Characterization and biotechnological application of an acid alpha-galactosidase from Tachigali multijuga Benth. seeds

Tachigali multijuga Benth. seeds were found to contain protein (364 mg g(-1)dwt), lipids (24 mg g(-1)dwt), ash (35 mg g(-1)dwt), and carbohydrates (577 mg g(-1)dwt). Sucrose, raffinose, and stachyose concentrations were 8.3, 3.0, and 11.6 mg g(-1)dwt, respectively. alpha-Galactosidase activity increased during seed germination and reached a maximum level at 108 h after seed imbibition. The alpha-galactosidase purified from germinating seeds had an M(r) of 38,000 and maximal activity at pH 5.0-5.5 and 50 degrees C. The enzyme was stable at 35 degrees C and 40 degrees C, but lost 79% of its activity after 30 min at 50 degrees C. The activation energy (E(a)) values for p-nitrophenyl-alpha-d-galactopyranoside (pNPGal) and raffinose were 13.86 and 4.75 kcal mol(-1), respectively. The K(m) values for pNPGal, melibiose, raffinose, and stachyose were 0.45, 5.37, 39.62 and 48.80 mM, respectively. The enzyme was sensitive to inhibition by HgCl(2), SDS, AgNO(3), CuSO(4), and melibiose. d-Galactose was a competitive inhibitor (K(i)=2.74 mM). In addition to its ability to hydrolyze raffinose and stachyose, the enzyme also hydrolyzed galactomannan.     

Conventional and transgenic strategies to enhance the acid soil tolerance of barley

The aluminum (Al³⁺) tolerance of barley cultivars predominately from Brazil was compared to that of cultivars from other countries, wild barley accessions, and a transgenic line (L5) over-expressing TaALMT1, the major Al³⁺ tolerance gene from wheat. After screening conventional germplasm for Al³⁺ tolerance in hydroponics, 18 genotypes were further characterized in a short-term soil experiment. Among the Brazilian cultivars, Antarctica 01 and BRS Mariana showed the greatest relative root length (RRL) in acid soil. However, these cultivars were significantly less tolerant than the foreign cultivars Dayton (USA) and Murasakimochi (Japan) and the transgenic line L5 which out-performed all conventional genotypes. In long-term growth trials, the transgenic line produced the greatest relative root and relative shoot dry weight. Relative grain yield was greatest in the transgenic line and Dayton. All genotypes were also scored for two genetic markers linked to HvAACT1, the major Al³⁺ tolerance gene in barley. One marker detects a 1-kb insertion in the promoter that increases gene expression and leads to increased Al³⁺-activated citrate efflux from root apices. The other marker detects a 21-bp indel downstream of the coding region. The 1-kb insertion was only detected in Dayton and Murasakimochi that were the best performing cultivars among the non-transgenic germplasm. Interestingly, the Brazilian cultivars with an intermediate level of tolerance, Antarctica 01 and BRS Mariana, lacked the 1-kb insertion but had enhanced HvAACT1 expression compared to an Al³⁺-sensitive cultivar. No clear correlation was observed between Al³⁺ tolerance and the 21-bp indel marker in the short-term soil trials. We conclude that improved Al³⁺ tolerance in barley could be achieved by combining the best allele of HvAACT1 along with TaALMT1 as a transgene.     

Synthesis and crystal structure of the MgCl2(CH3COOC2H5)2· (CH3COOC2H5) adduct

The reaction of α-MgCl₂ with boiling ethyl acetate affords MgCI₂(CH₃COOC₂H₅)₂· (CH₃COOC₂H₅), which is obtained as crystals suitable for X-ray analysis only from the mother liquor. M=315.5, orthorhombic, space group P2₁22₁ (No. 18), a=25.077(3), b=8.616(1), c=7.345(1) Å, V=1587.0(3) ų, Z=4, D_x=1.32 g cm⁻³,λ A(Mo Kα)=0.71069 Å, μ=4.17 cm⁻¹, F(000)=664, T=298 K, observed reflections: 1667, R=0.059 and R_w=0.069. The structure is composed of polymeric chains of MgCl₂(CH₃COOC₂H₅₎₂ and the ethyl acetate molecules occupy a mutually trans position.     

Effects of the parasite Probopyrus ringueleti (Isopoda) on glucose, glycogen and lipid concentration in starved Palaemonetes argentinus (Decapoda)

Effects of the branchial ectoparasite isopod Probopyrus ringueleti on the utilization of glucose, glycogen and total lipids on starved shrimp Palaemonetes argentinus were evaluated, as well as the isopod responses to host starvation. Shrimp were maintained for 12 d under laboratory conditions. Parasitized and unparasitized shrimp were starved for 15 d, and glucose, glycogen and total lipid concentrations were determined at 0, 24, 72, 168 and 360 h of starvation. During starvation, control animals (unparasitized) preferentially metabolized lipids and preserved their carbohydrate reserves. Parasitized shrimp had lower lipid concentrations than unparasitized shrimp, and preferentially metabolized carbohydrates. Bopyrids displayed a similar response, with glycogen depleted at the beginning of the starvation period followed by subsequent reestablishment. Our results demonstrated that bopyrids affect host energy allocation. The lower initial lipid concentration of parasitized shrimp suggested that the host is disadvantaged from both food deprivation and isopod nutritional demands. A possible dependency of P. ringueleti on the mechanisms that control host metabolic processes was also suggested.     

