Basic protein-specific T-cell lines that induce experimental autoimmune encephalomyelitis in SJL/J mice: comparison with Lewis rat lines

Myelin basic protein (BP)-specific T-cell lines were selected from SJL/J mice using techniques to select similar lines from Lewis rats. SJL/J BP-specific T-cell lines were composed of T cells with the helper/inducer phenotype (Lyt 1.2+, 2.2- and L3T4+) and proliferated in response to both the 1-37 and the 89-169 fragments of guinea pig BP. BP-specific T-cell lines transferred delayed-type hypersensitivity (DTH) responses to BP that persisted for over 60 days. Most recipient animals (32/41) developed acute experimental autoimmune encephalomyelitis (EAE), and most survivors (19/24) developed chronic relapsing EAE. Spinal cords of animals during both the acute and the chronic phases of illness contained plaques of demyelination and infiltrates of lymphocytes and macrophages. These findings differed from those of Lewis rat BP-specific lines which respond to a different region of BP, transfer DTH responses that last less than 12 days, and induce acute EAE in which demyelination does not occur.     

A serum-free system for culturing human placental trophoblasts

Summary We have compared hormone production by early gestation and term human placental trophoblasts cultured in Ham's F10 medium containing 10% fetal bovine serum with that by cells cultured in serum-free HB102 medium. Mean daily production of progesterone on Days 3 to 7 was approximately 25% less by both early gestation and term cells cultured in HB102 as compared to Ham's F10, but production was maintained at a stable level for at least 7 d longer than the cells in Ham's. Estradiol production from 10⁻⁶ M dehydroepiandrosterone by both early gestation and term cells was comparable in both media. Human placental lactogen production on Days 3 to 7 was 40% less by cells cultured in HB102. Human chorionic gonadotropin (hCG) output by early gestation cells was also 50% less in HB102 but term cells in HB102 produced twice as much hCG as those in Ham's F10. 3B-Hydroxysteroid dehydrogenase (3BHSD) activity in early gestation and term cells and 11B-hydroxysteroid dehydrogenase (11BHSD) activity of early gestation cultures was comparable in the two media. 11BHSD activity was decreased in the term cultures, and this decrease was more marked in Ham's than in HB102. Sulfatase and aromatase activities in the early gestation cultures were comparable in both media; sulfatase activity was comparable and aromatase activity only 20% less in the term cells cultured in HB102. These results indicate that serum-free HB102 supports differential function of human trophoblast cells and is useful for studies of placental activity for as long as 14 d in culture.     

The 28 kDa apoprotein of CP 26 in PS II binds copper

Photosystem II (PS II) particles isolated from spinach in the presence of 10 M CuSO₄ contained 1.2 copper/300 Chl that was resistant to EDTA. When CuSO₄ was not added during the isolation, PS II particles contained variable amounts of copper resistant to EDTA (0.1–1.1 copper/300 Chl). No correlation was found between copper content and oxygen evolving capacity of the PS II particles. To identify the copper binding protein, we developed a fractionation procedure which included solubilisation of PS II particles followed by precipitation with polyethylene glycol. A 22-fold purification of copper with respect to protein was achieved for a 28 kDa protein. Partial amino acid sequence of a 13 kDa fragment, obtained after V8 (endo Glu-C) protease treatment, showed identity with CP 26 over a 14 amino acid stretch. EPR measurements on the purified protein suggest oxygen and/or nitrogen as ligands for copper but tend to exclude sulfur. We conclude that the 28 kDa apoprotein of CP 26 from spinach binds one copper per molecule of CP 26. A possible function for this copper protein in the xanthophyll cycle is discussed.Abbreviations CP 26 and CP 29 chlorophyll a/b protein complex 26 and 29 - LHC II light-harvesting chlorophyll a/b protein complex of Photosystem II - SB14 sulfobetaine 14 A preliminary report of these results was presented at the IX Int. Congress on Photosynthesis, Nagoya, Japan, 1992.     

Exercise training improves lusitropy by isoproterenol in papillary muscles from aged rats

