Time-resolved infrared spectroscopy in the study of photosynthetic systems

Time-resolved (TR) infrared (IR) spectroscopy in the nanosecond to second timescale has been extensively used, in the last 30 years, in the study of photosynthetic systems. Interesting results have also been obtained at lower time resolution (minutes or even hours). In this review, we first describe the used techniques—dispersive IR, laser diode IR, rapid-scan Fourier transform (FT)IR, step-scan FTIR—underlying the advantages and disadvantages of each of them. Then, the main TR-IR results obtained so far in the investigation of photosynthetic reactions (in reaction centers, in light-harvesting systems, but also in entire membranes or even in living organisms) are presented. Finally, after the general conclusions, the perspectives in the field of TR-IR applied to photosynthesis are described.     

The Psilostomidae Looss, 1900 (<Emphasis Type="Italic">sensu stricto</Emphasis>) (Digenea: Echinostomatoidea): description of three new genera and a key to the genera of the family

Three new psilostomid genera, Byrdtrema n. g., Longisaccus n. g. and Macracetabulum n. g., each with a single species, are described from ducks, Aix sponsa (L.) and Bucephala albeola (L.) in North America. Byrdtrema n. g. and Macracetabulum n. g. possess a bipartite seminal vesicle and share this character with four psilostomid genera, Grysoma Byrd, Bogitsh & Maples, 1961, Neopsilotrema Kudlai, Pulis, Kostadinova & Tkach, 2016, Psilostomum Looss, 1899 and Psilotornus Byrd & Prestwood, 1969. Byrdtrema n. g. differs from Macracetabulum n. g. in the shape of the body (elongate vs elongate-oval); the position of the ventral sucker (in first third of body vs just pre-equatorial); the shorter forebody; as well as in the smaller size of the eggs in relation to body length. Both new genera differ from (i) Grysoma by the nature of the vitellarium (large, compact follicles with small vitelline cells vs weakly defined follicles with large vitelline cells, respectively) and the smaller size of the eggs in relation to body length; (ii) Psilostomum in the posterior extend of the cirrus-sac in relation to ventral sucker (slightly posterior vs more posterior), the location of the genital pore (at the level of oesophagus vs just postbifurcal), the shorter length of uterine and longer post-testicular fields in relation to body length, and the anterior limits of vitellarium (at the level of ventral sucker vs posterior to ventral sucker); (iii) Psilotornus by the presence of a muscular pharynx (vs absent or rudimentary) and the location of the cirrus-sac (antero-dorsal to ventral sucker or more posterior vs entirely anterior to ventral sucker) and ovary (in hindbody vs in forebody). Byrdtrema n. g. differs from Neopsilotrema in the shape of the body (elongate vs subspherical to elongate-oval) and ventral sucker (elongate-oval vs subspherical to transversely oval), the shorter forebody and smaller eggs in relation to body length. Macracetabulum n. g. differs from Neopsilotrema by the shape of the ventral sucker (elongate-oval vs subspherical to transversely oval), the anterior limits of vitellarium (level of middle of ventral sucker vs level of intestinal bifurcation or anterior testis); and the slightly smaller size of eggs in relation to body length. Among the psilostomid genera, Longisaccus n. g. shows close affinities to Psilochasmus Lühe, 1909 in the presence of the long cirrus-sac and tubular internal seminal vesicle but can be clearly distinguished from the latter by the absence of the retractile tail-like process. In combination with molecular data, the above differences justify the recognition of three new genera. A key to the genera of the Psilostomidae is provided.     

<Emphasis Type="Italic">Lobocapillaria austropacifica</Emphasis> n. g., n. sp. (Nematoda: Capillariidae) from the obtuse barracuda <Emphasis Type="Italic">Sphyraena obtusata</Emphasis> Cuvier (Sphyraenidae,Perciformes) off eastern Australia

Based on light and scanning electron microscopical studies, a new nematode parasite, Lobocapillaria austropacifica n. sp. (Capillariidae), is described from the gall-bladder of the marine fish (obtuse barracuda) Sphyraena obtusata Cuvier (Perciformes: Sphyraenidae) from off the eastern Pacific coast of Australia, for which a new genus Lobocapillaria n. g. is established. This new genus is mainly characterised by a single row of stichocytes, the presence of two large, conspicuously elongated lateral caudal lobes and a pair of subventral papillae at their base in males, a flat spicule distended laterally towards its proximal end and provided with superficial rough transverse grooves, a spicular canal and a very long, aspinose spicular sheath with a conspicuous expansion near its proximal end when evaginated. Capillaria sphyraeni Parukhin, 1971 is transferred to Lobocapillaria as L. sphyreni (Parukhin, 1971) n. comb. A key to capillariid genera containing species parasitic in fishes is provided.     

