The \u3ci\u3eDrosophila\u3c/i\u3e T-box Transcription Factor Midline Functions Within the Notch-Delta Signaling Pathway To Specify Sensory Organ Precursor Cell Fates and Regulates Cell Survival Within the Eye Imaginal Disc

We report that the T-box transcription factor Midline (Mid), an evolutionary conserved homolog of the vertebrate Tbx20 protein, functions within the Notch-Delta signaling pathway essential for specifying the fates of sensory organ precursor (SOP) cells. These findings complement an established history of research showing that Mid regulates the cell-fate specification of diverse cell types within the developing heart, epidermis and central nervous system. Tbx20 has been detected in unique neuronal and epithelial cells of embryonic eye tissues in both mice and humans. However, the mechanisms by which either Mid or Tbx20 function to regulate cell-fate specification or other critical aspects of eye development including cell survival have not yet been elucidated. We have also gathered preliminary evidence suggesting that Mid may play an indirect, but vital role in selecting SOP cells within the third-instar larval eye disc by regulating the expression of the proneural gene atonal. During subsequent pupal stages, Mid specifies SOP cell fates as a member of the Notch-Delta signaling hierarchy and is essential for maintaining cell viability by inhibiting apoptotic pathways. We present several new hypotheses that seek to understand the role of Mid in regulating developmental processes downstream of the Notch receptor that are critical for specifying unique cell fates, patterning the adult eye and maintaining cellular homeostasis during eye disc morphogenesis. © 2013 Elsevier Ireland Ltd

The Role of Midline and Pexin10 in Regulating \u3ci\u3eDrosophila\u3c/i\u3e Eye Development

The Drosophila midline (mid) transcription factor gene encodes a highly conserved invertebrate ortholog of the mammalian Tbx20 gene essential for regulating the development of diverse tissues including the central nervous system (CNS), epidermis and heart. Decreasing mid transcript levels within larval eye discs using RNAi (mid- RNAi) results in poorly organized IPCs and in adult eyes, interommatidal bristles derived from sensory organ precursors are significantly reduced in number within the ventral eye field. We also observe gross abnormalities in bristle polarity, ommatidial organization, cellular adhesion and pigmentation in adult mid-RNAi flies. By combining a classical genetic modifier screen with the established RNAi methods, we set out to identification mid-interacting genes and from this screen found that mid potentially interacts with members of the pexin gene family. Pexin proteins are critical for regulating peroxisome structure and function. Placing heterozygous mutant alleles of several pexin genes within the mid-RNAi background did not enhance or suppress the mutant bristle phenotype. However, we found that overexpressing pexin10 in the mid-RNAi genetic background nearly complete suppressed or rescued the mutant bristle phenotype. These results suggest that peroxisomal functions are compromised in cells of mid-RNAi larval eye discs since expression of a critical pexin gene, pexin10, recovered the cells to their wild- type morphologies. Future research will elucidate how mid functions to regulate peroxisome function

Manikin measurements of the noise attenuation provided by flight helmets /

Measurements of the noise attenuation provided by five flight helmets were obtained on a manikin head and compared with attenuation measurements obtained on human subjects according to the USASI Standard for Evaluating Real-Ear Attenuation at Threshold. The two sets of measurements were similar. The manikin method has certain advantages which should be considered in terms of the particular requirements of an evaluation program: (1) a helmet can be optimally fitted with little expenditure of time; (2) variability introduced by human factors is kept at a minimum; (3) high levels of noise can be used as the test stimulus; (4) visual and auditory monitoring of the attenuated noise provides the experimenter with a precise appraisal of the fit as adjustments are made; (5) manikin measurements are particularly useful in revealing improvements in attenuation resulting from minor modifications. (Author)."Bureau of Medicine and Surgery, MF 12.524.005-5020.1, Naval Air Systems Command A34-531-561/69F12524404."--title page."23 August 1968."Measurements of the noise attenuation provided by five flight helmets were obtained on a manikin head and compared with attenuation measurements obtained on human subjects according to the USASI Standard for Evaluating Real-Ear Attenuation at Threshold. The two sets of measurements were similar. The manikin method has certain advantages which should be considered in terms of the particular requirements of an evaluation program: (1) a helmet can be optimally fitted with little expenditure of time; (2) variability introduced by human factors is kept at a minimum; (3) high levels of noise can be used as the test stimulus; (4) visual and auditory monitoring of the attenuated noise provides the experimenter with a precise appraisal of the fit as adjustments are made; (5) manikin measurements are particularly useful in revealing improvements in attenuation resulting from minor modifications. (Author).Mode of access: Internet

Slavery and Plantation Capitalism in Louisiana's Sugar Country

Sugar planters in the antebellum South managed their estates progressively, efficiently, and with a political economy that reflected the emerging capitalist values of nineteenth-century America. By fusing economic progress and slave labor, sugar planters revolutionized the means of production and transformed the institution of slavery. Slaveholders and bondspeople redefined the parameters of paternalism and recast the master-slave relationship along a novel path. Louisiana slaves accommodated the machine, holding no torch for Luddism while concurrently shaping the agro-industrial revolution to achieve modest economic independence and relative autonomy within the plantation quarters

"EDGE" OR "EDGELESS" CITIES? URBAN SPATIAL STRUCTURE IN U.S. METROPOLITAN AREAS, 1980 TO 2000

This paper presents a descriptive analysis of spatial trends in six U.S. metropolitan areas. The results show that generalized job dispersion was a more common spatial process than subcentering during the 1980s and 1990s when jobs continued to decentralize from the metropolitan core to the suburbs. Three distinctive patterns of spatial development were found. Job dispersion was predominant in Portland and Philadelphia, whereas the polycentricity of Los Angeles and San Francisco was further reinforced. New York and Boston with large and long-established CBDs were less prone to decentralization. Each metro seems to have developed a unique pattern of decentralization in light of their histories and circumstances, which has limited the growth of commuting times. Copyright Blackwell Publishing, Inc. 2007