Isolation of Actinobacillus suis from a Canada goose (Branta canadensis)

Blindness from conjunctivitis caused by Actinobacillus suis was found in a Canada goose (Branta canadensis) from a wildlife refuge in Kentucky. Lesions were not observed elsewhere and other body organs were grossly normal. Actinobacillus spp. in birds is rare and this is apparently the first report of conjunctivitis resulting from this infection in waterfowl.     

Moniliformin,deoxynivalenol, 3Acetyldeoxynivalenol and zearalenone — Mycotoxins associated with corn cob fusariosis in Poland

An isolated rat liver was perfused with deoxynivalenol (DON) at a dose of 3 mg in a recirculating perfusion system. To identify glucuronide conjugates equal amounts of bile samples, perfusate and liver homogenates were incubated with and without (control) a β-glucuronidase preparation and analyzed by thin layer chromatography and capillary gas liquid chromatography — chemical ionization mass spectrometry. A total of 40.4% of the administered dose of DON was found to be conjugated with glucuronic acid (perfusate 20.4%, bile 19.2%, liver 0.8%), while only 1.3% of the parent DON (perfusate 1.1%, bile 0.2%) was detected. The cleavage of DON-glucuronide was demonstrated by incubating DON-glucuronide containing bile samples with intestine contents under anaerobic conditions.     

Refinement of the solution structure of the DNA decamer 5'd(CTGGATCCAG)2: combined use of nuclear magnetic resonance and restrained molecular dynamics

The solution structure of the self-complementary DNA decamer 5'd(CTGGATCCAG)2 comprising the specific target site for the restriction endonuclease BamH1 is investigated by using nuclear magnetic resonance sectroscopy and restrained molecular dynamics. With the exception of the H5'/H5" sugar proton resonances, all the nonexchangeable proton resonances are assigned sequentially by using pure-phase absorption two-dimensional nuclear Overhauser enhancement spectroscopy. From the time dependence of the nuclear Overhauser effects a set of 160 approximate interproton distances is determined and used as the basis of a structure refinement employing restrained molecular dynamics in which the interproton distances are incorporated into the total energy function of the system in the form of an effective potential term. Two restrained dynamics simulations are carried out, starting from classical B- and A-DNA [atomic root mean square (rms) difference 5.7 A]. In both cases convergence is achieved to very similar B-type structures with an atomic rms difference of 0.9 A which is comparable to the rms fluctuations of the atoms about their average positions. In addition, the rms difference between the experimental and calculated values of the interproton distances for both average restrained dynamics structures is approximately 0.3 A. These results suggest that the converged restrained molecular dynamics structures represent reasonable approximations of the solution structure. The average restrained dynamics structures exhibit clear sequence-dependent variations of torsion angles and helical parameters. In addition, the structures exhibit a small bend of around 10-20 degrees at the second (TpG) and eighth (CpA) base pair steps. This can be attributed to the positive base roll angles and large base pair slide values at the two Pyr-Pur steps. The central core of the decamer comprising the six-base recognition site for BamH1 (GGATCC), however, is straight.     

Binding of caput epididymal mouse sperm to the zona pellucida

Immature sperm from the caput epididymis are immotile and infertile. It is thought that caput epididymal sperm are infertile due to their immotility, as well as to an inability to bind to the zona pellucida, suggesting the absence of a functional receptor for the zona. However, the sperm receptor for the zona pellucida has been identified previously as the enzyme galactosyltransferase (GalTase) (L. C. Lopez et al. (1985) J. Cell Biol. 101, 1501-1510) and is present on the surface of caput as well as cauda epididymal sperm (N. F. Scully et al., (1987) Dev. Biol. 124, 111-124.). In this paper we examine this apparent conflict and show that immotile caput epididymal sperm are able to bind to the zona pellucida if they are first washed free of caput epididymal secretions, which contain factors that inhibit sperm-zona binding. Consistent with this finding are results that show that caput epididymal fluid is capable of inhibiting the binding of mature, cauda epididymal sperm to the zona pellucida. Caput epididymal fluid contains, among many other components, a soluble GalTase and an alpha-lactalbumin-like protein, both of which are capable of inhibiting mouse sperm-zona binding. Thus, caput epididymal sperm have the appropriate receptor, i.e., GalTase, for the zona pellucida, to which they can bind if removed from the inhibitory factors that mask their zona-binding ability.     

