A second method for induction of a transmissible entity in the control of cancer in mice.

Spontaneous tumour-bearing mice of the C3H/St and subline C3HB/St inbred strains received injections of three nucleosides, adenosine, 6-methyl adenosine, and 5-methyl cytidine, prepared in the same molecular concentration as they had occurred in an alcohol-soluble liver extract which in previous work had suppressed tumour growth. Two transmissible entities appear to be present and they show different degrees of effect upon the growth and regression of spontaneous tumours of mammary gland origin (adenocarcinoma). The first transmissible entity (TE) occurred in the lineal descent of mice following injection of the liver extract. The second entity (TE2) appeared following injection of 5-methyl cytidine. TE manifested its maximum effect in suppressing cancer in mice during the 20th generation of a lineal descent following the injection of the original liver extract into a mother of the cancer proband. TE2 appears to be optimal in controlling cancer in the F11 generation of a second lineal descent derived from an original cancer proband of the C3H/St inbred strain injected with 5-methyl cytidine.     

Ileal Loop Fluid Accumulation and Production of Diarrhea in Rabbits by Cell-free Products of Clostridium perfringens

The ability of cell extracts and culture filtrates of various strains of C. perfringens to produce ileal loop fluid accumulation and overt diarrhea in rabbits was tested. Good correlation was obtained in the ability of whole cells and a toxic factor (present in cell extracts and concentrated culture filtrates) to produce both fluid accumulation in ileal loops and diarrhea when injected into the normal ileum of the rabbit. The toxic factor was present in cell-free preparations when cells were grown in a sporulation medium, but not when they were grown in an asporogenic medium. The factor was shown to be heat labile, nondialyzable, and was inactivated by Pronase but not by trypsin, lipase, or amylase. Loss of activity occurred at pH 1.0, 3.0, 5.0, and 12.0.     

Determination of surface immunoglobulin density on frozen-thawed mononuclear cells analyzed by the fluorescence-activated cell sorter

Recent data have demonstrated that differences in sIg density on B lymphocytes distinguish functionally distinct subpopulations of these cells. Other reports suggest that cyropreservation may change the frequency of sIg-bearing lymphocytes. To determine if cryopreservation alters either the frequency of sIg cells or the distribution of sIg density, PBM from normals and patients with CLL and LCL were analyzed using the FACS. Aliquots of Ficoll-Hypaque-separated PBM were controlled-rate frozen (1 °C/min) in 7.5% Me₂SO in RPMI 1640 and thawed in a 37 °C water bath on the same day. Fresh and frozen-thawed PBM aliquots were labeled with fluorescein conjugates of F(ab′) fragments of affinity chromatography-purified anti-Fab or class-specific anti-μ, anti-δ, anti-γ, or anti-α. Histograms of relative cell fluorescence, reflecting sIg density, were prepared for each aliquot with the FACS. The frequency of sIg-bearing PBM labeled with each reagent was not significantly altered by freezing. Likewise, FACS profiles demonstrated that the distribution of sIg density on normal and CLL PBM was unchanged after freezing. However, the fluorescence peak produced by frozen-thawed unlabeled cells was occasionally slightly broader than that of fresh cells, suggesting increased autofluorescence induced by freezing. These data indicate that frozen cell preparations may be utilized for the study of B-lymphocyte subsets as determined by sIg density.     

Grassland birds and rotational-grazing in the northeast: Breeding ecology,survival and management opportunities

We studied long-term (2002–2009) demographics of bobolinks (Dolichonyx oryzivorus) and savannah sparrows (Passerculus sandwichensis) breeding in rotationally grazed systems in the northeastern United States. Both nest success (6–44% bobolink; 7–48% savannah sparrow) and annual productivity (0.43–2.83 bobolink; 0.70–2.35 savannah sparrow) varied annually. Predation (48%) and trampling by cows (32%) accounted for most failed nests. Annual adult apparent survival ranged from 23% to 85% and showed substantial variation by species and sex. Although grazing resulted in substantial loss of vegetative cover, savannah sparrows responded similarly to predation and grazing-induced nest failure (time to renest, distance moved between nests) and generally remained in the same paddock to renest. Minimum paddock size to accommodate one female within this rotation was 70 m × 70 m (0.49 ha), allowing a female to stay within a paddock and move (approx. 50 m) between nesting attempts. To balance pasturing objectives and birds' needs in paddocks first grazed before 25 June, managers in the Northeast should rest that paddock 42–50 days before the second grazing. © 2011 The Wildlife Society.