Filling the gaps in the classification of the Digenea Carus, 1863: systematic position of the Proterodiplostomidae Dubois, 1936 within the superfamily Diplostomoidea Poirier, 1886, inferred from nuclear and mitochondrial DNA sequences

The Diplostomida Olson, Cribb, Tkach, Bray & Littlewood, 2003 is the less diverse order of the two orders within the subclass Digenea Carus, 1863 and is currently classified into three superfamilies, i.e. Brachylaimoidea Joyeux & Foley, 1930, Diplostomoidea Poirier, 1886, and Schistosomatoidea Stiles & Hassall, 1898. Although the suprageneric-level relationships have been elucidated with the use of molecular markers, the lack of representation of some groups obscure the phylogenetic relationships among families, rendering the classification unstable. Here, we tested the phylogenetic position of the family Proterodiplostomidae Dubois, 1936 based on partial 28S rDNA and complete 18S rDNA sequences for Crocodilicola pseudostoma (Willemoes-Suhm, 1870), a crocodile parasite that has been found as a progenetic metacercaria parasitising the pale catfish Rhamdia guatemalensis (Günther) in Mexico and in other siluruforms in the Neotropics. We augmented the representation of the species, genera and families within the Diplostomida, including mostly representatives of the superfamily Diplostomoidea, and assembled a dataset that contains 49 species for the 28S rRNA gene, and 45 species for the 18S rRNA gene. Additionally, we explored the phylogenetic signal of the mitochondrial gene cox1 in reconstructing the phylogenetic relationships of selected members of the superfamily. Our analyses showed that the family Proterodiplostomidae is the sister taxon to the paraphyletic Diplostomidae Poirier, 1886 and Strigeidae Railliet, 1919, with Cyathocotylidae Mühling, 1898 + Brauninidae Wolf, 1903 as their sister group. Analysis of concatenated 18S + 28S sequences revealed the Liolopidae Odhner, 1912 as the basal group of the superfamily Diplostomoidea, although analyses of independent datasets showed that the position of this family remains uncertain. Analysis based on cox1 unequivocally resolved the Proterodiplostomidae as the sister taxon to the Diplostomidae and Strigeidae, although the Cyathocotylidae was nested in a different clade, along with brachylaimoids and schistosomatoids.     

In vitro induction of tetraploid <Emphasis Type="Italic">Ziziphus jujuba</Emphasis> Mill. var. <Emphasis Type="Italic">spinosa</Emphasis> plants from leaf explants

The genetic manipulation of Capsicum has been unsuccessful, and a large bottleneck to transferring the desired genes is due to the difficulty in regenerating whole plants through tissue culture because of its highly recalcitrant and high genotype specificity. This study aimed to investigate and establish rapid shoot regeneration from the proximal ends of the leaves of Capsicum frutescens KT-OC and BOX-RUB varieties. A maximum of 8–10 shoot buds were obtained from the margins of the proximal portion of a cotyledonary leaf explant of C. frutescens variety KT-OC on medium I containing 44.44 µM 6-benzylaminopurine (BA), 5.71 µM indole-3-acetic acid (IAA), 10 µM silver nitrate (AgNO₃) and 1.98 mg L^?1 2-(N-morpholine) ethane sulphonic acid within 4 weeks of incubation, of which 60% of explants responded in terms of shoot buds. Petiole explants (40%) cultured on the same medium produced 2–4 shoots per explant from the distal portion. The cut portions of the cotyledonary leaf proximal portions responded well to shoot bud formation in the presence of 22.20 µM BA and 14.68 µM phenyl acetic acid (PAA), wherein 100% of explants responded in terms of shoot bud formation, with an average of 10?±?1.7 and 8?±?1.9 shoot buds per explant in KT-OC and BOX-RUB varieties, respectively. The differentiated shoots grew well and proliferated in the presence of 14.68 µM PAA?+?22.20 µM BA and 10 µM AgNO₃. Shoot elongation was obtained in presence of 1.44 µM gibberellic acid (GA₃) and 10 µM AgNO₃. These shoots were rooted on plant growth regulator-free half-strength MS medium and upon hardening; field survival rate was 70%. This reproducible regeneration method for C. frutescens, especially the Indian high pungent variety, from proximal portion of cotyledonary leaf and petiole explants, can be used for biotechnological improvement.     

Improved <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation and direct plant regeneration in four cultivars of finger millet (<Emphasis Type="Italic">Eleusine coracana</Emphasis> (L.) Gaertn.)

