Migration of peripheral T and B cells into the thymus of aging (NZB × SJL)F1 female mice

Aging NZB × SJL (NS) female mice provide a unique model of thymopathology characterized by the intrathymic accumulation of large numbers of mature T and B cells. The purpose of the present work was to examine the possibility that this phenomenon results from the invasion of the thymus by cells from the periphery. Lymphoid cells labeled with chromium-51 or indium-111 were injected into syngeneic recipients to study their patterns of in vivo migration. Lymph node (LN) or spleen cells were found to localize significantly (1–2% of injected radioactivity) into the thymus of 12-month-old NS females but not into that of young recipients or of old NS males. However, intrathymic localization of injected LN cells was observed in castrated NS males which exhibit the same thymopathology as NS females. Both radiolabeled T and B cells were found to enter the thymus of aged NS females but the latter cells about three times less efficiently than the former. Moreover, while thymocytes from young NS females were unable to recirculate to LN, those of old NS females showed increased LN-seeking capacity and part (1%) of them did migrate back into the thymus of old but not young NS females. In additional cell transfer experiments, the intrathymic migration of B cells into old NS females was further documented by using the antibody response to sheep erythrocytes as a tracer. Taken together, these observations indicate that the thymus of aging NS female mice is permeable to recirculating lymphocytes, suggesting that at least part of the mature T and B cells detected in this thymus, are migrants from the periphery.     

125I] 3-quinuclidinyl 4-iodobenzilate: a high affinity, high specific activity radioligand for the M1 and M2-acetylcholine receptors

We have prepared a radioiodinated ligand which binds with high affinity to the muscarinic acetylcholine receptor (m-AChR). A derivative of 3-quinuclidinyl benzilate, [125I] labeled (R) 1-aza-bicyclo(2.2.2)oct-3-yl (R,S)-alpha-hydroxy-alpha-(4-[125I]iodophenyl)phenyl acetate (4- IQNB ) exhibits an affinity for the m-AChR from corpus striatum higher than that of (R) [3H] QNB. Additionally, [125I] 4- IQNB exhibits receptor selectivity for the M1 receptor since the affinity for the receptor from dog and rat heart is lower than that using dog or rat corpus striatum.     

Analysis of the biological properties of antibodies raised against intact and deglycosylated porcine zonae pellucidae

Zonae pellucidae (ZP) were isolated from 1,500 porcine ovaries and heat solubilized to generate approximately 15 mg ZP glycoprotein. Analysis of this material by isoelectric focusing, one-dimensional electrophoresis, and gas chromatography indicated the presence of a major glycoprotein species that exhibited considerable microheterogeneity with respect to its charge (pI 7.5–3.5) and molecular mass (45–85 kDa) and that contained 39.6% carbohydrate, predominantly N-acetylglucosamine. Chemical deglycosylation of porcine ZP using trifluoromethanesulphonic acid (TFMS) resulted in the production of five discrete protein bands on one-dimensional sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS/PAGE) with molecular masses of 66, 52, 36, 32, and 16 kDa. Antisera raised in rabbits and marmosets to ZP and/or deglycosylated ZP (DGZP) were used in immunoblotting experiments to demonstrate the retention of immunogenicity by DGZP and the cross-reactivity of the antisera with their heterologous antigen. These studies indicated that antisera that were capable of inhibiting the fertility of primates in vivo and the penetration of the human ZP in vitro reacted preferentially with 3 of the 5 products of deglycosylation, with molecular masses of 66, 52, and 36 kDa. Anti-DGZP antibodies were also shown to interact with intact porcine and human ZP and, with the latter, to block the ability of human spermatozoa to both bind to and penetrate this structure.     

Plant biomass and nutrient levels of a tropical macrophyte (Cyperus papyrus L.) receiving domestic wastewater

The aboveground biomass and nutrient content ofCyperus papyrus were determined in a small tropical swamp receiving domestic wastewater. It was found that the biomass (4,955 g.m^–2 dry weight) was the highest ever reported for papyrus. The levels of both nitrogen and phosphorus in the plant organs were very high. The nitrogen concentrations of the various plant organs were 4.8% roots, 8.4% rhizomes, 4.5% scales, 4.8% culms, and 6.2% umbels on dry weight basis. As to phosphorus the concentrations were 0.09% roots, 0.11% rhizomes, 0.09% scales, 0.10% culms, and 0.13% umbels. The high biomass and nutrient contents of the plants may have been caused by the high nutrient levels in the surrounding water. Comparison of the nitrogen to phosphorus ratios in the plants to those in the surrounding water showed that the plants stored very high amounts of nitrogen.     

Binding properties and biological potencies of insulin-like growth factors in L6 myoblasts.

Protein synthesis in rat L6 myoblasts is stimulated and protein breakdown inhibited in a co-ordinate manner by insulin-like growth factors (IGF) or insulin. For both processes, bovine IGF-1 was somewhat more potent than human IGF-1, which was effective at a tenth the concentration of insulin, rat IGF-2 or human IGF-2. A similar order of potency is noted when DNA synthesis or protein accumulation is monitored over a 24 h period, but between 20- and 50-fold higher concentrations of each growth factor are required than those needed to produce effects in the 4 h protein-synthesis or -breakdown measurements. Binding experiments with labelled human or bovine IGF-1 as ligand demonstrated competition at concentrations of IGF-2, especially human IGF-2, lower than that of either IGF-1 preparation. This pattern was much more pronounced when the radioligand was either human IGF-2 or rat IGF-2. Insulin competed 10-15% for the binding of labelled IGF-1, but not at all with labelled IGF-2. Ligand-receptor cross-linking experiments showed that labelled bovine IGF-1 bound approximately equally to the type 1 IGF receptor (Mr 130000 after reduction) and to the type 2 IGF receptor (Mr 270000 after reduction), and that unlabelled IGF-1 competed equally with radioligand binding to both receptors. On the other hand, rat IGF-2 competed more effectively for binding to the type-2 receptor, and insulin competed only for binding to the type-1 receptor. Further cross-linking experiments with rat IGF-2 as radioligand demonstrated binding only to the type-2 receptor and to proteins with Mr values after reduction of 230000 and 200000. This binding was prevented by high rat IGF-2 concentrations, less effectively by bovine IGF-1 and not at all by insulin. The apparently conflicting biological potencies and receptor binding of the different growth factors can be explained if all the biological actions are mediated via the type-1 IGF receptor, rather than through the abundant type-2 receptor.     

