Plastid-bearing sea slugs fix CO2 in the light but do not require photosynthesis to survive

Several sacoglossan sea slugs (Plakobranchoidea) feed upon plastids of large unicellular algae. Four species—called long-term retention (LtR) species—are known to sequester ingested plastids within specialized cells of the digestive gland. There, the stolen plastids (kleptoplasts) remain photosynthetically active for several months, during which time LtR species can survive without additional food uptake. Kleptoplast longevity has long been puzzling, because the slugs do not sequester algal nuclei that could support photosystem maintenance. It is widely assumed that the slugs survive starvation by means of kleptoplast photosynthesis, yet direct evidence to support that view is lacking. We show that two LtR plakobranchids, Elysia timida and Plakobranchus ocellatus, incorporate ¹⁴CO₂ into acid-stable products 60- and 64-fold more rapidly in the light than in the dark, respectively. Despite this light-dependent CO₂ fixation ability, light is, surprisingly, not essential for the slugs to survive starvation. LtR animals survived several months of starvation (i) in complete darkness and (ii) in the light in the presence of the photosynthesis inhibitor monolinuron, all while not losing weight faster than the control animals. Contrary to current views, sacoglossan kleptoplasts seem to be slowly digested food reserves, not a source of solar power.     

NaCl and Na2SO4 alter responses of jack pine (Pinus banksiana) seedlings to boron

Using sand culture, we examined the responses of 6-month-old jack pine (Pinus banksiana Lamb.) seedlings to boron and salinity (sodium chloride and sodium sulfate) treatments. During 4 weeks of treatments, 60 mM NaCl and 60 mM Na₂SO₄ significantly decreased survival, new shoot length, number of new roots, shoot to root dry weight ratio and transpiration rates. When applied in absence of the salts, B had little effect on the measured variables. However, when applied together with salts, B decreased seedling survival, increased needle injury and altered tissue elemental concentrations in jack pine seedlings. In 2 mM B treatment, B concentration was higher in the shoots than in the roots. However, when 2 mM B was present in NaCl and Na₂SO₄ treatments, shoot boron concentration declined and greater proportion of B accumulated in the roots. This shift corresponded to a decline in transpiration rates. In plants treated with NaCl, Na accumulated primarily in the shoots, while in Na₂SO₄-treated plants Na accumulated mostly in the roots. Based on the electrolyte leakage and needle necrosis data, Cl^– appears to be the major factor contributing to seedling injury and B aggravates the injurious effects of NaCl. We suggest that Cl^– may contribute to Na and B toxicity in jack pine by altering cell membrane permeability leading to increased Na concentration in the shoots.     

Effects of NaCl, Na2SO4, and mannitol on storage lipid mobilization in the cotyledons and roots of purple alfalfa seedlings

The effects of NaCl, Na₂SO₄, and mannitol on mobilization of storage lipids in the cotyledon mesophyll and root meristem cells during the germination of purple alfalfa (Medicago sativa L.) seeds were studied using the transmission electron microscopy technique. The ultrastructural analysis showed that the number and shape of specific organelles, oleosomes, depended on the osmotic effects of a salt used. In control seedlings grown on distilled water, lipid mobilization in roots terminated by the 4th day, and in cotyledons, only by the 8th day. The disruptions in the storage lipid mobilization in the treated seedlings were specific and depended on the stress agent used, the osmotic pressure induced by this agent, as well as on the tissue type. The presence of a great number of oleosomes in the cytoplasm of cells subjected to osmotic stress, in contrast to the control ones, demonstrated the inhibition of mobilization processes. All concentrations of Na₂SO₄ and mannitol suppressed lipid mobilization in the cotyledons and roots. At the same time, NaCl markedly suppressed this process in the root cells only at a higher osmotic pressure of the solution. The results obtained suggest that the cytological analysis of cotyledon storage-lipid mobilization can tentatively assess the resistance of dicotyledonous plants to abiotic stresses.     

