Presence of haemocyte-like cells in coccinellid reflex blood

Abstract.  Contrary to current assumptions, the reflex blood of two-spot ladybirds, Adalia bipunctata , and seven-spot ladybirds, Coccinella septempunctata , contains haemocyte-like cells. Furthermore, DNA can be extracted and amplified from coccinellid reflex blood, confirming the presence of haemocyte-like cells and demonstrating a nondestructive method of DNA extraction.     

Ovomucoid third domains from 100 avian species: isolation, sequences, and hypervariability of enzyme-inhibitor contact residues

Ovomucoids were isolated from egg whites of 100 avian species and subjected to limited proteolysis. From each an intact, connecting peptide extended third domain was isolated and purified. These were entirely sequenced by single, continuous runs in a sequencer. Of the 106 sequences we report (five polymorphisms and chicken from the preceding paper [Kato, I., Schrode, J., Kohr, W. J., & Laskowski, M., Jr. (1986) Biochemistry (preceding paper in this issue)]), 65 are unique. In all cases except ostrich (which has Ser45), the third domains are either partially or fully glycosylated at Asn45. The majority of the third domain preparations we isolated are carbohydrate-free. Alignment of the sequences shows that their structurally important residues are strongly conserved. On the other hand, those residues that are in contact with the enzyme in turkey ovomucoid third domain complex with Streptomyces griseus proteinase B [Read, R., Fujinaga, M., Sielecki, A. R., & James, M. N. G. (1983) Biochemistry 22, 4420-4433] are not conserved but instead are by far the most variable residues in the molecule. These findings suggest that ovomucoid third domains may be an exception to the widely accepted generalization that in protein evolution the functionally important residues are strongly conserved. Complete proof will require better understanding of the physiological function of ovomucoid third domains. This large set of variants differing from each other in the enzyme-inhibitor contact area and augmented by several high-resolution structure determinations is useful for the study of our sequence to reactivity (inhibitory activity) algorithm. It is also useful for the study of several other protein properties. In the connecting peptide fragment most phasianoid birds have the dipeptide Val4-Ser5, which is absent in most other orders. This dipeptide is often present in only 70-95% of the molecules and appears to arise from ambiguous excision at the 5' end of the F intron of ovomucoid. Connecting peptides from the ovomucoids of cracid birds contain the analogous Val4-Asn5 peptide. In laughing kookaburra ovomucoid third domain we found (in 91% of the molecules) Gln5A, which we interpret as arising from ambiguous intron excision at the 3' end of the F intron.     

Evidence for carrier-mediated,energy-dependent uptake of urea in some bacteria

Evidence for the existence of an energy-dependent urea permease was found for Alcaligenes eutrophus H16 and Klebsiella pneumoniae M5a1 by studying uptake of ¹⁴C-urea. Since intracellular urea was metabolized immediately, uptake did not result in formation of an urea pool. Evidence is based on observations that the in vivo urea uptake and in vitro urease activity differ significantly with respect to kinetic parameters, temperature optimum, pH optimum, response towards inhibitors and regulation. The K _m for urea uptake was 15–20 times lower (38 M and 13 M urea for A. eutrophus and K. pneumoniae, respectively) than the K _m of urease for urea (650 M and 280 M urea), the activity optimum for A. eutrophus was at pH 6.0 and 35°C for the uptake and pH 9.0 and 65°C for urease. Uptake but not urease activity in both organisms strongly decreased upon addition of inhibitors of energy metabolism, while in K. pneumoniae, potent inhibitors of urease (thiourea and hydroxyurea) did not affect the uptake process. Significant differences in the uptake rates were observed during growth with different nitrogen sources (ammonia, nitrate, urea) or in the absence of a nitrogen source; this suggested that a carrier is involved which is subject to nitrogen control. Some evidence for the presence of an energy-dependent uptake of urea was also obtained in Pseudomonas aeruginosa DSM 50071 and Providencia rettgeri DSM 1131, but not in Proteus vulgaris DSM 30118 and Bacillus pasteurii DSM 33.Non-standard abbreviations CCCP Carbonylcyanide-m-chlorphenylhydrazone - DCCD dicyclohexylcarbodiimide - DNP 2,4-dinitrophenole     

Polyamines in liver and their influence on chromatin condensation after 17-β estradiol treatment of Atlantic salmon

Atlantic salmon (Salmo salar) were treated with 17- estradiol to induce vitellogenin synthesis in liver. This led to an increase in liver wet weight and total DNA. After incubation with micrococcal nuclease (EC 3.1.31.1) less soluble chromatin was obtained from nuclei of the estradiol treated than the control fish, but active gene regions were solubilized by the nuclease. Thus, in the estradiol treated fish soluble mononucleosomes contained hybridizable vitellogenin gene sequences. As a result of estradiol treatment the content in total liver of putrescine rose 3-fold, that of spermidine 2-fold, while spermine was unchanged. In muscle no significant changes were observed. The regulatory functions of polyamines during gene expression were investigated by binding (¹⁴C)spermine to isolated liver nuclei depleted of endogenous polyamines. The number of binding sites was higher in nuclei of estradiol treated than control fish. (^14C)spermine associated preferentially with micrococcal nuclease insensitive chromatin. Thus, the high content of putrescine and spermidine in liver supported the view of polyamine accumulation in proliferating tissues. The preferential binding to condensed chromatin indicated a stabilizing effect of polyamines on the organization of inactive chromatin structures.Abbreviations MNase micrococcal nuclease - PMSF phenylmethylsulfonylfluoride     

One- and two-dimensional NMR spectral analysis of the consequences of single amino acid replacements in proteins

The traditional approach of using homologous sequences to elucidate the role of specific amino acid residues in protein structure and function becomes more meaningful as the number of differences is minimized, with the limit being alteration of a single residue. For small proteins in solution, NMR spectroscopy offers a means of obtaining detailed information about each residue and its response to a given change in the protein sequence. Extraction of this information has been aided by recent progress in spectrometer technology (higher magnetic fields, more sensitive signal detection, more sophisticated computers) and experimental strategies (new NMR pulse sequences including multiple-quantum and two-dimensional NMR methods). The set of avian ovomucoid third domains, which consists of the third domain proper plus a short leader (connecting peptide) and has a maximum of 56 amino acid residues, offers an attractive system for developing experimental methods for investigating sequence-structure and structure-function relationships in proteins. Our NMR results provide examples of sequence effects on pKa' values, average conformation, and internal motion of amino acid side chains.