Tribute in memory of Jacques Breton (1942–2018)

Photosynthesis Research - Jacques Breton spent his 39 years of professional life at Saclay, a center of the French Atomic Energy Commission. He studied photosynthesis with various advanced...     

Hydrogen peroxide (H<Subscript>2</Subscript>O<Subscript>2</Subscript>) and methyl-β-cyclodextrin (MβCD) down regulate caveolin expression in human lens epithelial cells (HLECs)

Oxidative stimulation induced by hydrogen peroxide (H₂O₂) on human lens epithelial cells (HLECs) was performed to observe the effects on cell viability and caveolin expression, and cholesterol depletion in HLECs caused by methyl-β-cyclodextrin (MβCD) was also studied. SRA01/04 HLECs were exposed to H₂O₂ or MβDC of various concentrations and durations. We used a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to measure the effect of H₂O₂ on the viability of SRA01/04 HLECs. The distributions of caveolins after oxidative stimulation were probed by fluorescence microscopy and laser scanning confocal microscopy. Immunoblotting was performed to analyze alterations of caveolins expression. We observed that the viability of SRA01/04 HLECs under 0.1 mM H₂O₂ for 10 min or longer was significantly reduced (*p < 0.05, F = 11.63). Laser scanning microscopy showed immunofluorescent caveolins in SRA01/04 HLECs under 0.1 mM H₂O₂ for 10 min or longer; caveolins were largely confined to intracellular domains. Western blots showing both membrane and total caveolin protein (22 kDa) levels in SRA01/04 HLECs treated with 0.1, 0.2, 0.5, or 1.0 mM H₂O₂ for 30 min were significantly reduced, compared with the untreated (*p < 0.05, F = 6.149, or *p < 0.05, F = 14.489, respectively). In addition, the membrane and total caveolin protein level after being treated with 0.1 mM H₂O₂ (*p < 0.05, F = 6.843, or *p < 0.05, F = 7.944, respectively) for different durations also down regulated. Fluorescence microscopy also showed that phosphorylated caveolin-1 was distributed near the focal adhesions of the cells. This study concludes that the responses of HLECs to oxidative stress may include down regulation of caveolin and phosphorylation of caveolin-1 on tyrosine 14 and that MβCD also down regulates caveolin while depleting cholesterol in HLECs. Published in Russian in Molekulyarnaya Biologiya, 2007, Vol. 41, No. 6, pp. 994–1001. The article was submitted by the authors in English.     

Effects of phenol in antioxidant metabolism in matrinxã, Brycon amazonicus (Teleostei; Characidae)

Parameters of the antioxidant defense systems of Brycon amazonicus (matrinx?--a neotropical fish) exposed to phenol for 96 h plus the recovery over 1 and 2 weeks were studied in erythrocytes and liver. Hematocrit increase was observed during phenol exposure and recovery for 1 week. Total superoxide dismutases (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) did not change during phenol exposure. Erythrocyte glucose-6-phosphate dehydrogenase (G6PDH) increased during that period while catalase (CAT) activity decreased during phenol exposure and recovery for 2 weeks. In the liver, SOD and CAT did not change, whereas GPx increased in the first week of recovery and decreased after 2 weeks. A late response was observed for G6PDH activity which increased only at the second week. Ascorbate concentration in the brain decreased during phenol exposure and increased over recovery. From our results it appears that the oxidative stress was limited in matrinx? exposed to phenol, but seemed to occur during the recovery period.     

Thermal effects in rainbow trout (Oncorhynchus mykiss) F1 embryos (farmed female × wild thermal-resistant male)

The aim of this work was to investigate the response of rainbow trout embryos (Oncorhynchus mykiss) (i.e., survival, size at hatching, time to hatching, malformations) to four incubation temperatures (5.8, 8.9, 14.0 and 16.8°C), taking into account the origin of the male parental genome and comparing pure farmed and F1 embryos (farmed female × wild thermal-resistant male). Several consequences of thermal stress were observed: lower accumulated thermal units (ATU) at hatching at high temperatures, and lower survival, shorter hatched free embryos and less-consumed yolk sac at extreme temperatures. The effect of the thermal-adapted male parental genome was shown only in the lower percentage of incompletely hatched free embryos in the F1 families. It appears that to obtain greater modification of thermal performance during early development, the adapted genome of the wild thermal-resistant population has to be included through maternal inheritance, thus producing a stabilized strain selected for domesticity, growth and thermal adaptation.     