Salt resistance of chickpea genotypes in solutions salinized with NaCl or Na2SO4

Summary To assess the potential for developing a salt resistant cultivar of chickpea (Cicer arietinum L.) 160 genotypes were screened for percent survival after 9 weeks in greenhouse solution cultures, with 50 mM NaCl or 25 mM Na₂SO₄. All plants grew well in the sulfate treatment but only cv. L-550 survived the chloride treatment. Salt damage appeared and developed slowly. To check these apparent effects of cultivar and kind of anion, three genotypes including cv. L-550 were then grown in solutions with isoosmotic NaCl or Na₂SO₄ at three levels (−0.044, −0.088, and −0.132 MPa), and in a separate experiment cv. L-550 was grown with NaCl and Na₂SO₄ at four levels: 10, 20, 30 and 50 mM Na. Salt composition affected shoot weight less than salt level or cultivar did. Shoot dry weight was only slightly less in chloride treatments than in isoosmotic sulfate, and for the least sensitive cultivar (L-550) this held only at the highest salt level, corresponding to that in the screening trial. Further, sensitivity to sulfate and to chloride was equal when sodium concentrations in shoots were equal, regardless of anion compositions of media. Shoot Na concentration was a useful negative indicator of growth under salt stress regardles of cultivar, and may be a useful tolerance indicator also for other species that neither accumulate nor efficiently exclude Na.     

Effects of NaCl and Na2SO4 on red-osier dogwood (Cornus stolonifera Michx) seedlings

Sodium chloride and sodium sulfate are commonly present in extraction tailings waters produced as a result of surface mining and affect plants on reclaimed areas. Red-osier dogwood (Cornus stolonifera Michx) seedlings were demonstrated to be relatively resistant to these high salinity oil sands tailings waters. The objectives of this study were to compare the effects of Na₂SO₄ and NaCl, on growth, tissue ion content, water relations and gas exchange in red-osier dogwood (Cornus stolonifera Michx) seedlings. In the present study, red-osier dogwood seedlings were grown in aerated half-strength modified Hoagland's mineral solution containing 0, 25, 50 or 100 mM of NaCl or Na₂SO₄. After four weeks of treatment, plant dry weights decreased and the amount of Na⁺ in plant tissues increased with increasing salt concentration. Na⁺ tissue content was higher in plants treated with NaCl than Na₂SO₄ and it was greater in roots than shoots. However, Cl^– concentration in the NaCl treated plants was higher in shoots than in roots. The decrease in stomatal conductance and photosynthetic rates observed in presence of salts is likely to contribute to the growth reduction. Our results suggest that red-osier dogwood is able to control the transport of Na⁺ from roots to shoots when external concentrations are 50 mM or less.     

Current knowledge about Na2SO4 effects on plants: what is different in comparison to NaCl?

Journal of Plant Research - In some areas of the world, high levels of sodium sulfate (Na2SO4) are found in the soil together with sodium chloride (NaCl). However, most studies on salinity are...     

In vitro selection and characterization of a callus line ofVigna radiata resistant to NaCl,KCl and Na2SO4

A salt mixture resistant (SMR) cell line ofVigna radiata (L.) Wilczek was isolated by selection on agar solidified PC-L2 medium supplemented with NaCl, KCl and Na₂SO₄ (8∶1∶1) equimolar to 300 mol m^?3 NaCl, a concentration inhibitory to the wild-type non-selected cells (salt mixture sensitive, SMS). This line retained its resistance after subculture for 3 passages (3 months) on normal medium. The SMR line grew significantly better than SMS line at all the levels of salts, though less in saline medium than the SMR on normal medium. The growth of SMR line was significantly higher than that of SMS line under KCl stress. However, both the lines responded similarly to Na₂SO₄ at a concentration higher than 100 mol m^?3. The SMR line was found to be more sensitive to NaCl than SMS line. The SMR line under salt mixture stress maintained lower levels of Na⁺ and higher levels of K⁺ than SMS line. The SMR line failed to regenerate shoots, although rhizogenesis was observed on PC-L2 medium containing salt mixture (300 mol m^?3).     