We have developed an improved Agrobacterium-mediated transformation and rapid regeneration system for four cultivars (‘CO(Ra)-14’, ‘PR-202’, ‘Try-1’ and ‘Paiyur-2’) of finger millet using optimized transformation and direct plant regeneration conditions. The shoot apical meristems (SAMs) were used as explants in this study. Agrobacterium strain EHA105 carrying binary vector pCAMBIA1301 was used to optimize the transformation conditions. Concentration of hygromycin, the optical density of the culture, infection time, age of the explants, co-cultivation period, the concentrations of acetosyringone and antibiotics were optimized to improve the transformation frequency. The highest frequency of mean transient gus expression (85.1%) was achieved in cultivar ‘CO(Ra)-14’. The entire transformation procedure, from initiating SAMs to planting putative transgenic plantlets in the greenhouse, was completed within 45 days with the highest stable transformation frequency of 11.8% for ‘CO(Ra)-14’. PCR, gus staining and Southern blot analyses were performed in T₀ and T₁ generations to confirm the gene integration. Six events from T₀ had a single copy of the transgene and showed a normal Mendelian pattern of segregation. To our knowledge, this is the first report on the high frequency transformation of finger millet by Agrobacterium and subsequent recovery of transgenic plants via direct plant regeneration without a callus phase, in short duration (45 days). The proposed protocol could be supportive in breaking through the bottleneck in transformation and regeneration of finger millet cultivars.     

Mechanisms of action of plant growth promoting bacteria

The idea of eliminating the use of fertilizers which are sometimes environmentally unsafe is slowly becoming a reality because of the emergence of microorganisms that can serve the same purpose or even do better. Depletion of soil nutrients through leaching into the waterways and causing contamination are some of the negative effects of these chemical fertilizers that prompted the need for suitable alternatives. This brings us to the idea of using microbes that can be developed for use as biological fertilizers (biofertilizers). They are environmentally friendly as they are natural living organisms. They increase crop yield and production and, in addition, in developing countries, they are less expensive compared to chemical fertilizers. These biofertilizers are typically called plant growth-promoting bacteria (PGPB). In addition to PGPB, some fungi have also been demonstrated to promote plant growth. Apart from improving crop yields, some biofertilizers also control various plant pathogens. The objective of worldwide sustainable agriculture is much more likely to be achieved through the widespread use of biofertilizers rather than chemically synthesized fertilizers. However, to realize this objective it is essential that the many mechanisms employed by PGPB first be thoroughly understood thereby allowing workers to fully harness the potentials of these microbes. The present state of our knowledge regarding the fundamental mechanisms employed by PGPB is discussed herein.     

Recent advances in production of 5-aminolevulinic acid using biological strategies

5-Aminolevulinic acid (5-ALA) is the precursor for the biosynthesis of tetrapyrrole compounds and has broad applications in the medical and agricultural fields. Because of the disadvantages of chemical synthesis methods, microbial production of 5-ALA has drawn intensive attention and has been regarded as an alternative in the last years, especially with the rapid development of metabolic engineering and synthetic biology. In this mini-review, recent advances on the application and microbial production of 5-ALA using novel biological approaches (such as whole-cell enzymatic-transformation, metabolic pathway engineering and cell-free process) are described and discussed in detail. In addition, the challenges and prospects of synthetic biology are discussed.     

Climate warming and atmospheric deposition affect seed viability of common juniper (<Emphasis Type="Italic">Juniperus communis</Emphasis>) via their impact on the nutrient status of the plant

Global environmental change is increasingly affecting species worldwide. One of the emblematic casualties among plants in several European countries is common juniper (Juniperus communis). Many populations of common juniper throughout its distribution range are declining. The relative lack of viable seed production, resulting in low probabilities for successful natural regeneration, is one of the main reasons for this decline. Climate warming and elevated atmospheric depositions have been shown to negatively affect seed viability of common juniper, but our understanding of the underlying mechanisms remains scarce. One possible pathway is via changes in the plant nutrient status that, in turn, may affect seed viability. Here we took advantage of large-scale gradients in climate and atmospheric depositions between central Sweden and northern Spain, and analysed foliar nutrient concentrations and stoichiometry and seed viability in 20 juniper populations spread across Europe. Our results show that increasing temperatures can negatively affect needle N and P concentrations while enhanced potentially acidifying depositions resulted in lower foliar N and Ca concentrations. Needle C:N ratios increased with higher temperature, acidifying depositions and precipitation. By linking these patterns to seed viability, we found that low needle P, Ca and Mg concentrations were related to low seed viability. Thus, a shortage of these key elements during seed development and seed nutrient storage, can lead to anomalies and seed abortion. These findings help to explain the low seed viability of juniper in Europe and may help to assist land managers to take urgently needed conservation actions.