ALBERT

Description: The Abdominal gene is a member of the single homeotic complex of the beetle, Tribolium castaneum. An integrated developmental genetic and molecular analysis shows that Abdominal is homologous to the abdominal-A gene of the bithorax complex of Drosophila. abdominal-A mutant embryos display strong homeotic transformations of the anterior abdomen (parasegments 7-9) to PS6, whereas developmental commitments in the posterior abdomen depend primarily on Abdominal-B. In beetle embryos lacking Abdominal function, parasegments throughout the abdomen are transformed to PS6. This observation demonstrates the general functional significance of parasegmental expression among insects and shows that the control of determinative decisions in the posterior abdomen by homeotic selector genes has undergone considerable evolutionary modification.

Description: The genetic control of embryonic organization is far better understood for the fruit fly Drosophila melanogaster than for any other metazoan. A gene hierarchy acts during oogenesis and embryogenesis to regulate the establishment of segmentation along the anterior-posterior axis, and homeotic selector genes define developmental commitments within each parasegmental unit delineated. One of the most intensively studied Drosophila segmentation genes is fushi tarazu (ftz), a pair-rule gene expressed in stripes that is important for the establishment of the parasegmental boundaries. Although ftz is flanked by homeotic selector genes conserved throughout the metazoa, there is no evidence that it was part of the ancestral homeotic complex, and it has been unclear when the gene arose and acquired a role in segmentation. We show here that the beetle Tribolium castaneum has a ftz homolog located in its Homeotic complex and expressed in a pair-rule fashion, albeit in a register differing from that of the fly gene. These and other observations demonstrate that a ftz gene preexisted the radiation of holometabolous insects and suggest that it has a role in beetle embryogenesis which differs somewhat from that described in flies.

Description: In Drosophila, the establishment of regional commitments along most of the anterior/posterior axis of the developing embryo depends on two clusters of homeotic genes: the Antennapedia complex (ANT-C) and the bithorax complex (BX-C). The red flour beetle has a single complex (HOM-C) representing the homologues of the ANT-C and BX-C in juxtaposition. Beetles trans-heterozygous for two particular HOM-C mutations spontaneously generate a large deficiency, presumably by an exchange within the common region of two overlapping inversions. Genetic and molecular results indicate that this deficiency spans at least the interval between the Deformed and abdominal-A homologues. In deficiency homozygous embryos, all gnathal, thoracic and abdominal segments develop antennal appendages, suggesting that a gene(s) has been deleted that acts to distinguish trunk from head. There is no evidence that beetles have a homologue of the segmentation gene fushi tarazu of similar genomic location and function. On the basis of the genetic tractability, convenient genome size and organization of Tribolium, and its relatively long phylogenetic divergence from Drosophila (〉300 million years), we have integrated developmental genetic and molecular analyses of the HOM-C. We isolated about 70 mutations in the complex representing at least six complementation groups. The homeotic phenotypes of adults and lethal embryos lead us to believe that these beetle genes are homologous with the Drosophila genes indicated in Fig. 1 (see text).

Description: The powerful combination of genetic, developmental and molecular approaches possible with the fruit fly, Drosophila melanogaster, has led to a profound understanding of the genetic control of early developmental events. However, Drosophila is a highly specialized long germ insect, and the mechanisms controlling its early development may not be typical of insects or Arthropods in general. The beetle, Tribolium castaneum, offers a similar opportunity to integrate high resolution genetic analysis with the developmental/molecular approaches currently used in other organisms. Early results document significant differences between insect orders in the functions of genes responsible for establishing developmental commitments.

Description: Amino acid sequence from tryptic peptides of three different bovine corneal keratan sulfate proteoglycan (KSPG) core proteins (designated 37A, 37B, and 25) showed similarities to the sequence of a chicken KSPG core protein lumican. Bovine lumican cDNA was isolated from a bovine corneal expression library by screening with chicken lumican cDNA. The bovine cDNA codes for a 342-amino acid protein, M(r) 38,712, containing amino acid sequences identified in the 37B KSPG core protein. The bovine lumican is 68% identical to chicken lumican, with an 83% identity excluding the N-terminal 40 amino acids. Location of 6 cysteine and 4 consensus N-glycosylation sites in the bovine sequence were identical to those in chicken lumican. Bovine lumican had about 50% identity to bovine fibromodulin and 20% identity to bovine decorin and biglycan. About two-thirds of the lumican protein consists of a series of 10 amino acid leucine-rich repeats that occur in regions of calculated high beta-hydrophobic moment, suggesting that the leucine-rich repeats contribute to beta-sheet formation in these proteins. Sequences obtained from 37A and 25 core proteins were absent in bovine lumican, thus predicting a unique primary structure and separate mRNA for each of the three bovine KSPG core proteins.

Description: A viewgraph presentation of a prototype Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) for atmospheric temperature sounding is shown. The topics include: 1) Overview; 2) Requirements & Error allocations; 3) Design; 4) Problems, and How We Solved Them; and 5) Results

Description: An error budget is presented to meet 1 Kelvin radiometric accuracy in a geostationary atmospheric sounder with 50 km spatial resolution on the earth. The gain and phase errors are weighted by the magnitude of visibility versus antenna separation, and requirements range between approx.0.5% and 0.3 degrees of amplitude and phase, respectively, for the closest spacings at the center of the array, and about 5% and 3 degrees for the majority of the array. The latter requirement is met by our design without any special testing or stabilizations by reference signals. The former is met using an internal noise diode reference and by measuring the detailed antenna patterns on the antenna range. Biases and other additive errors in the raw visibility samples must be below about 2 mK on average, and this requirement is met by a phase shifting scheme applied to the local oscillator distribution. An outline of the data processing is presented, along with the first images from this system.

Description: The Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR) is a new Earth remote sensing instrument concept that has been under development at the Jet Propulsion Laboratory. First conceived in 1998 as a NASA New Millennium Program mission and subsequently developed in 2003-2006 as a proof-of-concept prototype under the NASA Instrument Incubator Program, it is intended to fill a serious gap in our Earth remote sensing capabilities - namely the lack of a microwave atmospheric sounder in geostationary orbit. The importance of such observations have been recognized by the National Academy of Sciences National Research Council, which recently released its report on a 'Decadal Survey' of NASA Earth Science activities1. One of the recommended missions for the next decade is a geostationary microwave sounder. GeoSTAR is well positioned to meet the requirements of such a mission, and because of the substantial investment NASA has already made in GeoSTAR technology development, this concept is fast approaching the necessary maturity for implementation in the next decade. NOAA is also keenly interested in GeoSTAR as a potential payload on its next series of geostationary weather satellites, the GOES-R series. GeoSTAR, with its ability to map out the three-dimensional structure of temperature, water vapor, clouds, precipitation and convective parameters on a continual basis, will significantly enhance our ability to observe hurricanes and other severe storms. In addition, with performance matching that of current and next generation of low-earth-orbiting microwave sounders, GeoSTAR will also provide observations important to the study of the hydrologic cycle, atmospheric processes and climate variability and trends. In particular, with GeoSTAR it will be possible to fully resolve the diurnal cycle. We discuss the GeoSTAR concept and basic design, the performance of the prototype, and a number of science applications that will be possible with GeoSTAR. The work reported on here was performed at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration.