Failure to reduce an isolated Blowfly population by the sterile males method

In 1956 and 1957 pupae of L. sericata were irradiated at 6,000–7,000 rep, and allowed to emerge at three points on Holy Island. The sterilized population was maintained in preponderant numbers by regular replenishments. A test in 1958 showed no reduction in the density of the species. Possible causes of failure of the method are examined, and it is concluded that either the sterilization was inadequate or that the sterilized males were unable to compete with the native males.

---

Zusammenfassung Die Methode sterile Männchen zur Ausrottung einer Art zu benutzen, ist in ihrer Wirkung mathematisch zuverlässig, vorausgesetzt, daß die anerkannten biologischen Erfordernisse vorhanden sind; sie hat sich in der Praxis gegen Callitroga bominivorax (Myiasisfliege) als wirksam erwiesen. In einem in kleinen Maßstabe durchgeführten Versuch gegen die Goldfliege Lucilia sericata wurden Fliegen, die durch eine 6,000–7,000 rep Gamma-Strahlung sterilisiert worden waren, in überwiegenden Zahlen auf einer 5 km² großen Insel in zwei aufeinanderfolgenden Jahren freigelassen. Eine Reduktion der einheimischen L. sericata-Population ließ sich nicht nachweisen. Es wurde experimentell geprüft, daß eine Zuwanderung von Fliegen vom Festland zu vernachlässigen war; wiederholte Versuche bestätigten, daß die Bestrahlungsdosis ausreichte, um sexuelle Sterilität zu erzeugen. Der Ablauf und die technischen Einzelheiten der Versuche wurden analysiert in dem Bestreben, die Ursache des Versagens ausfindig zu machen.Das Verhältnis steriler zu eingeborenen Männchen könnte im ersten Jahr infolge hoher Mortalität der sterilisierten Puppen under die erwartete Relation 5 : 1 gesunken sein. Diese Mortalität stand offenbar mit der Zuchtmethode in Beziehung. Es wurde jedoch gefolgert, daß dies an sich nicht für das Versagen verantwortlich gemacht werden könnte.Er wird vorläufig angenommen, daß hier, als Ergebnis von Sauerstoffmangel, ein geringer aber signifikanter Grad von Resistenz gegen Bestrahlung vorliege, möglicherweise begleitet von einer ähnlich geringgradigen Erholungsfähigkeit von Strahlungswirkungen; andererseits versagte das sterilisierte Sperma in Konkurrenz mit fertilem Sperma bei Doppelbegattungen.

     

Assessing internet survey data collection methods with ethnic nurse shift workers

An increasing number of ethnic minorities are expected to enter the United States workforce based on projected demographic changes. This includes American Indian/Alaskan Native (AI/AN) nurses. Sociocultural influences on sleep disturbances, sleepiness, and other aspects related to shift-work tolerance are of unrecognized importance. More minority nurses are needed to provide culturally congruent care; however, AI/AN nurses represent less than 1% of nurses located throughout the American workforce. This article aims to verify the feasibility of Internet data collection (Web-based survey) methods and instrument stability as the first part of a two-phase study comparing individual differences and shift-work-related sleep disturbances between AI/AN and White non-Hispanic (WNH) nurses. In the first phase, an Internet survey was used to reach a cross-section of AI/AN and WNH nurses. The on-line survey was composed of accepted shift-work-related instruments. Items estimating sleep disturbances, sociocultural choices, time awareness, polychronicity, morningness/eveningness, ethnic identity, and demographic questions were asked. The survey was linked to a series of Web pages describing the study purpose, inclusion and exclusion criteria, consent form, Web survey, and the second phase of the study in which subjects were invited to participate in actigraphy measurements. The survey was pilot-tested for error codes, item confusion, length, and completion time. Forced-answer questions were added asking ethnicity, age group, license type, state where licensed, and legal name on nursing license before accessing the survey. Data were saved periodically, cued by the word “continue.” The database was located on a secure server and password protected. Nurses were recruited using published articles and printed advertisements, hospital e-mail systems, national nursing organization Web sites (minoritynurse.com; NANAINA.org), nursing Web site discussion groups, snow-balling, and word of mouth. The site was accessed 656 times with the Internet survey being completed by 138 WNH and 56 AI/AN nurses meeting the inclusion criteria. Except for the polychronicity measure (PAI3), instruments measuring time awareness, chronotype, and situational sleepiness achieved acceptable reliability coefficients with Internet data collection. Using pull-down menus would improve questions asking specific times. Internet data collection with different ethnic groups is possible; however, accessing the target population may be difficult. Despite extensive recruitment efforts, few AI/AN nurses participated. Computer literacy and failing to relate to the study's purpose may have limited the interest of the AI/AN nurses. It is possible to recruit nurse shift workers and collect individual difference and sleep disturbance data through the Internet; however, the researcher must remain vigilant throughout the process.     