Physiological effects of Na2SO4 and NaCl on callus cultures of Brassica campestris (Chinese cabbage)

Hypocotyl-derived callus cultures of Brassica campestris L. ssp. pekinensis cv. Kim-jung (Chinese cabbage) were grown on Murashige and Skoog medium containing no additional salt, NaCl or Na₂SO₄. Na₂SO₄ was more than twice as inhibitory in comparison to the same concentration of NaCl when growth and fresh:dry weight ratios of established callus were measured. Levels of protein, starch, sucrose and α-amino nitrogen were not significantly altered in salt-grown callus. Concentrations of reducing sugars and chlorophyll were 2–3 times greater in callus grown on either salt. Proline concentration increased 15–20 fold on the highest levels of salt. Final concentrations (reached in 20–24 days) were closely correlated to the initial Na⁺ concentration of the medium, regardless of salt type. The osmotic potential in callus transferred to NaCl or Na₂SO₄ reached a maximum negative value after 16 days. For both salts, subsequent increases were correlated to increases in fresh:dry weight and growth. On both salts, turgor remained relatively constant (0. 6–0.75 MPa). Changes in Na⁺, K⁺, Mg²⁺ and Ca²⁺ content were correlated to initial Na⁺ concentration in the medium, not salt type. Accumulation of Na⁺ was accompanied by loss of K⁺ and Mg²⁺. Six to seven times less sulfate was measured in callus grown on Na₂SO₄ than chloride in callus grown on similar concentrations of NaCl.     

Growth responses and ion accumulation in the halophytic legume Prosopis strombulifera are determined by Na2SO4 and NaCl

Halophytes are potential gene sources for genetic manipulation of economically important crop species. This study addresses the physiological responses of a widespread halophyte, Prosopis strombulifera (Lam.) Benth to salinity. We hypothesised that increasing concentrations of the two major salts present in soils of central Argentina (Na₂SO₄, NaCl, or their iso‐osmotic mixture) would produce distinct physiological responses. We used hydroponically grown P. strombulifera to test this hypothesis, analysing growth parameters, water relations, photosynthetic pigments, cations and anions. These plants showed a halophytic response to NaCl, but strong general inhibition of growth in response to iso‐osmotic solutions containing Na₂SO₄. The explanation for the adaptive success of P. strombulifera in high NaCl conditions seems to be related to a delicate balance between Na ⁺ accumulation (and its use for osmotic adjustment) and efficient compartmentalisation in vacuoles, the ability of the whole plant to ensure sufficient K⁺ supply by maintaining high K ⁺ /Na ⁺ discrimination, and maintenance of normal Ca^{2 +} levels in leaves. The three salt treatments had different effects on the accumulation of ions. Findings in bi‐saline‐treated plants were of particular interest, where most of the physiological parameters studied showed partial alleviation of SO₄^2?‐induced toxicity by Cl^?. Thus, discussions on physiological responses to salinity could be further expanded in a way that more closely mimics natural salt environments.     

Effects of NaCl and Na2CO3 stresses on photosynthetic ability of Chlamydomonas reinhardtii

Chloride and carbonate salts are the main salts causing salinization and widely exist in aquatic environment, so algae may suffer from salinization stress for high water evaporation. In this study, in order to investigate and compare the toxic effects of the two salts on algal photosynthesis, we used NaCl and Na₂CO₃ to stress Chlamydomonas reinhardtii. Under the two salt stresses, the content of O ₂ ^?· and H₂O₂ in the cells was increased significantly, and it was much higher in Na₂CO₃ treatment than in NaCl treatment at the same Na⁺ concentration. The absorbance spectra and 4^th derivative spectra of photosynthetic pigments were declined under 300 mM NaCl and 25 mM Na₂CO₃ stresses, and remarkably changed under 50 mM and 100 mM Na₂CO₃ stresses. When the cells stressed by the two salts, the maximum quantum yield (Fv/Fm), electron transport rate (ETR) and photochemical quenching (qP) were reduced markedly, but the nonphotochemical dissipation (NPQ) was increased markedly. At the same Na⁺ concentration, Na₂CO₃ stress had stronger toxic effects on photosynthetic ability than NaCl stress.     

Differential sensitivity of stomatal and non-stomatal components to NaCl or Na2SO4 salinity in horsegram, Macrotyloma uniflorum (Lam.)