Characterization of thermophilicCampylobacter: I. Carbon-substrate utilization tests

The carbon-substrate utlization profile of 234 wild strains of thermophilic campylobacters originating from different animal sources and different part of the world was studied using a microgallery as well as the profile of 25 type strains ofCampylobacter species and reference strains ofCampylobacter-like organisms. Among the 98 substrates tested, succinate, fumarate,d-l-lactate,l-malate, pyruvate,l-glutamate,l-aspartate, andl-serine (with one exception for the last two) were always utilized by the wild strains, and acetate, propionate,d-malate, 2-cetoglutarate, itaconate, citrate, andl-proline by some of the strains. A strong association was found between assimilation ofd-malate and a positive hippurate test.     

Transformation ofBacillus spp.: An examination of the transformation ofBacillus protoplasts by plasmids pUB110 and pHV33

The protoplasting and transformation techniques described by Chang and Cohen [5] have been modified by the inclusion of mutanolysin and these techniques have been used to prepare protoplasts of a number ofBacillus spp. Cells of some, however, remained resistant to cell wall hydrolysis by both mutanolysin and lysozyme. Protoplasts were prepared from sixBacillus species, including a strain ofB. subtilis, and transformed with the plasmid pUB110. Transformation with the shuttle vector pHV33 was, however, less successful and antibiotic-resistant protoplasts, although detected, either failed to regenerate their osmotic stability or rapidly lost their antibiotic resistance.     

Distinction between octachlorostyrene and hexachlorobenzene in their potentials to induce ethoxyphenoxazone deethylase and cause porphyria in rats and mice

The potentials of octachlorostyrene (OCS) and hexachlorobenzene (HCB) to induce liver microsomal ethoxyphenoxazone deethylation (an indicator of induction of 3-methylcholanthrene and beta-naphthoflavone-like cytochrome P-450 monoxygenase activity) and cause porphyria in male C57BL/6 and C57BL/10 mice and female F344 rats were compared. Ethoxyphenoxazone deethylation was induced much more by HCB than by OCS in both of these strains of mice (although neither OCS nor HCB greatly induced deethylation in the DBA/2 strain). In rats ethoxyphenoxazone deethylase was induced 26-fold by HCB but only four-fold by OCS, whereas dealkylation of pentoxyphenoxazone (an indicator of phenobarbital-like induction) increased 43- and 36-fold, respectively. Both chemicals were poor inducers of dealkylation of pentoxyphenoxazone in mice. When fed HCB continuously but not when given OCS, C57BL/6 and C57BL/10 mice (both after pretreatment with iron) and F344 rats developed porphyria with a depression of hepatic uroporphyrinogen decarboxylase activity. The results illustrate that in these species OCS and HCB cannot be considered as equally efficient agents for inducing ethoxyphenoxazone deethylation or causing porphyria. If these effects are mediated through binding to the aromatic hydrocarbon responsiveness (Ah) receptor, HCB would appear to have a much greater affinity than OCS despite the face that neither chemical possesses a structure currently considered to be necessary for efficient binding.     

Water temperature: A factor in the seasonality of two freshwater sponge species,Ephydatia fluviatilis and Spongilla alba

Two freshwater sponge species, Ephvdatia fluviatilis and Spongilla alba, were maintained in a continuous-flow laboratory culture system at several different water temperatures. Experimental results suggest that sponge growth rate is affected by water temperature and that it is affected differently in the two species. The results correlate well with field observations on species abundance at different water temperatures and thereby support the view that water temperature is a factor determining seasonality in these species.     

Crystal structure of Boc-Ala-Aib-Ala-Aib-Aib-methyl ester,a pentapeptide fragment of the channel-forming ionophore suzukacillin

t-Buthyoxycarbonyl-L -alanyl-α-aminiosobutyryl-L -alanyl-α-aminoisobutyryl-α-aminoisobutyric acid methyl ester (t-Boc-L -Ala-Aib-L -Ala-Aib-Aib-OMe), C₂₄H₄₃N₅O₈, an end-protected pentapeptide with a sequence corresponding to the 6th through the 10th residues in suzukacillin, crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 11.671, b = 14.534, c = 17.906 Å and z = 4. The molecule exists as a right-handed 3₁₀-helix with a pitch of 6.026 Å. The helix is stabilized by three 4 → 1 hydrogen bonds with the NH groups of Ala(3), Aib(4), and Aib(5) hydrogen bonding to the carbonyl oxygens of t-Boc, Ala(1), and Aib(2), respectively. The helical molecules arrange themselves in a head-to-tail fashion along the a direction in such a way that the NH groups of Ala(1) and Aib(2) hydrogen bond to the carbonyl oxygens of Aib(4) and Aib(5), respectively, of a translationally related molecule. The helical columns thus formed close-pack nearly hexagonally to form the crystal.