University of Maryland Biotechnology Institute

About: University of Maryland Biotechnology Institute is a based out in . It is known for research contribution in the topics: Gene & Population. The organization has 1565 authors who have published 2458 publications receiving 171434 citations. The organization is also known as: UMBI.

Absence of human herpesvirus 8 DNA sequences in neoplastic Kaposi's sarcoma cell lines.

Abstract: Summary: The recent detection of herpesvirus-like DNA sequences in Kaposi's sarcoma (KS) lesions has led to numerous speculations regarding the role of this new agent in KS pathogenesis. However, recent studies indicate a far wider distribution of such viral sequences, shadowing the potential etiologic role of this agent in KS. In this report we show that malignant KS cell lines do not harbor such viral sequences while B cells, CD14+ and CD34+ cells do, suggesting that if a KS malignancy originates from infection with HHV-8, the virus can be lost and is not necessary for maintenance of the neoplastic state. Alternatively, HHV-8 may be a “passenger” in KS.

Environmental modulation of karlotoxin levels in strains of the cosmopolitan dinoflagellate, Karlodinium veneficum (Dinophyceae).

Abstract: We examined the influence of N or P depletion, alternate N- or P-sources, salinity, and temperature on karlotoxin (KmTx) production in strains of Karlodinium veneficum (D. Ballant.) J. Larsen, an ichthyotoxic dinoflagellate that shows a high degree of variability of toxicity in situ. The six strains examined represented KmTx 1 (CCMP 1974, MD 2) and KmTx 2 (CCMP 2064, CCMP 2283, MBM1) producers, and one strain that did not produce detectable karlotoxin under nutrient-replete growth conditions (MD 5). We hypothesized that growth-limiting conditions would result in higher cell quotas of karlotoxin. KmTx was present in toxic strains during all growth phases and increased in stationary and senescent phase cultures under low N or P, generally 2- to 5-fold but with some observations in the 10- to 15-fold range. No karlotoxin was observed under low-N or low-P conditions in the nontoxic strain MD 5. Nutrient-quality (NO3 , NH4 , urea, and glycerophosphate) did not affect growth rate, but growth on NH4 produced 2- to 3-fold higher cellular toxicity and a 50% higher ratio of KmTx 1-1:KmTx 1-3 in CCMP 1974. CCMP 1974 showed higher cellular toxicity at low salinity (≤5 ppt) and high temperature (25°C). Our results suggested that given the presence of a toxic strain of K. veneficum in situ, the existence of environmental conditions that favor cellular accumulation of karlotoxin is likely a significant factor underlying K. veneficum-related fish kills that require both high cell densities (10(4) · mL(-1) ) and high cellular toxin quotas relative to those generally observed in nutrient-replete cultures.

Sexual Differences in Homing Profiles and Shortening of Homing Duration by Gonadotropin-Releasing Hormone Analog Implantation in Lacustrine Sockeye Salmon (Oncorhynchus nerka) in Lake Shikotsu

Abstract: Adult sockeye salmon (Oncorhynchus nerka) in Lake Shikotsu were captured in September, October and November adjacent to their natal hatchery prior to spawning. They were sampled for hormones, tagged and released in the center of lake. Fish were again sampled at recapture to characterize changes in steroid hormone levels in individual migrants as well as homing percentage and duration in each month. All males returned faster than females early in the breeding season, although a half of the tagged males did not return to the natal site late in the season (November). A high percentage of females always returned, and homing duration shortened late in the season. In males, the shortening of homing duration coincided with an increase in serum testosterone (T) and 11-ketotestosterone levels. In females, the shortening of homing duration corresponded to an elevation of serum T and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) levels, and a drop in serum estradiol-17β levels. Sustained administration of gonadot...

From structure to function: YrbI from Haemophilus influenzae (HI1679) is a phosphatase.

Abstract: The crystal structure of the YrbI protein from Haemophilus influenzae (HI1679) was determined at a 1.67-A resolution. The function of the protein had not been assigned previously, and it is annotated as hypothetical in sequence databases. The protein exhibits the α/β-hydrolase fold (also termed the Rossmann fold) and resembles most closely the fold of the L-2-haloacid dehalogenase (HAD) superfamily. Following this observation, a detailed sequence analysis revealed remote homology to two members of the HAD superfamily, the P-domain of Ca2+ ATPase and phosphoserine phosphatase. The 19-kDa chains of HI1679 form a tetramer both in solution and in the crystalline form. The four monomers are arranged in a ring such that four β-hairpin loops, each inserted after the first β-strand of the core α/β-fold, form an eight-stranded barrel at the center of the assembly. Four active sites are located at the subunit interfaces. Each active site is occupied by a cobalt ion, a metal used for crystallization. The cobalt is octahedrally coordinated to two aspartate side-chains, a backbone oxygen, and three solvent molecules, indicating that the physiological metal may be magnesium. HI1679 hydrolyzes a number of phosphates, including 6-phosphogluconate and phosphotyrosine, suggesting that it functions as a phosphatase in vivo. The physiological substrate is yet to be identified; however the location of the gene on the yrb operon suggests involvement in sugar metabolism. Proteins 2002;46:393–404. © 2002 Wiley-Liss, Inc.