Analysis of <Emphasis Type="Italic">GJB6</Emphasis> (Сx30) and <Emphasis Type="Italic">GJB3</Emphasis> (Сx31) genes in deaf patients with monoallelic mutations in <Emphasis Type="Italic">GJB2</Emphasis> (Сx26) gene in the Sakha Republic (Yakutia)

Тhe DNA testing of autosomal recessive deafness type 1A (DFNB1A, MIM 220290) is complicated when deaf patients have only monoallelic (heterozygous) recessive mutations in the GJB2 (Сх26) gene that is uninformative for establishment of diagnosis. Such patients may be “random” heterozygous carriers of GJB2 mutations as well as have the mutant allele in a cis-regulatory region of GJB2 gene, in element genes encoding other connexins: GJB6 (Сх30) or GJB3 (Сх31). Previous studies of genetic causes of hearing loss in patients from Yakutia were directed to search for only mutations in the GJB2 gene, and the DNA diagnostics was uninformative for 9.7% (38/393) of the patients with monoallelic GJB2 mutations. In this work the search for mutations in genes GJB3 and GJB6 and two deletions с.del(GJB6-D13S1830) and с.del(GJB6-D13S1854) to the cis-regulatory region of GJB2 gene was conducted in 35 patients with GJB2 monoallelic mutations and in 104 normal hearing individuals. The genes studied are two synonymous substitution c.489G>A (р.Leu163Leu) (GJB6) and c.357C>T (р.Asn119Asn) (GJB3) have been found, probably do not have clinical significance, and two nonsynonymous substitution c.301G>A (p.Glu101Lys) (GJB6) and с.580G>A (p.Ala194Thr) (GJB3). Additional experimental evidences are needed for confirmation of pathogenic significance of detected nonsynonymous substitutions in development of hearing loss in studied patients. Diagnosis of the DFNB1A was confirmed in only one patient, who was discovered by the deletion с.del(GJB6-D13S1830) (GJB2) in combination with a recessive mutation с.35delG (GJB2). In general, our results indicate low contribution of mutations in genes GJB6 and GJB3 in hearing loss etiology in Yakutia.     

Evolution of mixed-linkage (1 -> 3, 1 -> 4)-β-D-glucan (MLG) and xyloglucan in Equisetum (horsetails) and other monilophytes

Background and Aims

Horsetails (Equisetopsida) diverged from other extant eusporangiate monilophytes in the Upper Palaeozoic. They are the only monilophytes known to contain the hemicellulose mixed-linkage (1 → 3, 1 → 4)-β-d-glucan (MLG), whereas all land plants possess xyloglucan. It has been reported that changes in cell-wall chemistry often accompanied major evolutionary steps. We explored changes in hemicelluloses occurring during Equisetum evolution.

Methods

Hemicellulose from numerous monilophytes was treated with lichenase and xyloglucan endoglucanase. Lichenase digests MLG to di-, tri- and tetrasaccharide repeat-units, resolvable by thin-layer chromatography.

Key Results

Among monilophytes, MLG was confined to horsetails. Our analyses support a basal trichotomy of extant horsetails: MLG was more abundant in subgenus Equisetum than in subgenus Hippochaete, and uniquely the sister group E. bogotense yielded almost solely the tetrasaccharide repeat-unit (G4G4G3G). Other species also gave the disaccharide, whereas the trisaccharide was consistently very scarce. Tetrasaccharide : disaccharide ratios varied interspecifically, but with no consistent difference between subgenera. Xyloglucan was scarce in Psilotum and subgenus Equisetum, but abundant in subgenus Hippochaete and in the eusporangiate ferns Marattia and Angiopteris; leptosporangiate ferns varied widely. All monilophytes shared a core pattern of xyloglucan repeat-units, major XEG products co-chromatographing on thin-layer chromatography with non-fucosylated hepta-, octa- and nonasaccharides and fucose-containing nona- and decasaccharides.

Conclusions

G4G4G3G is the ancestral repeat-unit of horsetail MLG. Horsetail evolution was accompanied by quantitative and qualitative modification of MLG; variation within subgenus Hippochaete suggests that the structure and biosynthesis of MLG is evolutionarily plastic. Xyloglucan quantity correlates negatively with abundance of other hemicelluloses; but qualitatively, all monilophyte xyloglucans conform to a core pattern of repeat-unit sizes.     