Accelerated onset of heart failure in mice during pressure overload with chronically decreased SERCA2 calcium pump activity

We recently developed a mouse model with a single functional allele of Serca2 (Serca2+/-) that shows impaired cardiac contractility and relaxation without overt heart disease. The goal of this study was to test the hypothesis that chronic reduction in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA)2 levels in combination with an increased hemodynamic load will result in an accelerated pathway to heart failure. Age-matched wild-type and Serca2+/- mice were subjected to 10 wk of pressure overload via transverse aortic coarctation surgery. Cardiac hypertrophy and heart failure were assessed by echocardiography, gravimetry/histology, hemodynamics, and Western blotting analyses. Our results showed that approximately 64% of coarcted Serca2+/- mice were in heart failure compared with 0% of coarcted wild-type mice (P < 0.05). Overall, morbidity and mortality were greatly increased in Serca2+/- mice under pressure overload. Echocardiography assessment revealed a significant increase in left ventricular (LV) mass, and LV hypertrophy in coarcted Serca2+/- mice converted from a concentric to an eccentric pattern, similar to that seen in human heart failure. Coarcted Serca2+/- mice had decreased contractile/systolic and relaxation/diastolic performance and/or function compared with coarcted wild-type mice (P < 0.05), despite a similar duration and degree of pressure overload. SERCA2a protein levels were significantly reduced (>50%) in coarcted Serca2+/- mice compared with noncoarcted and coarcted wild-type mice. Our findings suggest that reduction in SERCA2 levels in combination with an increased hemodynamic load results in an accelerated pathway to heart failure.     

The Rb tumor suppressor is required for stress erythropoiesis

The retinoblastoma tumor suppressor gene plays important roles in cell cycle control, differentiation and survival during development and is functionally inactivated in most human cancers. Early studies using gene targeting in mice suggested a critical role for pRb in erythropoiesis, while more recent experiments have suggested that many of the abnormal embryonic phenotypes in the Rb null mouse result from a defective placenta. To address this controversy and determine whether Rb has cell intrinsic functions in erythropoiesis, we examined the effects of Rb loss on red cell production following acute deletion of pRb in vitro and under different stress conditions in vivo. Under stress conditions, pRb was required to regulate erythroblast expansion and promote red cell enucleation. Acute deletion of Rb in vitro induced erythroid cell cycle and differentiation defects similar to those observed in vivo. These results demonstrate a cell intrinsic role for pRb in stress erythropoiesis and hematopoietic homeostasis that has relevance for human diseases.     

Intermediate filaments mediate cytoskeletal crosstalk

Intermediate filaments, actin-containing microfilaments and microtubules are the three main cytoskeletal systems of vertebrate and many invertebrate cells. Although these systems are composed of distinctly different proteins, they are in constant and intimate communication with one another. Understanding the molecular basis of this cytoskeletal crosstalk is essential for determining the mechanisms that underlie many cell-biological phenomena. Recent studies have revealed that intermediate filaments and their associated proteins are important components in mediating this crosstalk.