Taffet, George E., Lloyd A. Michael, and Charlotte A. Tate.Exercise training improves lusitropy by isoproterenol in papillarymuscles from aged rats. J. Appl.Physiol. 81(4): 1488-1494, 1996.Aging isassociated with a decreased cardiac responsiveness to -adrenergicstimulation. We examined the effect of endurance exercise training ofold Fischer 344 male rats on -adrenergic stimulation of the functionof isolated left ventricular papillary muscle. Three groups wereexamined: sedentary mature (SM; 12-mo old), sedentary old (SO;23-24 mo old), and exercised old (EO; 23-24 mo old) that weretreadmill trained for 4-8 wk. The isometric contractile propertieswere studied at 0.2 Hz and 0.75 mM calcium. Without -adrenergicstimulation, there were no group differences for peak tension, maximumrate of tension development(+dP/dt), or maximum rateof tension dissipation(dP/dt). The time to peak tension was longer (P < 0.05) forboth EO and SO than for SM rats. Half relaxation time(RT_1/2) was prolonged(P < 0.05) for SO compared with SMand EO (which did not differ). The three groups did not differ in the-adrenergic stimulation by isoproterenol of peak tension,dP/dt, time to peak tension, orcontraction duration. The inotropic response(+dP/dt) of SM was greater(P < 0.05) than that in SO or EOrats (which did not differ); however, the lusitropic response(RT_1/2) was lesser(P < 0.05) in SO than in SM or EO rats (which did not differ). Thus exercise training of old rats improved the lusitropic response to isoproterenol without altering theage-associated impairment in inotropic response.

     

Guns and butter: a no cost defense against predation for Chrysomela confluens

Summary Chrysomela confluens produces a salicylaldehyde-based defensive secretion which is very effective against generalist predators and apparently produced at no cost. If no cost defenses are common, then one of the basic assumptions in the plant-herbivore literature, i.e. tradeoffs among defense, reproduction, and growth, must be reconsidered. We examined the effectiveness of this defense by exposing defended larvae and larvae whose secretion had been removed to a generalist predator. Larvae which had their secretions intact were attacked by only 7% of the ants which encountered them, and none of these larvae suffered serious damage. In contrast, those which had been milked of their secretions immediately prior to exposure were attacked in 48% of such encounters, and two-thirds of the larvae were killed. Larvae which had been milked 24 or 72 h before exposure, then allowed to regenerate their defenses, were attacked at rates indistinguishable from larvae that had not been milked. Thus regenerated defenses are just as effective as original defenses. We also tested the hypothesis that the cost of defense production and maintainence would be reflected in reductions in developmental rates and final adult mass and increases in leaf consumption rate. We found that larvae which were milked daily of their secretions manifested no measurable cost of recharging reservoirs. Milked larvae grew and fed at the same rates as their control sibs, and became adults of equal or slightly larger size. The liberation of glucose from salicin, a precursor present in leaves of salicaceous hosts, during the production of salicylaldehyde apparently provides enough of an energetic benefit to offset the cost of maintaining an effective defense. Consistent with this hypothesis, we did not find that milked larvae compensated for increased nutritional or salicin demands by increasing their feeding rates. Although this patterns is familiar to chemical ecologists it is generally unappreciated in the plant-herbivore literature. It is likely that many arthropod herbivore defensive systems come at little or no cost, given the intimacy of association between herbivores and their food plants. Sequestration of host plant defensive chemicals which eliminates the cost of synthesis is common in arthropods. The de novo synthesis of chemical defenses may be less costly than expected if it is integrated into other parts of an insects metabolism. Calculations based on the bond energies or molecular constitution of the compounds will not yield a complete perception of cost. Tests over the life of the herbivore, coupled with an understanding of the herbivore's metabolism, are necessary.     

TBX2 acts as a potent transcriptional silencer of tumour suppressor genes through interaction with the CoREST complex to sustain the proliferation of breast cancers

Chromosome 17q23 amplification occurs in 20% of primary breast tumours and is associated with poor outcome. The TBX2 gene is located on 17q23 and is often over-expressed in this breast tumour subset. TBX2 is an anti-senescence gene, promoting cell growth and survival through repression of Tumour Suppressor Genes (TSGs), such as NDRG1 and CST6. Previously we found that TBX2 cooperates with the PRC2 complex to repress several TSGs, and that PRC2 inhibition restored NDRG1 expression to impede cellular proliferation. Here, we now identify CoREST proteins, LSD1 and ZNF217, as novel interactors of TBX2. Genetic or pharmacological targeting of CoREST emulated TBX2 loss, inducing NDRG1 expression and abolishing breast cancer growth in vitro and in vivo. Furthermore, we uncover that TBX2/CoREST targeting of NDRG1 is achieved by recruitment of TBX2 to the NDRG1 promoter by Sp1, the abolishment of which resulted in NDRG1 upregulation and diminished cancer cell proliferation. Through ChIP-seq we reveal that 30% of TBX2-bound promoters are shared with ZNF217 and identify novel targets repressed by TBX2/CoREST; of these targets a lncRNA, LINC00111, behaves as a negative regulator of cell proliferation. Overall, these data indicate that inhibition of CoREST proteins represents a promising therapeutic intervention for TBX2-addicted breast tumours.