Search

To study the secular evolution of the activity of Centaur 166P/2001 T4 (Near Earth Asteroid Tracking, NEAT) and its physical properties, we present the results of optical observations of the Centaur taken on 2009 March 29 with the Keck 10-m telescope located atop Mauna Kea, Hawaii. It was still active at r(h) = 11.9 au post-perihelion. An upper limit of the nucleus radius of a(N) < 14.32 km is derived. The colour index is B - R = 1.59 +/- 0.05. The Af rho value is measured to be 288 +/- 19 cm and the corresponding dust production rate is 252 kg s(-1). Finally, a possible mechanism of activity is discussed.

We presentphotometric investigations of three distant active comets, 228P/LINEAR, C/2006 S3 Lowell Observatory Near-Earth-Object Search (LONEOS) and 29P/Schwassmann-Wachmann 1. The data were obtained with the 1-m optical telescope at Lulin Observatory in Taiwan on 2011 February 5 and 6. These comets were observed at heliocentric distances larger than 3 au, all of them appeared to be active. By cometary morphological and photometric studies, the upper limits of the nuclei radii were derived. Also, the surface brightness profiles, Af rho parameters, mass production rates and the coma colours were measured. Finally, we discussed possible driver of activity in comets.

Apolipoprotein B (apoB) is a major protein component of low density and very low density lipoproteins. Because of its large size and heterogeneity, molecular studies of apoB have been difficult, and its structure and regulation remain poorly understood. We now report the identification of human apoB cDNA clones by antibody screening of hepatoma libraries in the expression vector lambda gt11. Both oligo(dT) primed and random primed libraries were constructed and screened with polyclonal antibodies to intact apoB, as well as with antibodies raised against a synthetic peptide based on the limited amino acid sequence available for apoB. The identity of the clones was unambiguously established by comparisons of the cloned cDNA sequences with apoB amino acid sequences. The clones hybridize to an exceptionally large 20 kb mRNA that is present in liver and intestine but not other tissues examined, consistent with the distribution expected from protein biosynthetic studies. The properties of the mRNA have implications for the biogenesis of the multiple apoB molecular weight forms secreted by liver and intestine.