14CO2 assimilation rate (P), leaf diffusive conductance (gs), photosynthetic electron flow, and activities of enzymes of Calvin cycle were studied in a horsegram [Macrotyloma uniflorum (Lam.)] in response to salinity induced by NaCl or Na2SO4. A significant reduction in P and gs by both salt treatments was registered. Na2SO4 caused a greater reduction in gs than the NaCl salinity. Studies with isolated chloroplasts confirmed a greater sensitivity to NaCl than to Na2SO4. Salinity inhibited the photosynthetic electron transport. The activity of ribulose-1,5-bisphosphate carboxylase (E.C.4.1.1.39) was under salinity inhibited more than the activities of other three enzymes of the Calvin cycle, ribulose-5-phosphate kinase (E.C.2.7.1.19), ribose-5-phosphate isomerase (E.C.5.3.16), and NADP-glyceraldehyde-3-phosphate dehydrogenase (E.C.1.2.13). These inhibitions lead to a reduced capacity for ribulose-1,5-bisphosphate regeneration. Isolated chloroplasts extracted from salt stressed plants and supplemented with the substrates of Calvin cycle could elevate P, but the P was always lower than in the controls. Decreased P in horsegram exposed to high salinity can be attributed to both stomatal and non-stomatal components, however, the sensitivity to the salt source, NaCl or Na2SO4, was different.     

Gas exchange and growth responses of ectomycorrhizal Picea mariana, Picea glauca, and Pinus banksiana seedlings to NaCl and Na2SO4

Abstract: Black spruce (Picea mariana), white spruce (Picea glauca), and jack pine (Pinus banksiana) seedlings were inoculated with Hebeloma crustuliniforme or Laccaria bicolor and subjected to NaCl and Na₂SO₄ treatments. The effects of ectomycorrhizas on salt uptake, growth, gas exchange, and needle necrosis varied depending on the tree and fungal species. In jack pine seedlings, ectomycorrhizal (ECM) fungi reduced shoot and root dry weights and in the ECM white spruce, there was a small increase in dry weights. Sodium chloride treatment reduced net photosynthesis and transpiration rates in the three studied tree species. However, NaCl-treated black spruce and jack pine colonized by H. crustuliniforme maintained relatively high photosynthetic and transpiration rates and needle necrosis of NaCl-treated black spruce seedlings was reduced by the ECM fungi. Higher concentrations of Na+ were found in shoots compared with roots of the three examined conifer species. ECM fungi reduced the concentrations of Na+ mainly in the shoots and this reduction was greater in plants treated with NaCl compared with Na₂SO₄. Shoots contained generally higher concentrations of Cl^- compared with roots. In the NaCl-treated black spruce and white spruce, both ECM species significantly reduced Cl^- concentrations. Our results point to overall greater phytotoxicity of NaCl compared with Na₂SO₄ and support our earlier findings which demonstrated beneficial effects of ECM fungi for woody plants exposed to NaCl stress.     

Ethylene improves Arabidopsis salt tolerance mainly via retaining K+ in shoots and roots rather than decreasing tissue Na+ content

Ethylene has been reported to play an essential role in the response of Arabidopsis to salinity and K⁺ deficiency. It was proposed that plant's ability to maintain potassium (K⁺) and minimize sodium (Na⁺) in tissues of salinity plants is critical for salt tolerance (ST). It is still unclear how ethylene modulates plant ion homeostasis under saline occasions. We employed Arabidopsis wild type (Col-0), ethylene insensitive mutants (ein2-5 and ein3-1) and constitutive triple response mutant (ctr1-1) plants to compare their phenotypic and physiological responses to salinity. Ethephon applied to plants could convert quickly to ethylene and here was applied exogenously to Col-0 seedlings to validate ethylene role in salt response. We showed that ethylene insensitivity in ein2-5 or ein3-1 plants increased Arabidopsis salt sensitivity than in Col-0. However, the salinity-induced adverse effects on Chlorophyll a/b, photosystem II function (Fv/Fm) and redox state were largely amended in the ctr1-1 than in Col-0 plants with the severe salinity. The compatible solute sucrose and antioxidant system were also up-regulated to improve ST in ctr1-1 plants. The ethephon obviously alleviated the salinity-induced restriction in root length. The subsequent analysis on the Na⁺ and K⁺ homeostasis found that ethylene could help plant retain higher shoot or root K⁺ nutrition in the short- or long-term salt-stressed plants. However, the ethylene did not significantly alter sodium buildup and water relation in the salt-stressed plants. Our observations confirmed the key role of ethylene in improved plant ST and highlighted the ethylene ability to retain K⁺, rather than decreasing Na⁺, in shoots and roots to improve Arabidopsis ST.     

