Glycolate oxidase isoforms are distributed between the bundle sheath and mesophyll tissues of maize leaves

Glycolate oxidase (EC 1.1.3.15) activity was detected both in the bundle sheath (79%) and mesophyll (21%) tissues of maize leaves. Three peaks of glycolate oxidase activity were separated from maize leaves by the linear KCl gradient elution from the DEAE-Toyopearl column. The first peak corresponded to the glycolate oxidase isoenzyme located in the bundle sheath cells, the second peak had a dual location and the third peak was related to the mesophyll fraction. The mesophyll isoenzyme showed higher affinity for glycolate (Km 23 micromol x L(-1)) and a higher pH optimum (7.5-7.6) as compared to the bundle sheath isoenzyme (Km 65 micromol x L(-1), pH optimum 7.3). The bundle sheath isoenzyme was strongly activated by isocitrate and by succinate while the mesophyll isoenzyme was activated by isocitrate only slightly and was inhibited by succinate. It is concluded that although the glycolate oxidase activity is mainly attributed to the bundle sheath, conversion of glycolate to glyoxylate occurs also in the mesophyll tissue of C4 plant leaves.     

Morphological and biochemical modifications induced by a static magnetic field on Fusarium culmorum

The effects of the exposure to a static magnetic field (sMF) of 0.3 +/- 0.03 T on the Fusarium culmorum were investigated in vitro. sMF inhibition of mycelia growth was accompanied by morphological and biochemical changes. Fungal conidia germination and cell viability were also reduced. We provide evidence of the influence of sMF on Ca(2+)-dependent signal transduction pathways involved in conidia germination. Perturbation of these pathways by adding different compounds (i.e. CaCl(2), phorbol 12-myristate 13-acetate, neomycin, EGTA, LiCl) to the medium, suggested that exposed conidia are unable to mobilise calcium from intracellular stores and that the hindered mechanism may be IP(3)-dependent.     

Characterisation of SMN hybrid genes in Spanish SMA patients: de novo, homozygous and compound heterozygous cases

Autosomal recessive spinal muscular atrophy (SMA) is classified, by age of onset and maximal motor milestones achieved, into type I (severe form), type II (intermediate form) and type III (mild/moderate form). SMA is caused by mutations in the survival motor neuron telomeric gene (SMN1) and a centromeric functional copy of this gene (SMN2) exists, both genes being located at 5q13. Homozygous deletion of exons 7 and 8 of SMN1 has been detected in approx 85% of Spanish SMA patients regardless of their phenotype. Nineteen cases with the sole deletion of exon 7 but not exon 8 (2 cases of type I, 13 cases of type II, four cases of type III) were further analysed for the presence of SMN2-SMN1 hybrid genes. We detected four different hybrid structures. Most of the patients were carriers of a hybrid structure: centromeric intron 6- centromeric exon 7- telomeric exon 8 (CCT), with or without neuronal apoptosis-inhibitor protein (NAIP). In two patients, a different hybrid structure, viz. telomeric intron 6- centromeric exon 7- telomeric exon 8 (TCT), was detected with or without NAIP. A phenotype-genotype correlation comparing the different structures of the hybrid alleles was delineated. Type I cases in our series are attributable to intrachromosomal deletion with a smaller number of SMN2 copies. Most cases with hybrid genes are type II occurring by a combination of a classical deletion in one chromosome and a hybrid gene in the other. Type III cases are closely associated with homozygozity or compound heterozygozity for hybrid genes resulting from two conversion events and have more copies of hybrid genes and SMN2 than type I or II cases.     

Notentera ivanovi Joffe et al., 1997: a contribution to the question of phylogenetic relationships between ‘turbellarians’ and the parasitic Plathelminthes (Neodermata)

Notentera ivanovi is a parasitic platyhelminth found in the gut of a polychaete, Nephthys ciliata. N. ivanovi has no mouth, pharynx, or intestine; the dorsal epidermis of adult animals forms a thick pad which is very similar to gut epithelia even at the light microscopic level. Structure of ciliary rootlets and dermal glands with peculiar striated secretion bodies point to close relationships with the Fecampiidae, though other important characters imply placing the genus Notentera in a separate family. In mature sperm of N. ivanovi, the axonemes are fully incorporated; they are directed from proximal to distal, as in the Neodermata. We argue that new family, Notenteridae, should be included in the taxon Fecampiida. We also suggest that all Plathelminthes with neodermatan type of spermiogenesis (Fecampiidae, Urastomidae, and Neodermata) form a monophyletic branch within the Plathelminthes Neoophora. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photosynthesis, respiration, and chlorophylls in presenescent, regreened, and senescent leaves of forest herb Smyrnium perfoliatum L. (Apiaceae)

Smyrnium perfoliatum L. (Apiaceae), an endangered forest herb with only one main locality in South-West Slovakia (Devínska Kobyla in the Little Carpathian Mountains), is capable to recover chlorophylls at the end of the growing season. This regreening only within bracts was observed during two weeks before achieving the so-called “point of no return” that leads to the last stage of ontogenesis — leaf senescence. The effect not only of endogenous cytokinins on chlorophyll content and carbon dioxide exchange (photosynthesis, mitochondrial respiration, and photorespiration) is discussed but also of other factors such as strong irradiance, high temperature or drought stress on studied parameters was considered.     