Control of the flat-headed root borer <Emphasis Type="Italic">Capnodis tenebrionis</Emphasis> (Linné) (Coleoptera: Buprestidae) with the entomopathogenic nematode <Emphasis Type="Italic">Steinernema carpocapsae</Emphasis> (Weiser) (Nematoda: Steinernematidae) in a chitosan formulation in apricot orchards

Entomopathogenic nematodes Steinernema carpocapsae were applied in a chitosan formulation (Biorend R^®) to control the flat-headed rootborer Capnodis tenebrionis (Coleoptera: Buprestidae) in 5 field trials in the province of Valencia, Spain. Application was performed during spring and summer into the soil around apricot trees at densities of 1 and 1.5 million infective dauer juveniles per tree through drip irrigation, injection or by a drench. For evaluation of the control effect the roots of 106 trees were excavated, the cortex removed and living and dead insects were sampled. Dead larvae were dissected and checked for nematode infestation. Control of C. tenebrionis larvae was between 75% and 90%. No influence of the application method, nematode density or time of application on the control effect was recorded. Recovery of the infested trees was observed already in the season following nematode application. Due to the two year life cycle of the insect with egg laying from May to August, applications during spring and autumn are recommended.     

Yearly variation in polygyny in the termite <Emphasis Type="Italic">Macrotermes michaelseni</Emphasis> (Sjöstedt)

Summary Macrotermes michaelseni, an abundant termite species in semi-arid ecosystems of eastern Africa, exhibits considerable fluctuations in the proportion of polygynous colonies across years (between 5 and 50%). We found a negative correlation between rainfall and the proportion of polygynous colonies with a time lag of two years. A decrease in the percentage of polygynous colonies was particularly obvious in 1999 and 2000, two years after an El Niño-event. Rainfall and subsequent primary production seem to influence the degree of polygyny. Variation in the proportion of polygynous colonies could be due to several mutually non-exclusive factors, including better survival of polygynous colonies during years with low resource availability and increased aggression between nestmate queens with decreasing resource availability. Evaluating several lines of circumstantial evidence we suggest that the degree of polygyny depends on ecological factors.Received 11 July 2003; revised 14 October and 3 February 2004; accepted 9 March 2004.     

10,000 years in isolation? Honeybees (<Emphasis Type="Italic">Apis mellifera</Emphasis>) in Saharan oases

After the transition from a savannah to a desert about 10,000 years ago the isolated Saharan oases offer a unique case for studying the effect of population fragmentation and isolation over a period of many thousand years. We use the honeybee, Apis mellifera, as a test system because they are an abundant wild species in the African dry savannahs but are particularly sensitive to drift and bottlenecks in small isolated populations due to the small effective size resulting from male haploidy, the sex determination system and sociality. We compared the non-fragmented coastal population with the oases of Brak and Kufra using 15 polymorphic microsatellite loci assessing the mating frequency, colony density, gene diversity, and population differentiation. We found that the honeybee population of the remote oasis of Kufra is well isolated whereas those of the oasis of Brak and the coastal regions show genetic foot prints of introgression by commercial beekeeping. The isolated Kufra population showed no indications of inbreeding suggesting that the endemic population size is sufficient to ensure sustainable local survival.     

CST-II’s recognition domain for acceptor substrates in α-(2→8)-sialylations

CST-II is a bacterial sialyltransferase known for its ability to perform α-(2→8)-sialylations using GM₃ related trisaccharide substrates. Previously, we probed the enzyme’s substrate specificity and developed an efficient synthesis for α-(2→8)-oligosialosides, and we suggested that CST-II could have a very small substrate recognition domain. Here we report our full studies on CST-II’s recognition feature for acceptor substrates. The current study further demonstrates the versatility of CST-II in preparing complex oligosaccharides that contain α-(2→8)-oligosialyl moieties.     

Sperm Numbers and Female Fertility in the Moth Plodia interpunctella (Hübner) (Lepidoptera; Pyralidae)

I investigated two possible reasons for remating in female Plodia interpunctella: i) females remate to obtain sufficient sperm to maintain fertility; and ii) male investment in non-sperm components increases female fecundity and longevity. The number of sperm and the mass of the spermatophore transferred by males decreases on successive matings. Sperm numbers and potential male investment were varied by allowing females to mate either once or twice with males either on their first or second mating. Females receiving a single small spermatophore containing few sperm (from a male on his second mating) had sufficient sperm to fertilize all their eggs. Females did not show increased fecundity or longevity as a result of obtaining more spermatophore material. I discuss why females remate when they already have sufficient sperm to fertilize all their eggs.     

