Enterobacteriaceae and Aeromonas hydrophila in Minnesota frogs and tadpoles (Rana pipiens).

In 222 Rana pipiens frogs and 34 tadpoles captured in and near Minnesota, Aeromonas hydrophila and 29 species of Enterobacteriaceae, including yersinia enterocolitica and Salmonella arizonae, were isolated from intestines. The prevalence of members of the family Enterobacteriaceae was lowest in frogs captured in early spring and highest in frogs captured in late summer.     

Predictions of protein backbone bond distances and angles from first principles

A procedure is described, based on a spline-function representation of ab initio peptide conformational geometry maps, that allows one to predict backbone bond distances and angles of proteins as functions of the peptide ?(N-C^α)/Ψ(C^α-C′) torsions with an accuracy comparable to that of high-resolution protein crystallography. For example, for the more than 40 residues of crambin, the rms deviation between predicted and crystallographic values of N-C^α-C′ is 1.9° for the 1.5 Å resolution structure and 1.9° for the 0.83 Å resolution structure, compared with angle variations of < 10°. Accurate information on protein backbone geometries is important for establishing dictionaries of flexible geometry functions for use in empirical peptide and protein modeling. © 1995 John Wiley & Sons, Inc.     

Culture of bovine embryos after invitro exposure to Brucellaabortus

Fifty-four day-6 through day-10 (estrus=day 0) embryos were collected nonsurgically from 13 superovulated, brucellosis-free mixed breed cows. Forty-eight excellent and good zona pellucida-intact (ZP-I), three zona pellucida-defective (ZP-D), and three zona pellucida-free (ZP-F) embryos were incubated in media containing $\text{Brucella}$$\text{abortus}$. Subsequently, embryos were washed ten times in groups of one, two, three, or four. Embryos and serial washes were cultured for $\text{B}$. $\text{abortus}$.Brucellae were not isolated from any ZP-I embryo or from any washing beyond the sixth serial wash. Brucellae were not isolated from the three ZP-F embryos but were detected in the eighth wash for one and in the tenth wash for the others. Brucellae were isolated from one of three ZP-D embryos. Results show that ZP-I embryos can be effectively washed free of $\text{B}$. $\text{abortus}$.     

The pericentriolar material in Chinese hamster ovary cells nucleates microtubule formation

The structure and function of the centrosomes from Chinese hamster ovary (CHO) cells were investigated by electron microscopy of negatively stained wholemount preparations of cell lysates. Cells were trypsinized from culture dishes, lysed with Triton X-100, sedimented onto ionized, carbon-coated grids, and negatively stained with phosphotungstate. The centrosomes from both interphase and dividing cells consisted of pairs of centrioles, a fibrous pericentriolar material, and a group of virus-like particles which were characteristic of the CHO cells and which served as markers for the pericentriolar material. Interphase centrosomes anchored up to two dozen microtubules when cells were lysed under conditions which preserved native microtubules. When Colcemid-blocked mitotic cells, initially devoid of microtubules, were allowed to recover for 10 min, microtubules formed at the pericentriolar material, but not at the centrioles. When lysates of Colcemid-blocked cells were incubated in vitro with micotubule protein purified from porcine brain tissue, up to 250 microtubules assembled at the centrosomes, similar to the number of microtubules that would normally form at the centrosome during cell division. A few microtubules could also be assembled in vitro onto the ends of isolated centrioles from which the pericentriolar material had been removed, forming characteristic axoneme- like bundles. In addition, microtubules; were assembled onto fragments of densely staining, fibrous material which was tentatively identified as periocentriolar material by its association of CHO can initiate and anchor microtubules both in vivo and in vitro.     

Prevalence of Yersinia enterocolitica in waters of the lower Chippewa River Basin, Wisconsin.

Water samples collected over a 14-month period from the lower Chippewa River drainage basin in Wisconsin were examined for Yersinia enterocolitica with either MacConkey-Tween 80 agar or Y-M agar (T. N. Saari and G. P. Jansen, Contrib. Microbiol. Immunol. 5:185-196) as the selective medium. A new method of isolation was developed. Of 303 water samples, 8.25% were positive. A seasonal variation was noticed, with winter isolations being most frequent.     

Enterobacteriaceae and Aeromonas hydrophila in Minnesota frogs and tadpoles (Rana pipiens)

In 222 Rana pipiens frogs and 34 tadpoles captured in and near Minnesota, Aeromonas hydrophila and 29 species of Enterobacteriaceae, including yersinia enterocolitica and Salmonella arizonae, were isolated from intestines. The prevalence of members of the family Enterobacteriaceae was lowest in frogs captured in early spring and highest in frogs captured in late summer.     

Targeting of ricin A chain into pea chloroplasts

A chimaeric gene was constructed encoding the pre-sequence of the 33 kDa oxygen-evolving complex protein from wheat (a thylakoid lumen protein) linked to ricin A chain. The fusion protein is efficiently imported by isolated pea chloroplasts and localised partly in the stroma, with the remainder bound to the stromal surface of the thylakoids. The imported protein is fully processed by both the stromal and thylakoidal processing peptidases, indicating that partial or complete translocation across the thylakoid membrane has taken place.     

Two-dimensional NMR and structure determination of salmon calcitonin in methanol

The structure of the 32-residue peptide salmon calcitonin (sCT) in 90% MeOH-10% H2O has been investigated by two-dimensional NMR techniques and molecular modeling. Sequential assignments for nearly all of the 32 spin systems have been obtained, and results indicate that the heptaresidue loop formed by the disulfide bond between Cys-1 and Cys-7 is followed by an alpha-helical segment from Val-8 through Tyr-22. A region of conformational heterogeneity is observed for residues 20-25, resulting from the slow isomerism of the cis and trans forms of Pro-23. The C-terminal segment is found to exist in an extended conformation.     

NMR structural refinement of an extrahelical adenosine tridecamer d(CGCAGAATTCGCG)2 via a hybrid relaxation matrix procedure

Until very recently interproton distances from NOESY experiments have been derived solely from the two-spin approximation method. Unfortunately, even at short mixing times, there is a significant error in many of these distances. A complete relaxation matrix approach employing a matrix eigenvalue/eigenvector solution to the Bloch equations avoids the approximation of the two-spin method. We have calculated the structure of an extrahelical adenosine tridecamer oligodeoxyribonucleotide duplex, d(CGCAGAATTCGCG)2, by an iterative refinement approach using a hybrid relaxation matrix method combined with restrained molecular dynamics calculations. Distances from the 2D NOESY spectra have been calculated from the relaxation rate matrix which has been evaluated from a hybrid NOESY volume matrix comprising elements from the experiment and those calculated from an initial structure. The hybrid matrix derived distances have then been used in a restrained molecular dynamics procedure to obtain a new structure that better approximates the NOESY spectra. The resulting partially refined structure is then used to calculate an improved theoretical NOESY volume matrix which is once again merged with the experimental matrix until refinement is complete. Although the crystal structure of the tridecamer clearly shows the extrahelical adenosine looped out way from the duplex, the NOESY distance restrained hybrid matrix/molecular dynamics structural refinement establishes that the extrahelical adenosine stacks into the duplex.