Plasmonic Coupling in Er3+:Au Tellurite Glass

In this paper, we report on luminescence and absorbance effects of Er⁺³:Au-doped tellurite glasses synthesized by a melting-quenching and heat treatment technique. After annealing times of 2.5, 5.0, 7.5, and 10.0 h, at 300 °C, the gold nanoparticles (GNP) effects on the Er⁺³ are verified from luminescence spectra and the corresponding levels lifetime. The localized surface plasmon resonance around 800 nm produced a maximum fluorescence enhancement for the band ranging from 800 to 840 nm, corresponding to the transitions ⁴H_11/2 → ⁴I_13/2 (805 nm) and ⁴S_3/2 → ⁴I_13/2 (840 nm), with annealing time till 7.5 h. The measured lifetime of the levels ⁴H_11/2 and ⁴S_3/2 confirmed the lifetime reduction due to the energy transfer from the GNP to Er⁺³, causing an enhanced photon emission rate in these levels.     

Biochemical and physiological adaptations in the estuarine crab Neohelice granulata during salinity acclimation

Neohelice granulata (Chasmagnathus granulatus) is an intertidal crab species living in salt marshes from estuaries and lagoons along the Atlantic coast of South America. It is a key species in these environments because it is responsible for energy transfer from producers to consumers. In order to deal with the extremely marked environmental salinity changes occurring in salt marshes, N. granulata shows important and interesting structural, biochemical, and physiological adaptations at the gills level. These adaptations characterize this crab as a euryhaline species, tolerating environmental salinities ranging from very diluted media to concentrated seawater. These characteristics had led to its use as an animal model to study estuarine adaptations in crustaceans. Therefore, the present review focuses on the influence of environmental salinity on N. granulata responses at the ecological, organismic and molecular levels. Aspects covered include salinity tolerance, osmo- and ionoregulatory patterns, morphological and structural adaptations at the gills, and mechanisms of ion transport and their regulation at the gills level during environmental salinity acclimation. Finally, this review compiles information on the effects of some environmental pollutants on iono- and osmoregulatory adaptations showed by N. granulata.     

Heat stress negatively affects physiology and morphology during germination of Ormosia coarctata (Fabaceae,Papilionoideae)

Research on the morphophysiological behavior of forest seeds during germination with respect to climate change is scarce. To date, there have been no studies on the biochemical or morphological aspects of Ormosia spp. In this study, we subjected Ormosia coarctata seeds to various temperature conditions to investigate temperature-dependent impacts on morphology, reactive oxygen species (ROS) generation, antioxidant systems, and storage systems. Analyses were performed on seeds exposed to 25, 35, and 40 °C for 48, 96, and 144 h. The morphology was evaluated by radiation using a Faxitron MX-20 device. ROS production (superoxide anion and hydrogen peroxide), malonaldehyde (MDA), carbonylated proteins, antioxidant enzyme activity (superoxide dismutase [SOD], ascorbate peroxidase [APX], catalase [CAT], and peroxidase [POX]), β-carotene, lycopene, glucose, and reserve enzyme activity (α- and β-amylase, lipase, and protease) were analyzed by spectrophotometry. Heat stress (40 °C) decreased germination by 76.2% and 78.1% (compared to 25 and 35 °C, respectively), caused damage to the external morphology of the seed, increased the content of ROS, MDA, and carbonylated proteins, and reduced APX, CAT, and POX activity. Furthermore, heat stress decreased glucose content and α-amylase activity. These results suggest that an increase of 5 °C in temperature negatively affects germination, promotes oxidative stress, and induces deterioration in O. coarctata seeds.

     

Assessment of genetic diversity in Brazilian barley using SSR markers

Barley is a major cereal grown widely and used in several food products, beverage production and animal fodder. Genetic diversity is a key component in breeding programs. We have analyzed the genetic diversity of barley accessions using microsatellite markers. The accessions were composed of wild and domesticated barley representing genotypes from six countries and three breeding programs in Brazil. A total of 280 alleles were detected, 36 unique to Brazilian barley. The marker Bmag120 showed the greatest polymorphism information content (PIC), with the highest mean value found on chromosome three, and the lowest on chromosomes four and six. The wild accessions presented the highest diversity followed by the foreign genotypes. Genetic analysis was performed using Principal Coordinates Analysis, UPGMA clustering, and Bayesian clustering analysis implemented in Structure. All results obtained by the different methods were similar. Loss of genetic diversity has occurred in Brazilian genotypes. The number of alleles detected in genotypes released in 1980s was higher, whereas most of the cultivars released thereafter showed lower PIC and clustered in separate subgroups from the older cultivars. The use of a more diverse panel of genotypes should be considered in order to exploit novel alleles in Brazilian barley breeding programs.