype to the human disease

<p>Abstract</p> <p>Background</p> <p>Triple-negative breast cancer (TNBC) exhibit characteristics quite distinct from other kinds of breast cancer, presenting as an aggressive disease--recurring and metastasizing more often than other kinds of breast cancer, without tumor-specific treatment options and accounts for 15% of all types of breast cancer with higher percentages in premenopausal African-American and Hispanic women. The reason for this aggressive phenotype is currently the focus of intensive research. However, progress is hampered by the lack of suitable TNBC cell model systems.</p> <p>Methods</p> <p>To understand the mechanistic basis for the aggressiveness of TNBC, we produced a stable TNBC cell line by sorting for 4T1 cells that do not express the estrogen receptor (ER), progesterone receptor (PgR) or the gene for human epidermal growth factor receptor 2 (HER2). As a control, we produced a stable triple-positive breast cancer (TPBC) cell line by transfecting 4T1 cells with rat HER2, ER and PgR genes and sorted for cells with high expression of ER and PgR by flow cytometry and high expression of the HER2 gene by Western blot analysis.</p> <p>Results</p> <p>We isolated tumor-initiating cells (TICs) by sorting for CD24⁺/CD44^high/ALDH1⁺cells from TNBC (TNBC-TICs) and TPBC (TPBC-TICs) stable cell lines. Limiting dilution transplantation experiments revealed that CD24⁺/CD44^high/ALDH1⁺cells derived from TNBC (TNBC-TICs) and TPBC (TPBC-TICs) were significantly more effective at repopulating the mammary glands of naïve female BALB/c mice than CD24^-/CD44^-/ALDH1^-cells. Implantation of the TNBC-TICs resulted in significantly larger tumors, which metastasized to the lungs to a significantly greater extent than TNBC, TPBC-TICs, TPBC or parental 4T1 cells. We further demonstrated that the increased aggressiveness of TNBC-TICs correlates with the presence of high levels of mouse twenty-five kDa heat shock protein (Hsp25/mouse HspB1) and seventy-two kDa heat shock protein (Hsp72/HspA1A).</p> <p>Conclusions</p> <p>Taken together, we have developed a TNBC-TICs model system based on the 4T1 cells which is a very useful metastasis model with the advantage of being able to be transplanted into immune competent recipients. Our data demonstrates that the TNBC-TICs model system could be a useful tool for studies on the pathogenesis and therapeutic treatment for TNBC.</p

Extracellular Hsp72 concentration relates to a minimum endogenous criteria during acute exercise-heat exposure

Extracellular heat-shock protein 72 (eHsp72) concentration increases during exercise-heat stress when conditions elicit physiological strain. Differences in severity of environmental and exercise stimuli have elicited varied response to stress. The present study aimed to quantify the extent of increased eHsp72 with increased exogenous heat stress, and determine related endogenous markers of strain in an exercise-heat model. Ten males cycled for 90 min at 50% O2peak in three conditions (TEMP, 20°C/63% RH; HOT, 30.2°C/51%RH; VHOT, 40.0°C/37%RH). Plasma was analysed for eHsp72 pre, immediately post and 24-h post each trial utilising a commercially available ELISA. Increased eHsp72 concentration was observed post VHOT trial (+172.4%) (P<0.05), but not TEMP (-1.9%) or HOT (+25.7%) conditions. eHsp72 returned to baseline values within 24hrs in all conditions. Changes were observed in rectal temperature (Trec), rate of Trec increase, area under the curve for Trec of 38.5°C and 39.0°C, duration Trec ≥ 38.5°C and ≥ 39.0°C, and change in muscle temperature, between VHOT, and TEMP and HOT, but not between TEMP and HOT. Each condition also elicited significantly increasing physiological strain, described by sweat rate, heart rate, physiological strain index, rating of perceived exertion and thermal sensation. Stepwise multiple regression reported rate of Trec increase and change in Trec to be predictors of increased eHsp72 concentration. Data suggests eHsp72 concentration increases once systemic temperature and sympathetic activity exceeds a minimum endogenous criteria elicited during VHOT conditions and is likely to be modulated by large, rapid changes in core temperature

