K-State Research Exchange

Molecular characterization of digestive proteases of the yellow mealworm, Tenebrio molitor L.

Fri, 09 Jun 2006 14:43:42 GMT

Title: Molecular characterization of digestive proteases of the yellow mealworm, Tenebrio molitor L.

Authors: Prabhakar, Sheila

Abstract: Coleopteran insects compensate for dietary protease inhibitors by a number of mechanisms. To study this compensation response at the molecular level, the digestive proteases of Tenebrio molitor were studied. Biochemical studies of the pH optima and inhibitor sensitivity of proteases indicated the cysteine proteases were mostly in the anterior and serine proteases were in the posterior midgut of T. molitor larvae. Expressed Sequence Tags (ESTs) from T. molitor larval midgut cDNA libraries contained sequences encoding putative digestive proteases. Of a total of 1,528 cDNA sequences, 92 cDNAs encoded proteases, and 50 full-length cDNAs were grouped into serine, cysteine and metallo protease classes. Sequences tmt1a, tmt1b and tmt1c were identified as genes encoding isoforms of T. molitor trypsin, and tmc1a encoded T. molitor chymotrypsin. The general distribution cysteine protease transcripts in the anterior and serine protease transcripts in the posterior midgut, of T. molitor larvae, was in agreement with the biochemically-characterized compartmentalization of proteases. Expression analyses of selected transcripts demonstrated varied expression patterns across five developmental stages of T. molitor, with maximal expression of most protease transcripts in first instar larvae. Dietary serine and cysteine protease inhibitors fed in combination to early-instar T. molitor larvae caused a significant delay in larval growth in 21-day-old larvae. Real-time quantitative PCR analysis of RNA isolated from larvae fed different protease inhibitor treatments indicated that dietary inhibitors affected the expression of serine and cysteine proteases. Larvae fed soybean trypsin inhibitor, a serine protease inhibitor, compensated by the hyperproduction of proteases from the same class, as well as the upregulation of cysteine proteases. A cysteine protease inhibitor, E-64, caused a reduction in the hyperproduction of all proteases, and, in combination with the soybean trypsin inhibitor, lowered the compensation response of T. molitor larvae to negligible levels. These data suggest that T. molitor larvae are more sensitive to the effects of cysteine protease inhibitors, perhaps because these proteases are the first line of defense for larvae against plant protease inhibitor. The bioassay and molecular studies suggested that combinations of inhibitors that target both serine and cysteine proteases are needed to effectively control larval infestations of T. molitor.

MPH Field Experience

Thu, 05 Nov 2009 17:43:35 GMT

Title: MPH Field Experience

Authors: McGill, Zachary

Abstract: The following documents are a collection of products finished by Kansas State University graduate student Zachary McGill in support for his master’s degree in public health. The student had a field experience at three different sites; the Kansas Health Institute, the Kansas Public Health Association, and the Network for a Healthy California, Los Angeles Region. The student was able to gain experience in by working on public health, community events, grant writing, article writing, research, and policy at all three sites.

THE ECONOMIC DETERMINANTS OF THE NUMBER OF MINORITY FARMERS IN THE SOUTHERN REGION OF THE UNITED STATES, 1969-1997

Thu, 05 Nov 2009 15:01:55 GMT

Title: THE ECONOMIC DETERMINANTS OF THE NUMBER OF MINORITY FARMERS IN THE SOUTHERN REGION OF THE UNITED STATES, 1969-1997

Authors: Luster, Tonshia

Abstract: The primary purpose of this research was to identify and quantify the determinants of the number of minority farms in the Southern region of the United States during the time period, 1969-1997. A second objective was to determine the impact of globalization and international trade agreements on the number of African-American farmers in the Southern region of the United States. Regression results indicate that minority farm labor was responsive to the returns to agriculture labor relative to nonfarm labor returns, as well as to cotton and rice prices. Increase in the cotton price increased minority farmer income, slowing the rate of agricultural migration from the Southern region of the United States. To the extent that globalization results in lower cotton prices, international agricultural trade agreements are likely to result in further movement of minority farmers out of agriculture in the Southern region of the United States.

Mowing and drought effects on a hybrid bluegrass compared with a Kentucky bluegrass

Wed, 04 Nov 2009 15:10:44 GMT

Title: Mowing and drought effects on a hybrid bluegrass compared with a Kentucky bluegrass

Authors: Su, Kemin; Bremer, Dale J.; Keeley, Steven J.; Fry, Jack D.

Abstract: Hybrid bluegrasses (HBG) resemble Kentucky bluegrass (Poa pratensis L.)(KBG) but HBG may have greater heat and drought tolerance. Little is known about the performance of HBG under low mowing heights and during drought. A two-year field study was conducted near Manhattan, Kansas, USA to investigate effects of mowing and drought on visual quality and gross canopy photosynthesis (Pg) in a KBG (‘Apollo’) and HBG (‘Thermal Blue’). Treatments included three main factors at two levels each: 1) species (Apollo, Thermal Blue); 2) mowing height (7.6 cm or 3.8 cm); and 3) irrigation (100% [well watered] and 60% [drought] evapotranspiration [ET] replacement). Visual quality in Thermal Blue was similar to or lower than Apollo during both years. Visual quality and Pg declined at the lower mowing height in both species in 2004 and in Thermal Blue in 2005, but visual quality in Apollo improved slightly in 2005 including under drought. At the lower mowing height, visual quality in Thermal Blue was nine to 15% lower than Apollo in 2005, perhaps because KBG had greater leaf area and extracted more soil moisture than Thermal Blue. When well watered, Pg was lower in Thermal Blue than in Apollo but differences converged as drought progressed. Drought reduced visual quality of both grasses during both years. Data suggest that Apollo may be better suited than Thermal Blue as a turfgrass selection for the transition zone. Further research is needed to identify new cultivars of HBG that may perform better than KBG at low mowing and during drought.