Hypotension and bradycardia during caloric restriction in mice are independent of salt balance and do not require ANP receptor

We hypothesized that caloric restriction (CR)-induced hypotension would correlate with increased sodium excretion through an atrial natriuretic peptide (ANP)-dependent mechanism. To test this hypothesis, the cardiovascular parameters of c57/Bl mice were measured with radiotelemetry while urine was collected. The 23-h mean blood pressure (BP) dropped from 108.6 +/- 1.8 to 92.7 +/- 2.4 mmHg, and 23-h heart rate dropped from 624 +/- 5 to 426 +/- 13 beats/min over 7 days of CR at 29 degrees C. Contrary to our hypothesis, urine sodium excretion decreased by 55% by day 7 of CR. Consistent with decreased sodium excretion was the drop in plasma ANP (from 82.4 +/- 4.3 to 68.0 +/- 5.8 pg/ml). To explore the possibility that CR lowers BP through an ANP receptor-dependent mechanism that is independent of its effect on sodium retention, we measured the cardiovascular parameters of mice deficient in the ANP receptor (NPR1(-/-)) or the ANP clearance receptor (NPR3(-/-)). Mean BP fell from 117.1 +/- 3.9 to 108.0 +/- 4.7 mmHg in the NPR1(-/-) mice and from 87.0 +/- 2.4 to 78.4 +/- 1.7 mmHg in the NPR3(-/-) mice during CR. These data indicate that the hypotension induced by CR does not depend on increased sodium excretion. Rather, it appears that the mouse responds to the low BP induced by CR with an increase in sodium reabsorption. Furthermore, circulating ANP levels and data from NPR1(-/-) and NPR3(-/-) mice suggest that the ANP pathway may not be involved in the cardiovascular response to CR.     

Effects of NaCl and Na2SO4 on Water Relations ofPlantago maritima (L.) andPlantago lanceolata (L.)

Transpiration and water absorption rates, stomatal and cuticular resistances to water vapour diffusion, were measured onPlantago maritima (halophyte) andPlantago lanceolata (glycophyte) grown in the presence of NaCl or Na₂SO₄. Water absorption was reduced in the presence of Na₂SO₄ and transpiration rate was increased when NaCl was added to the nutrient solution. The glycophyte daily water balance was more disturbed than that of the halophyte in the presence of Na₂SO₄.     

NaCl、Na_2SO_4和Na_2CO_3胁迫对小麦叶片自由基含量及质膜透性的比较研究

分别用浓度为２５ｍｍｏｌ／Ｌ、５０ｍｍｏｌ／Ｌ、１００ｍｍｏｌ／Ｌ和２００ｍｍｏｌ／Ｌ的ＮａＣｌ、Ｎａ２ＳＯ４和Ｎａ２ＣＯ３的营养液培养小麦４ｄ,较之不含盐的营养液,其自由基含量上升,产生速率增加,叶片质膜透性增加。不同盐的影响也不同,在低浓度时,ＮａＣｌ的影响大于Ｎａ２ＳＯ４,高浓度时,ＮａＣｌ影响小于Ｎａ２ＳＯ４,Ｎａ２ＣＯ３的影响最为显著。实验结果也表现出小麦叶片自由基含量和质膜透性呈现较好的相关性。因此可认为,盐胁迫促使自由基含量增加,自由基通过过氧化作用影响质膜透性,从而影响植物的生长。     

Arbuscular mycorrhizal inoculation improves growth and antioxidative response of Jatropha curcas (L.) under Na2SO4 salt stress

This study investigated the effect of arbuscular mycorrhizal (AM) fungal consortia on growth, photosynthetic pigments, solutes concentration (e.g., sugars and proline), and antioxidant responses at different levels of Na₂SO₄ stress (0–0.5%, w:w) in potted culture of Jatropha. Results showed that increasing salt levels caused a significant reduction in survival (%), growth parameters, leaf relative water content (LRWC) (%), and chlorophyll content with an increase in electrolyte leakage (%) and lipid peroxidation of membranes of Jatropha. AM inoculation improved biomass yields as well as other physiological parameters (LRWC (%), chlorophyll, proline, and soluble sugar) of salt-stressed Jatropha over noninoculated plants. Tolerance index of Jatropha was higher with AM fungi than without at all salt levels; however, a decline in its value was recorded with increased salinity levels. AM inoculation also enhanced the activities of antioxidant enzymes (e.g., superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione reductase) and decreased oxidative damage to lipids. In conclusion, results indicate that AM inoculation was capable of alleviating the damage caused by salinity stress on Jatropha plants by reducing lipid peroxidation of membrane and membrane permeability and increasing the accumulation of solutes and antioxidant enzyme activity.     

