Water use by the desert cucurbit Citrullus colocynthis (L.) Schrad.

Summary The rates of water use and leaf surface conductance of Citrullus colocynthis (Cucurbitacea) were evaluated from measurements of the surface temperature and microenvironment of leaves. At desert sites in Saudi Arabia the transpiration rates reached 0.13–0.17 g m^-2 s^-1 and the leaf temperatures were always close to air temperature. Leaf models (dry) placed in the canopy were considerably warmer than the air. To investigate responses over a wider range of conditions, plants were grown in a controlled environment room. It was found that when conditions were made hotter than those that occurred in the desert, the stomatal conductance increased greatly. Transpiration rate attained 0.6 g m^-2 s^-1 and the leaves were up to seven degrees cooler than the air. The results suggest a finely-tuned control mechanism working like a switch when the leaves experience extreme conditions, and enabling the plant to avoid lethal temperatures.     

Lipid composition of adult Foleyella agamae

Full-size image

& Obiamiwe B. A. 1986. Lipid composition of adult Foleyella agamae. International Journal for Parasitology 16: 655–657. The lipid and fatty acid composition of the filarial parasite Foleyella agamae were investigated. Total lipids accounted for 7.05% of the parasite fresh weight. Neutral lipids comprised 56.34% of the total and polar lipids 43.66%. The major lipid classes detected include sterol esters, cholesterol, phosphatidyl choline and phosphatidyl ethanolamine. Fatty acids varying in chain length from 10 carbon atoms through 20 carbon atoms were identified in the total lipid extract. The 18 carbon fatty acids formed the predominant components. The 20 carbon fatty acids were confined to the polar lipds.     

EPR and EXAFS studies of glucose isomerase activation by divalent metals

The interactions of Mn²⁺ and Co²⁺ with glucose isomerases from three microbial sources have been studied using various direct physical methods. Co²⁺ was found to activate each enzyme, although the degree of activation varied significantly for enzymes from different organisms. EPR spectroscopy measurements revealed that dissimilarities in the coordination sphere of enzyme-bound Mn²⁺ accompanied the differences in enzyme activity. Variations in the EPR spectra of a nitroxide spin label coupled to two of the three isomerases, possibly near their active sites, were also observed. In no case was the EPR spectrum influenced by Co²⁺ addition, a result discordant with the hypothesis that Co²⁺ activates the enzyme by inducing a conformational change. The proximal biochemical environment of enzymebound Co²⁺ was also examined using EXAFS spectroscopy. This method showed that glucose causes notable changes in the ligand environment of the enzyme-bound metal, suggesting the formation of an enzyme-metal-substrate bridge complex. The significance of these results relative to possible reaction mechanisms is discussed.     

Enzyme polymorphism in Drosophila melanogaster populations in Iraq

Electrophoretic studies of the degree and pattern of polymorphism at two third-chromosome loci, esterase-6 (Est-6) and phosphoglucomutase (PGM), were carried out in three Drosophila melanogaster populations collected from different localities in Iraq: Mosul, Tuwaitha, and Basrah. The results show that only the Tuwaitha population was polymorphic for both loci; the other two populations were polymorphic for Est-6 and monomorphic for PGM. The allele frequency changes at both loci were followed for 20 generations in an experimental cage derived from the Tuwaitha population; it was found that there is a deviation from Hardy-Weinberg equilibrium at both loci toward the homozygote.     

Isolation of the first trypsin inhibitor from the genusAspergillus

The fungusAspergillus flavipes was grown on a Czapeck sucrose medium; the biomass so obtained was treated with high concentration of sucrose to release intracellular metabolites. Sephadex G-75 chromatography of the latter yielded a pure protein having anti-trypsin activity in vitro.     

A review of the taxonomy and systematics of the pentastomid genus Raillietiella Sambon, 1910 with a description of a new species

Systematic Parasitology - Four previously established Raillietiella spp. are redescribed. Two of these, R. kochi and R. shipleyi from African monitor lizards, cannot be reliably separated, R....     