Global diversity of oligochaetous clitellates (“Oligochaeta”; Clitellata) in freshwater

One of the predicted consequences of climate change is an increase in the occurrence of extreme rainfall and a subsequent increase in frequency of high flow events in rivers. High flow events have the potential to impact estuarine communities like mussel assemblages due to decreased salinity and/or the transport of sediments, organic matter and nutrients from the terrestrial environment to the estuary. The impact of two high flow events was investigated using mussels located within the Conwy estuary, North Wales, using the ‘Beyond BACI’ approach. Three study sites were chosen, the potentially impacted site (Conwy) and two control sites located outside the estuary. Sampling took place over 18 months with samples being collected before and after each event. On each sampling occasion, the following data were collected: the total haemocyte count (THC) and condition index (CI) of the mussels and the diversity (Hlog_e) of their associated macrofauna. A significant effect of the first event (22nd October 2004) was found on the CI of the Conwy mussels, whereas a significant effect of the second event (10th October 2005) was found on mussel THC. No effect of either event was found on the diversity of the associated fauna. The results of this study suggest that any increase in the number or intensity of heavy precipitation or high flow events have potential implications for the health and resilience of estuarine mussel populations. Guest editors: J. Davenport, G. Burnell, T. Cross, M. Emmerson, R. McAllen, R. Ramsay & E. Rogan Challenges to Marine Ecosystems     

Microsatellite assessment of the genetic diversity in indigenous populations of curimba (<Emphasis Type="Italic">Prochilodus argenteus</Emphasis>) in the São Francisco river (Brazil)

The freshwater fish curimba (Prochilodus argenteus) is an endemic species of the São Francisco River basin, with great aquaculture potential. The construction of several hydroelectric power dams along the river, and the pulsed releases of water from these dams altered and degraded the native fish habitats, which led to the development of a hatchery-reared fingerling restocking program. A comprehensive genetic baseline evaluation of the indigenous populations of curimba and of a hatchery stock was done using microsatellite markers. Pairwise F _ST values, Bayesian analysis and the number of migrants per generation were used to illustrate the genetic structure of the curimba populations along almost 3000 km of the river, suggesting the existence of three units of conservation: one in the Upper, a second in the Middle and a third including part of the Middle, Submiddle and Lower stretches. We have analyzed the genetic contribution of hatchery stock releases in two stretches of the river using individual admixture coefficients; and the results showed that admixture makes a negligible contribution to indigenous recruitment. We discussed about supplementation programs for this river from the perspective of three units of conservation and the risks associated with using domesticated fish.     

Mitochondria-targeted antioxidant SkQ1 (10-(6′-plastoquinonyl)decyltriphenylphosphonium bromide) inhibits mast cell degranulation <Emphasis Type="Italic">in vivo</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis>

The therapeutic effect of mitochondria-targeted antioxidant 10-(6′-plastoquinonyl)decyltriphenylphosphonium bromide (SkQ1) in experimental models of acute inflammation and wound repair has been shown earlier. It was suggested that the antiinflammatory activity of SkQ1 is related to its ability to suppress inflammatory activation of the vascular endothelium and neutrophil migration into tissues. Here, we demonstrated that SkQ1 inhibits activation of mast cells (MCs) followed by their degranulation and histamine release in vivo and in vitro. Intraperitoneal injections of SkQ1 in the mouse air-pouch model reduced the number of leukocytes in the air-pouch cavity and significantly decreased the histamine content in it, as well as suppressing MC degranulation in the air-pouch tissue. The direct effect of SkQ1 on MCs was studied in vitro in the rat basophilic leukemia RBL-2H3 cell line. SkQ1 inhibited induced degranulation of RBL-2H3 cells. These results suggest that mitochondrial reactive oxygen species are involved in the activation of MCs. It is known that MCs play a crucial role in regulation of vascular permeability by secreting histamine. Suppression of MC degranulation by SkQ1 might be a significant factor in the antiinflammatory activity of this mitochondria-targeted antioxidant.     

Valbro : un nouveau site à vertébrés de l’Oligocène inférieur (MP 22) de France (Quercy). II – Oiseaux (Aves)

The bird remains from Valbro belong only to three taxa, Paraortyx lorteti, Archaeotrogon venustus, and A. zitteli. This association makes it possible to ascribe to this locality an early Oligocene age, reference-levels MP 22 or MP 23, which is in agreement with the age given by the mammals.