Base pair opening dynamics of a 2-aminopurine substituted Eco RI restriction sequence and its unsubstituted counterpart in oligonucleotides.

Studies of 1H NMR selective saturation recovery were performed to determine the imino proton exchange with solvent water of the base pairs in the Eco RI endonuclease recognition sequence GAATTC, placed at the center of self-complementary decamer and dodecamer oligonucleotides. In one oligonucleotide the innermost adenine was replaced by the fluorescent base analogue 2-aminopurine (2AP). From the measurements at different concentrations of TRIS buffer acting as proton exchange catalyst, base pair lifetimes were evaluated. The results at 25 degrees show that the AT base pairs have lifetimes of the order of a few ms, whereas the surrounding GC base pairs in a dodecamer have lifetimes of about 100 ms. The (2AP)T base pair has a shorter lifetime than the corresponding AT base pair. The temperature dependent optical absorption, and for the 2AP containing oligonucleotide fluorescence, were used to study the single strand-duplex equilibrium of the decamers. The results indicate that NMR and the optical techniques, although applied at very different concentrations, monitor the same conformational transition of the oligonucleotide.     

A selective differential medium for the isolation of Listeria monocytogenes

A new medium has been developed for the isolation of Listeria monocytogenes from clinical specimens with a mixed flora. Almost complete inhibition of unwanted organisms was achieved and recognition of colonies of Listeria spp. was usually possible after 24 h using the aesculin-ferric ammonium citrate indicator system. Compared to McBride agar the new medium was more inhibitory to representative contaminating species in pure culture and more successful in isolating small numbers of L. monocytogenes from artificially seeded clinical specimens.     

Growth and development of winter tick, Dermacentor albipictus, on moose, Alces alces

Moose, Alces alces, were infested with 21,000 or 42,000 larval Dermacentor albipictus at the end of September. Larvae grew rapidly and molted to the nymphal stage 10-22 days after infestation. The nymphal stage lasted approximately 3 mo until mid-January and was characterized by a diapause. The diapause is likely an adaptation to survival in cold climates. Nymphs started engorging in January and adults were seen with increasing abundance from mid-January to March and April. The minimum parasitic period was 175 days. Growth of larvae and nymphs was similar on moose given different numbers of larvae and was generally similar between a moose infested in November and moose infested earlier. Dimensions and stages of development throughout the parasitic phase are given. Game enforcement officers are encouraged to use these data for determination of season of death of moose.     

Comparison of zona cutting and zona drilling as techniques for assisted fertilization in the mouse

Zona cutting and zona drilling of the mouse oocyte significantly increased the fertilization rate (3.8-90%) at low sperm concentrations (less than 200,000/ml) compared with zona-intact controls (0-45%). More oocytes were fertilized after zona drilling. Zona cutting was associated with a low loss of oocytes (less than 1%), no increase in polyspermy and normal development in vitro and in vivo after fertilization. There was a 4% oocyte loss rate after zona drilling, mostly due to extrusion of the oocyte from the zona during the procedure. Hatching of blastocysts occurred about 12 h earlier for zona-drilled than for zona-cut and zona-intact control oocytes. Zona drilling was associated with a higher, but not statistically significant, rate of polyspermy at all sperm concentrations tested. The proportion of zygotes developing to the blastocyst stage was not different between the techniques (zona cut, 77%; zona drilled, 66%; control, 71%). Similarly, no difference was found in the percentage of embryos implanting after blastocyst transfer to the uterine horns of pseudopregnant female mice (zona cut, 67%; zona drilled, 68%; control, 77%). Transmission electron microscopy demonstrated the induced defects in the zona with no damage to the oocyte or oolemma. Parthenogenetic activation was not seen after either of the micromanipulative techniques. Both techniques have promise for application to the human.