Type IV secretion (T4S) systems mediate the transfer of proteins and DNA across the cell envelope of bacteria. These systems play important roles in bacterial pathogenesis and in horizontal transfer of antibiotic resistance. The VirB4 ATPase of the T4S system is essential for both the assembly of the system and substrate transfer. In this article, we present the crystal structure of the Cterminal domain of Thermoanaerobacter pseudethanolicus VirB4. This structure is strikingly similar to that of another T4S ATPase, VirD4, a protein that shares only 12% sequence identity with VirB4. The VirB4 domain purifies as a monomer, but the full-length protein is observed in a monomer-dimer equilibrium, even in the presence of nucleotides and DNAs. We also report the negative stain electron microscopy structure of the core complex of the T4S system of the Escherichia coli pKM101 plasmid, with VirB4 bound. In this structure, VirB4 is also monomeric and bound through its N-terminal domain to the core's VirB9 protein. Remarkably, VirB4 is observed bound to the side of the complex where it is ideally placed to play its known regulatory role in substrate transfer. macromolecular assembly | structural biology | conjugation

Purpose -The purpose of this paper is to investigate the factors (farm, operator and household characteristics, along with farm type and regional location of the farm) affecting financial performance of new and beginning farmers and ranchers. Design/methodology/approach -Returns on assets (ROA), a measure of financial performance widely used in the farm management literature, is the ratio of net farm income plus interest payment to total assets. This measure has been used by Gloy and LaDue and Gloy et al. to measure financial performance of farmers in New York. ROA is hypothesized to be a function of operator/farm characteristics and management strategies used to manage the farm. The independent variables hypothesized to affect the farm's financial performance encompass the following three areas: farm operator characteristics, farm characteristics such as production and marketing efficiency measures, and management strategies. All standard errors were adjusted for heteroscedasticity using the Huber-White sandwich robust variance estimator based on algorithms contained in STATA. Findings -Results from this study show that although there is an inverted U-shaped relationship between age of the operator and financial performance, management strategies such as increasing the number of decision makers, engaging in value-added farming, and having a written business plan can lead to higher financial performance. Originality/value -More than 50 percent of current farmers are likely to retire in the next five years. US farmers over age 55 control more than half the farmland, while the number of new farmers replacing them has fallen since the Farm Crisis period, 1982Crisis period, -1987 Paralleling this shift in production, agriculture is in a decline in overall farm numbers. Concern in many states arises because the loss adversely affects the future of family farms, the farm economy and healthy rural communities. Additionally, the rapid decline in the entry of new and young farmers is an indication of rising barriers to entry, resulting in calls from within the farming community for public policy measures designed to aid new and beginning farmers.

Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 gg/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.

The Internet is becoming an increasingly important management tool in production agriculture. Using data from the 2004 Agricultural Resource Management Survey (ARMS) and a double-hurdle estimation approach, we explore the adoption of computers with Internet access by and Internet purchasing patterns of farm households. Adoption of the Internet is positively related to age and education of the operator, off-farm work, presence of spouse, participation in government programs, farm size, and regional location of the farm. Internet purchasing patterns of farm households are positively related to the education of the operator and spouse, presence of teenagers, and regional location of the farm. Finally, farm businesses and their households are more likely to purchase a greater percentage of non-durable goods through the Internet as distances to markets increase.

Prodigiosenes (prodigiosin and prodigiosin-like pigments) are known to be synthesized by only one genus of Eubacteriales and by two genera of Actinomycetales. Biosynthesis by Serratia marcqscens occurs over a relatively narrow range of temperatures, although the bacteria grow over a broad range. When cultures of S. marcescens were incubated at 27 C in 1.0% casein hydrolysate, viable count and protein attained maximal values within 24 to 48 h, whereas prodigiosin did not reach a maximum until 96 h. The greatest amount of pigment was synthesized when cultures were in the senescent phase of growth. Suspensions of nonproliferating bacteria incubated at 27 C in only i-alanine also synthesized prodigiosin, although at a slower rate than growing cultures. Kinetics of growth for the wild-type, red S. marcescens and a white mutant were identical when incubated at 27 C, but the wild type produced abundant pigment. These results plus other data obtained from the literature suggest that prodigiosin is a secondary metabolite. The importance of this proposal to understanding the function of prodigiosin in S. marcescens is discussed.