The tumor-modulatory effects of Caspase-2 and Pidd1 do not require the scaffold protein Raidd

The receptor-interacting protein-associated ICH-1/CED-3 homologous protein with a death domain (RAIDD/CRADD) functions as a dual adaptor and is a constituent of different multi-protein complexes implicated in the regulation of inflammation and cell death. Within the PIDDosome complex, RAIDD connects the cell death-related protease, Caspase-2, with the p53-induced protein with a death domain 1 (PIDD1). As such, RAIDD has been implicated in DNA-damage-induced apoptosis as well as in tumorigenesis. As loss of Caspase-2 leads to an acceleration of tumor onset in the Eμ-Myc mouse lymphoma model, whereas loss of Pidd1 actually delays onset of this disease, we set out to interrogate the role of Raidd in cancer in more detail. Our data obtained analyzing Eμ-Myc/Raidd^−/− mice indicate that Raidd is unable to protect from c-Myc-driven lymphomagenesis. Similarly, we failed to observe a modulatory effect of Raidd deficiency on DNA-damage-driven cancer. The role of Caspase-2 as a tumor suppressor and that of Pidd1 as a tumor promoter can therefore be uncoupled from their ability to interact with the Raidd scaffold, pointing toward the existence of alternative signaling modules engaging these two proteins in this context.A number of mechanisms have evolved to trace and remove potentially dangerous cells. Deregulation of the induction of apoptosis upon oncogenic stress, for example, can facilitate the accumulation of cells prone to undergo malignant transformation. Cell death by apoptosis depends on the cascade-like activation of proteases of the Caspase family.¹ Among these, the evolutionarily most conserved protease, Caspase-2, turns out to be a potent tumor suppressor in mice^{2, 3, 4, 5, 6, 7} and correlative expression data support a conserved role in human cancer.^{8, 9, 10, 11, 12, 13}Early studies suggested that Caspase-2 interacts with other proteins for its activation (e.g., after genotoxic stress), but the protease seems also able to auto-activate cell death on its own when present in sufficiently high concentration.^{14, 15, 16, 17, 18} The most prominent Caspase-2-containing protein complex was dubbed the ‘PIDDosome'' and described to contain the p53-induced protein with a death domain (PIDD1) and receptor-interacting protein-associated ICH-1/CED-3 homologous protein with a death domain (RAIDD, also known as CRADD).¹⁹ Although the molecular details of the pro-apoptotic potential of Caspase-2 are still discussed and alternative roles in the DNA-damage response, cell cycle arrest or sensor of metabolic stress are mechanistically poorly understood, Caspase-2 clearly limits tumorigenesis in different settings. These include aberrant expression of c-Myc in B cells^{3, 4} or deletion of the DNA-damage response regulator, ataxia telangiectasia mutated kinase (ATM), both driving lymphomagenesis⁶ as well as overexpression of the Her2/ErbB2 oncogene in breast⁵ or that of mutated KRAS in the lung epithelium, driving carcinoma formation.⁷ One of these studies, addressing also the role of Pidd1 in c-Myc-driven lymphomagenesis, revealed an unexpected oncogenic role for Pidd1, thereby questioning the physiological relevance of the PIDDosome complex in Caspase-2-mediated cell death and tumor suppression.^{4, 20} However, the exact role of the scaffold protein Raidd within these processes remains unaddressed so far.Raidd, a bipartite adapter containing a death domain (DD) and a caspase-recruitment domain (CARD) was first described to bind to the DD-containing kinase RIPK1 and the C. elegans caspase CED-3,²¹ supporting a role in cell death initiation. Subsequently, the interaction of Caspase-2 and Raidd was biochemically proven²² and proposed to be required for Caspase-2 autoprocessing preceding its activation.¹⁹ More recent studies propose an anti-inflammatory role for Raidd through suppression of nuclear factor kappa-light-chain enhancer (NF-κB) activation and cytokine production upon T-cell receptor stimulation by negatively interfering with the Carma1/Malt1/Bcl-10 signaling complex.^{23, 24}First evidence for a potential role of RAIDD in human cancer was discovered in a biochemical screen using mantle cell lymphomas, which detected a downregulation of RAIDD by microarray analysis,¹⁰ whereas others reported on RAIDD-linked multidrug resistance in osteosarcoma cells.²⁵ Furthermore, tumor cell apoptosis induced by inhibitors of histone de-acetylases in treatment-resistant adult T-cell leukemia lines reportedly required Caspase-2 and Raidd.²⁶ It is also reported that the Caspase-2/Raidd axis is necessary after ER stress, for example, in the course of infection with the oncolytic maraba virus.²⁷Taken together, these studies support a role for RAIDD in drug-induced cancer cell death as well as in tumor suppression, most likely linked to its role as a direct activator of Caspase-2. Alternatively, RAIDD may negatively interfere with PIDD- or BCL10-regulated NF-κB signaling^{23, 24, 28} and thereby suppress pro-tumorigenic inflammation. To address the role of Raidd in tumorigenesis in more detail, we exploited different mouse models where we induced thymic lymphomas by γ-irradiation, fibrosarcomas by 3-methylcholanthrene (3-MC) injection or B-cell lymphomas by aberrant expression of the c-Myc proto-oncogene. Our results suggest that Raidd is not a suppressor of tumors in the mouse models tested.     