APPLICATION OF MORPHO-ANATOMICAL TRAITS OF MAIZE PLANT TO QUALITY CONTROL AND QUALITY ASSURANCE IN MAIZE SEED SYSTEM

Good seed quality can be obtained through control of the entire seed production process. There are emerging issues in the seed sector due to seed quality in market. In many countries seed and planting materials available to farmers are often of insufficient quality, thus undermining the potential performance of crops. The objective this study was to use morpho-anatomical traits to determine the levels of maize hybrid seed purity on the market in Uganda. A total of 120 samples of four popular commercial maize hybrid were collected from agro-dealers in 13 districts, representing 3 seed companies\u2019 distribution network. The samples were planted and evaluated based on their descriptors, using an Alpha Lattice Design, with two replications at the National Crops Resources Research Institute (NaCRRI), Namulonge. Data were collected for 33 morpho-anatomical traits. Results showed significant (P&lt;0.05) differences within hybrids, and sources of seed among districts. Among the test materials, only Longe 9H had no significant (P&lt;0.05) difference within traits but others had some levels of significant (P&lt;0.05) differences. The principal component analysis of quantitative traits resulted in four components for each variety, with the explanation total of 53.3% for Longe 6H, 51.1% for Longe 7H, and 92.8% for Longe 9H and 39.1% for Longe 10%. There were varying levels of contamination of commercial hybrids based on morphoanatomical traits diversity within hybrids, compared to their descriptors for the traits evaluated. Hence, there is need to strengthen the quality control sub-sector for improved productivity at farmer levels.Des semences de bonne qualit\ue9 peuvent \ueatre obtenues en exer\ue7ant un control syst\ue9matique sur chacun des maillons du syst\ue8me de production semenci\ue8re. Le secteur semencier conna\ueet de plus en plus de difficult\ue9s, et ceci en raison de la qualit\ue9 des semences sur le march\ue9. Dans plusieurs pays, les semences disponibles pour les producteurs sont souvent de qualit\ue9 non satisfaisante, reduisant ainsi la performance des cultures. L\u2019objectif de l\u2019\ue9tude \ue9tait de se servir des caract\ue8res morpho-anatomiques afin de determiner le niveau purit\ue9 des semences de ma\uefs hybride sur le march\ue9 semencier en Ouganda. Au total 120 \ue9chantillons des quatre vari\ue9t\ue9es commerciales populaires de ma\uefs hybride ont \ue9t\ue9 collect\ue9s chez les distributeurs de semences dans 13 districts, repr\ue9sentant les r\ue9seaux de distribution de 3 compagnies semenci\ue8res. Les \ue9chantillons ont \ue9t\ue9 sem\ue9s et \ue9valu\ue9s en se basant sur leurs descripteurs. Le dispositive exp\ue9rimental Alpha Lattice a \ue9t\ue9 utilis\ue9, avec deux r\ue9p\ue9titions \ue0 l\u2019institut national de recherche des ressources culturales (NaCRRI), Namulonge. Les donn\ue9es de 33 caract\ue8res morphoanatomiques ont \ue9t\ue9 collect\ue9es. Les r\ue9sultats ont montr\ue9 des differences significatives (P&lt;0,05) ont \ue9t\ue9 observ\ue9es parmi les hybrides, ainsi que les sources des semences au sein des districts. Parmi les mat\ue9riels test\ue9s, seul Longe 9H n\u2019avait exhib\ue9 aucune difference significative (P&lt;0,05) des caract\ue8res \ue9valu\ue9s, mais certains ont des differences significatives \ue0 (P&lt;0,05). l\u2019analyse en composntes principales des traits quantitatifs a montr\ue9 quatre composantes pour chaque vari\ue9t\ue9, avec l\u2019ensemble de ces composantes expliquant 53,3% de la variation totale pour Longe 6H, 51,1% pour Longe 7H, 92,8% pour Longe 9H et 39,1% pour Longe 10%. Les niveaux de contamination \ue9taient variables, sugg\ue9rant la n\ue9cessit\ue9 de renforcer le sous-secteur de control de qualit\ue9 en vue d\u2019une meilleure productivit\ue9 au niveau des producteurs