Single-molecule investigation of G-quadruplex folds of the human telomere sequence in a protein nanocavity.

Human telomeric DNA consists of tandem repeats of the sequence 5'-TTAGGG-3' that can fold into various G-quadruplexes, including the hybrid, basket, and propeller folds. In this report, we demonstrate use of the α-hemolysin ion channel to analyze these subtle topological changes at a nanometer scale by providing structure-dependent electrical signatures through DNA-protein interactions. Whereas the dimensions of hybrid and basket folds allowed them to enter the protein vestibule, the propeller fold exceeds the size of the latch region, producing only brief collisions. After attaching a 25-mer poly-2'-deoxyadenosine extension to these structures, unraveling kinetics also were evaluated. Both the locations where the unfolding processes occur and the molecular shapes of the G-quadruplexes play important roles in determining their unfolding profiles. These results provide insights into the application of α-hemolysin as a molecular sieve to differentiate nanostructures as well as the potential technical hurdles DNA secondary structures may present to nanopore technology.

Meta-Analysis of Herbicide Non-Target Effects on Pest Natural Enemies.

A critical component of integrated pest management is minimizing disruption of biological control by reducing the use of pesticides with significant non-target effects on natural enemies. Insecticide non-target effects testing for natural enemies has become increasingly common, but research examining the non-target effects of herbicides on natural enemies is scarce, and recommendations regarding herbicide selectivity are non-existent. We used meta-analysis to summarize laboratory bioassays testing non-target effects of herbicides on arthropod natural enemies and identify patterns in taxon susceptibility and active ingredient toxicity. Data were extracted from 78 papers representing 801 total observations. Herbicides increased natural enemy mortality and decreased longevity, reproduction, and predation. Mesostigmatan mites and hemipterans were the most sensitive to herbicides, and spiders, neuropterans, and hymenopterans were the least sensitive. Mortality was higher in juvenile predators versus parasitoids but did not differ between adults; parasitoid juveniles are likely better protected within the host. In terms of acute mortality, metribuzin, glufosinate, and oxyfluorfen were the most harmful herbicides. Only nicosulfuron, rimsulfuron, pendimethalin, phenmedipham, atrazine, and urea did not increase natural enemy mortality. The large effect size of glufosinate is particularly concerning, as it is the most likely replacement herbicide for glyphosate in many crops. Many active ingredients remain under-studied. Our analysis indicates that herbicides have a strong potential to disrupt biological control in cropping systems.

Sanitizing Equipment and Personnel to Prevent the Spread of Hibiscus Mealybug [Nipaecoccus viridis (Hemiptera: Pseudococcidae)] in Florida Citrus.

Hibiscus mealybug (Nipaecoccus viridis, Newstead) is an emerging and serious pest of citrus in Florida. Preventing the spread of hibiscus mealybug by sanitizing personnel and equipment such as individual protective covers can help limit new infestations. Two mealybug life stages, first instars (crawlers) and eggs inside ovisacs, were tested as they are the most likely to be accidentally transported on people and tools. Isopropanol sprays in 3 commercially available concentrations (50%, 70%, and 90%) were tested against crawlers and ovisacs, and steam treatments and hot water immersion were tested against ovisacs. All concentrations of isopropanol resulted in >90% incapacitation of mealybug crawlers, especially when two sprays of isopropanol were applied. However, no concentration of isopropanol reliably killed all mealybug eggs within ovisacs. Steam treatments and hot water immersion for 10 min or longer at 49°C and for 5 min or longer at 54.5°C resulted in 100% mortality of mealybug adults and eggs inside ovisacs. However, adults and ovisacs insulated inside of individual protective covers did not experience 100% mortality until 30 min or longer at 49°C, 10 min or longer at 54.5°C, and 5 min or longer at 60°C for steam treatments. Isopropanol sprays can effectively incapacitate the majority of hibiscus mealybug crawlers on personnel and tools, but are not effective against ovisacs. Steam treatments and hot water immersion can reliably lead to 100% mortality of ovisacs, but longer times and higher temperatures must be used for steam treatments if ovisacs are insulated by equipment.

Floral Plantings in Large-Scale Commercial Agroecosystems Support Both Pollinators and Arthropod Predators.

Beneficial insect populations and the services that they provide are in decline, largely due to agricultural land use and practices. Establishing perennial floral plantings in the unused margins of crop fields can help conserve beneficial pollinators and predators in commercial agroecosystems. We assessed the impacts of floral plantings on both pollinators and arthropod predators when established adjacent to conventionally managed commercial potato fields. Floral plantings significantly increased the abundance of pollinators within floral margins compared with unmanaged margins. Increased floral cover within margins led to significantly greater pollinator abundance as well. The overall abundance of arthropod predators was also significantly increased in floral plantings, although it was unrelated to the amount of floral cover. Within adjacent potato crops, the presence of floral plantings in field margins had no effect on the abundance of pollinators or predators, although higher floral cover in margins did marginally increase in-crop pollinator abundance. Establishing floral plantings of this kind on a large scale in commercial agroecosystems can help conserve both pollinators and predators, but may not increase ecosystem services in nearby crops.

Exploring Leader Identity and Development.

Taking on a leader identity can be a motivating force for pursuing leader development. This chapter explores the reciprocal and recursive nature of identity development and leader development, emphasizing how shifting views of self influence one's motivation to develop as a leader.

A comprehensive medical student career development program improves medical student satisfaction with career planning.

In 1999, the University of Michigan Medical School (UMMS) initiated a new career development program (CDP). The CDP incorporates the 4-phase career development model described by the Association of American Medical Colleges (AAMC) Careers in Medicine (CiM). The CDP offers self-assessment exercises with guidance from trained counselors for 1st- and 2nd-year medical students. Career exploration experiences include Career Seminar Series luncheons, shadow experiences with faculty, and a shadow program with second-year (M2) and fourth-year (M4) medical students. During the decision-making phase, students work with trained faculty career advisors (FCA). Mandatory sessions are held on career selection, preparing the residency application, interviewing, and program evaluation. During the implementation phase, students meet with deans or counselors to discuss residency application and matching. An "at-risk plan" assists students who may have difficulty matching. The CiM Web site is extensively used during the 4 stages. Data from the AAMC and UMMS Graduation Questionnaires (GQ) show significant improvements for UMMS students in overall satisfaction with career planning services and with faculty mentoring, career assessment activities, career information, and personnel availability. By 2003, UMMS students had significantly higher satisfaction in all measured areas of career planning services when compared with all other U.S. medical students.