Nitrogen availability influences the biochemical composition and photosynthesis of tank-cultivated Ulva rigida (Chlorophyta)

Physiological and biochemical changes in relation to inorganic nitrogen availability were studied for tank-cultivated Ulva rigida grown under nitrogen- enriched and nitrogen-depleted seawater. U. rigida was initially cultivated in nitrogen-enriched seawater (daily concentrations of NH4+ and NO3- + NO2- ranged between 0.5–1.7 and 0.06–0.15 mg L-1, respectively), then transferred to nitrogen-depleted seawater where photosynthetic capacity decreased to zero after 23 d. At the time (14 d) when photosynthetic rates were lower than 2.0 μmol O2 g-1 FW min-1 and strong bleaching had occurred, some algae were returned to the initial nitrogen-enriched seawater to study recovery from N-limited growth. Data on biochemical composition (chlorophylls, ash, caloric content, fatty acids and dietary fibres) and colouration varied significantly depending on the nitrogen conditions. C:N ratios correlated significantly with biochemical parameters. Fatty acid (FA) synthesis continued during the N-starvation period; saturated and mono-unsaturated FA increased to a maximun of 72.2%, while poly-unsaturated fatty acids (PUFA) decreased to 27.7%. During the N-enriched recovery period, the reverse was found. C:N ratios above 10 correlated with carbohydrate synthesis as shown by the dietary fibre level. Under nitrogen enriched conditions, C:N ratios decreased along with a decrease in fibre level. Under controlled conditions, nitrogen represents a major influence on the development of intensive tank cultivation of Ulva rigida, not only by affecting parameters closely related to nitrogen metabolism but also some clearly influenced by carbon uptake. This revised version was published online in June 2006 with corrections to the Cover Date.     

Displacement of SERCA from SR lipid caveolae-related domains by Bcl-2: a possible mechanism for SERCA inactivation

Bcl-2 exerts its anti-apoptotic effect in part through the regulation of Ca2+ homeostasis at the level of the endoplasmic reticulum. Earlier, we demonstrated that a truncated form of Bcl-2, Bcl-2delta21, interacts with and destabilizes the skeletal muscle sarco/endoplasmic reticulum Ca-ATPase (SERCA) [Dremina, E. S., Sharov, V. S., Kumar, K., Zaidi, A., Michaelis, E. K., and Sch?neich, C. (2004) Biochem. J. 383, 361-370]. Here we show that (i) the transmembrane (TM) domain of Bcl-2 accelerates SERCA inactivation, (ii) both Bcl-2delta21 and full-length Bcl-2 selectively interact with SERCA1, and (iii) the inactivation of SERCA is accompanied by a translocation of SERCA from caveolae-related domains (CRD) of the sarcoplasmic reticulum (SR). In rat skeletal muscle SR, intact SERCA1 was detected only in the CRD fractions of a sucrose density gradient. Co-incubation of SR with either Bcl-2delta21 or full-length Bcl-2 resulted in both the appearance of Bcl-2delta21 or Bcl-2 in the fractions containing SERCA1 and translocation of SERCA1 from CRD fractions; the latter effect correlated with the loss of the Ca-ATPase activity of the protein.     

Transgenomic metabolic interactions in a mouse disease model: interactions of Trichinella spiralis infection with dietary Lactobacillus paracasei supplementation

Irritable Bowel Syndrome (IBS) is a common multifactorial intestinal disorder for which the aetiology remains largely undefined. Here, we have used a Trichinella spiralis (T. spiralis)-induced model of post-infective IBS, and the effects of probiotic bacteria on gut dysfunction have been investigated using a metabonomic strategy. A total of 44 mice were divided into four groups: an uninfected control group and three T. spiralis-infected groups, one as infected control and the two other groups subsequently treated with either Lactobacillus paracasei (L. paracasei) NCC2461 in spent culture medium (SCM) or with L. paracasei-free SCM. Plasma, jejunal wall and longitudinal myenteric muscle samples were collected at day 21 post-infection. An NMR-based metabonomic approach characterized that the plasma metabolic profile of T. spiralis-infected mice showed an increased energy metabolism (lactate, citrate, alanine), fat mobilization (acetoacetate, 3-D-hydroxybutyrate, lipoproteins) and a disruption of amino acid metabolism due to increased protein breakdown, which were related to the intestinal hypercontractility. Increased levels of taurine, creatine and glycerophosphorylcholine in the jejunal muscles were associated with the muscular hypertrophy and disrupted jejunal functions. L. paracasei treatment normalized the muscular activity and the disturbed energy metabolism as evidenced by decreased glycogenesis and elevated lipid breakdown in comparison with untreated T. spiralis-infected mice. Changes in the levels of plasma metabolites (glutamine, lysine, methionine) that might relate to a modulation of immunological responses were also observed in the presence of the probiotic treatment. The work presented here suggests that probiotics may be beneficial in patients with IBS.