Isolation and identification of two isomeric trihydroxy octadecenoic acids with prostaglandin E-like activity from onion bulbs (Allium cepa)

Two fractions with prostaglandin E-like activity were isolated from onion (Allium cepa) by using XAD-2 adsorption, silicic acid column chromatography and thin layer chromatography. The fractions were analyzed by gas chromatography/mass spectrometry and were characterized as isomeric mixtures of 9,10,13-trihydroxy-11-octadecenoic and 9,12,13-trihydroxy-10-octadecenoic acid, which are lipoxygenase metabolites of linoleic acid. Bio-assay, for which cascade superfusion was used and the rabbit coeliac and mesenteric arteries and the rat fundus strip were employed as assay organs, was utilized to monitor the bio-active profile throughout the isolation procedures. The activity of 1 microgram of the pharmacologically active fractions T1 and T2 was found to be equivalent to that of respectively 1.33 and 0.63 ng of prostaglandin E2.     

Definition of essential sequences and functional equivalence of elements downstream of the adenovirus E2A and the early simian virus 40 polyadenylation sites.

In addition to the highly conserved AATAAA sequence, there is a requirement for specific sequences downstream of polyadenylic acid [poly(A)] cleavage sites to generate correct mRNA 3' termini. Previous experiments demonstrated that 35 nucleotides downstream of the E2A poly(A) site were sufficient but 20 nucleotides were not. The construction and assay of bidirectional deletion mutants in the adenovirus E2A poly(A) site indicates that there may be redundant multiple sequence elements that affect poly(A) site usage. Sequences between the poly(A) site and 31 nucleotides downstream were not essential for efficient cleavage. Further deletion downstream (3' to +31) abolished efficient cleavage in certain constructions but not all. Between +20 and +38 the sequence T(A/G)TTTTT was duplicated. Function was retained when one copy of the sequence was present, suggesting that this sequence represents an essential element. There may also be additional sequences distal to +43 that can function. To establish common features of poly(A) sites, we also analyzed the early simian virus 40 (SV40) poly(A) site for essential sequences. An SV40 poly(A) site deletion that retained 18 nucleotides downstream of the cleavage site was fully functional while one that retained 5 nucleotides downstream was not, thus defining sequences required for cleavage. Comparison of the SV40 sequences with those from E2A did not reveal significant homologies. Nevertheless, normal cleavage and polyadenylation could be restored at the early SV40 poly(A) site by the addition of downstream sequences from the adenovirus E2A poly(A) site to the SV40 +5 mutant. The same sequences that were required in the E2A site for efficient cleavage also restored activity to the SV40 poly(A) site.     

HPLC analysis of furazolidone in goats given the therapeutic dose

Furazolidone (FZ) was given to Nubian goats at the recommended therapeutic dose of 10 mg/kg body wt, for 5 days. The animals were slaughtered 24 hr after the last dose, and their livers, gluteal muscles, kidneys and hearts analysed for FZ residues by an HPLC method with a detection limit of 0.05 micrograms g-1. The drug was detected in the muscle and liver at concentrations of 0.256 +/- 0.009, 0.101 +/- 0.016 micrograms g-1 tissue, respectively. No detectable concentrations of the drug were found in the kidney and heart.     

Cross reactivity and enzyme sensitivity of immunoaffinity purified Sm/RNP antigens

Immunoaffinity purified Sm/RNP antigens from buffalo and goat liver were studied to determine the role of RNA and proteins towards the antigenicity of Sm and RNP antigens. A more direct approach using enzyme-linked immunosorbent assay on nylon beads has been utilized to look into the problem. The effect of enzyme treatment and the role of RNA and protein fractions in influencing antigenicity have been described. RNA seems to be involved in the maintenance of RNP specific polypeptides in suitable conformation so as to keep them in solution. Removal of RNA leads to insolubilization of RNP specific polypeptides. Antibodies to Sm and RNP antigens have been shown to cross react with poly A containing heterogeneous nuclear ribonucleoprotein with no cross reactivity with thymus RNA or DNA.