Calcium uptake and Ca2+-ATPase activity in goat spermatozoa membrane vesicles do not require Mg2+

Microsomal membrane vesicles isolated from goat spermatozoa contain Ca²⁺-ATPase, and exhibit Ca²⁺ transport activities that do not require exogenous Mg²⁺ .The enzyme activity is inhibited by calcium-channel inhibitors,e.g. verapamil and diltiazem, like the well known Ca²⁺ , Mg²⁺-ATPase. The uptake of calcium is ATP (energy)-dependent and the accumulated Ca²⁺ can be completely released by the Ca²⁺ ionophore A23187, suggesting that a significant fraction of the vesicles are oriented inside out     

Thermotolerant guard cell protoplasts of tree tobacco do not require exogenous hormones to survive in culture and are blocked from reentering the cell cycle at the G1-to-S transition

When guard cell protoplasts (GCPs) of tree tobacco [Nicotiana glauca (Graham)] are cultured at 32 degrees C with an auxin (1-napthaleneacetic acid) and a cytokinin (6-benzylaminopurine), they reenter the cell cycle, dedifferentiate, and divide. GCPs cultured similarly but at 38 degrees C and with 0.1 micro M +/- -cis,trans-abscisic acid (ABA) remain differentiated. GCPs cultured at 38 degrees C without ABA dedifferentiate partially but do not divide. Cell survival after 1 week is 70% to 80% under all of these conditions. In this study, we show that GCPs cultured for 12 to 24 h at 38 degrees C accumulate heat shock protein 70 and develop a thermotolerance that, upon transfer of cells to 32 degrees C, enhances cell survival but inhibits cell cycle reentry, dedifferentiation, and division. GCPs dedifferentiating at 32 degrees C require both 1-napthaleneacetic acid and 6-benzylaminopurine to survive, but thermotolerant GCPs cultured at 38 degrees C +/- ABA do not require either hormone for survival. Pulse-labeling experiments using 5-bromo-2-deoxyuridine indicate that culture at 38 degrees C +/- ABA prevents dedifferentiation of GCPs by blocking cell cycle reentry at G1/S. Cell cycle reentry at 32 degrees C is accompanied by loss of a 41-kD polypeptide that cross-reacts with antibodies to rat (Rattus norvegicus) extracellular signal-regulated kinase 1; thermotolerant GCPs retain this polypeptide. A number of polypeptides unique to thermotolerant cells have been uncovered by Boolean analysis of two-dimensional gels and are targets for further analysis. GCPs of tree tobacco can be isolated in sufficient numbers and with the purity required to study plant cell thermotolerance and its relationship to plant cell survival, growth, dedifferentiation, and division in vitro.