Hox Genes Regulate Muscle Founder Cell Pattern Autonomously and Regulate Morphogenesis Through Motor Neurons

The differentiation of myoblasts to form functional muscle fibers is a consequence of interactions between the mesoderm and ectoderm. The authors examine the role of segment identity in directing these interactions by studying the role of Hox genes in patterning adult muscles in Drosophila. Using the `four-winged fly' to remove Ultrabithorax function in the developing adult, the authors alter the identity of the ectoderm of the third thoracic segment towards the second and show that this is sufficient to inductively alter most properties of the mesoderm—myoblast number, molecular diversity, and migration pattern—to that of the second thoracic segment. Not all aspects of myogenesis are determined by the segment identity of the ectoderm. The autonomous identity of the mesoderm is important for choosing muscle founder cells in the correct segmental pattern. The authors show this by removal of the function of Antennapedia, the Hox gene expressed in the mesoderm of the third thoracic segment. This results in the transformation of founder cells to a second-thoracic pattern. The authors also report a role for the nervous system in later aspects of muscle morphogenesis by specifically altering Ultrabithorax gene expression in motor neurons. Thus, ectoderm and mesoderm segment identities collaborate to direct muscle differentiation by affecting distinct aspects of the process

Sequence analysis of the cis-regulatory regions of the bithorax complex of Drosophila

The bithorax complex (BX-C) of Drosophila, one of two complexes that act as master regulators of the body plan of the fly, has now been entirely sequenced and comprises approximate to 315,000 bp, only 1.4% of which codes for protein. Analysis of this sequence reveals significantly overrepresented DNA motifs of unknown, as well as known, functions in the nonprotein-coding portion of the sequence. The following types of motifs in that portion are analyzed: (i) concatamers of mono-, di-, and trinucleotides; (ii) tightly clustered hexanucleotides (spaced less than or equal to 5 bases apart); (iii) direct and reverse repeats longer than 20 bp; and (iv) a number of motifs known from biochemical studies to play a role in the regulation of the BX-C. The hexanucleotide AGATAC is remarkably overrepresented and is surmised to play a role in chromosome pairing. The positions of sites of highly overrepresented motifs are plotted for those that occur at more than five sites in the sequence, when <0.5 case is expected. Expected values are based on a third-order Markov chain, which is the optimal order for representing the BXCALL sequence

Interview with Edward B. Lewis

A 1984 interview in two sessions with Edward B. Lewis, then the Thomas Hunt Morgan Professor of Biology at Caltech. Dr. Lewis would be awarded the 1995 Nobel Prize in physiology or medicine, along with Christiane Nüsslein-Vollhard and Eric F. Wieschaus, for discoveries concerning "the genetic control of early embryonic development." In this interview, he recalls how he and a colleague, Edward Novitski (who would also receive a Caltech PhD), acquired stocks of Drosophila melanogaster while they were still high school students in Wilkes-Barre, Pennsylvania. In 1939, after a year at Bucknell on a music scholarship and only two years at the University of Minnesota, Lewis received his bachelor's degree (in biostatistics), whereupon he entered Caltech as a graduate student. Working under A. H. Sturtevant, he continued his Drosophila studies, receiving his PhD in genetics in 1942. After a wartime stint as a meteorologist in the Army Air Forces, Dr. Lewis returned to Caltech as an instructor in the Division of Biology in 1946. He became a full professor in 1956 and the Morgan Professor in 1966. He recalls the early days of genetics at Caltech and offers his recollections of Thomas Hunt Morgan, chair of the division from 1928 to 1942, and of Sturtevant and Theodosius Dobzhansky. He comments on the state of the Biology Division after Morgan's retirement and on the arrival of George W. Beadle as division chairman in 1946. He describes his work on the Drosophila bithorax complex of genes and also on the somatic effects of radiation on human beings and his part in the controversy over nuclear testing in the late 1950s and early 1960s. He recalls the visit of four geneticists from the Soviet Union in 1967. He concludes by commenting briefly on the changes in the field of genetics since the discovery of the genetic material and on his current work on the phenomenon of transvection. Dr. Lewis became emeritus in 1988 and died on July 21, 2004

Report on Transfer Tax Restructuring

This report is submitted to the Council of the Section of Taxation, American Bar Association as a proposed response to the request of the Treasury Department for suggestions for reform of the Federal transfer taxes (the estate, gift, and generation-skipping transfer taxes). That request was contained in a letter dated November 19, 1985, from Ronald A. Pearlman, the Assistant Secretary (Tax Policy), to Hugh Calkins, then Section Chair.\u27 After receiving individual comment papers on the subject from members of the Section\u27s Committee on Estate and Gift Taxes, Mr. Calkins, on April 14, 1986, created this Task Force and asked it to prepare a more fundamental response

Stress and stressors experienced by the parents of high-risk neonates admitted in neonatal intensive care unit: Systematic review and meta-analysis evidence available from India

The aim of the systematic review and meta-analysis is to determine the stress and stressors experienced by the parents of high-risk neonates admitted to the neonatal intensive care unit (NICU) in India. We included both quantitative and qualitative studies. The Joanna Briggs Institute Critical Appraisal Checklist and Critical Appraisal Skill Programme checklist were used to assess the quality of included studies. A systematic search was conducted in PubMed, EMBASE, SCOPUS, EBSCOhost, Web of Science, ProQuest, Microsoft Academic, DOAJ, Indian Citation Index, and J-Gate to identify relevant studies. Additionally, online hand searching was performed on Indian websites of relevant institutions, women and child health departments, repositories, registries, and paediatric journals. Twelve of the 21 quantitative studies found that maternal stress was higher than fathers due to the separation from their babies and the medical condition of the neonate. One qualitative study reported that financial burden, alterations in the parenting role, and concern over domestic issues are significant causes of fathers' stress. A meta-analysis of the included studies assessed the prevalence of maternal, paternal, and parental stress and reported that mothers experienced higher stress levels than fathers across all subscales. The most typical stressors for parents were changes in neonatal looks, behaviour, and altered parental roles. Beyond the immediate NICU care and interactions, other triggering factors of stress among parents must be considered to design multicomponent interventions in a local (Indian) context. Moreover, parental psychological support and regular counselling can be incorporated into the standard neonatal intensive care policy

Civil conflict, federalism and strategic delegation of leadership

This article analyzes negative externalities that policymakers in one region or group may impose upon the citizens of neighboring regions or groups. These externalities may be material, but they may also be psychological (in the form of envy). The latter form of externality may arise from the production of 'conspicuous' public goods. As a result, decentralized provision of conspicuous public goods may be too high. Potentially, a centralized legislature may internalize negative externalities. However, in a model with strategic delegation, we argue that the median voter in each jurisdiction may anticipate a reduction in local public goods supply and delegate to a policymaker who cares more for public goods than she does herself. This last effect mitigates the expected benefits of policy centralization. The authors' theory is then applied to the setting of civil conflict, where they discuss electoral outcomes in Northern Ireland and Yugoslavia before and after significant institutional changes that affected the degree of centralization. These case studies provide support for the authors' theoretical predictions