The role of epiphytism in architecture and evolutionary constraint within mycorrhizal networks of tropical orchids

Characterizing the architecture of bipartite networks is increasingly used as a framework to study biotic interactions within their ecological context and to assess the extent to which evolutionary constraint shape them. Orchid mycorrhizal symbioses are particularly interesting as they are viewed as more beneficial for plants than for fungi, a situation expected to result in an asymmetry of biological constraint. This study addressed the architecture and phylogenetic constraint in these associations in tropical context. We identified a bipartite network including 73 orchid species and 95 taxonomic units of mycorrhizal fungi across the natural habitats of Reunion Island. Unlike some recent evidence for nestedness in mycorrhizal symbioses, we found a highly modular architecture that largely reflected an ecological barrier between epiphytic and terrestrial subnetworks. By testing for phylogenetic signal, the overall signal was stronger for both partners in the epiphytic subnetwork. Moreover, in the subnetwork of epiphytic angraecoid orchids, the signal in orchid phylogeny was stronger than the signal in fungal phylogeny. Epiphytic associations are therefore more conservative and may co‐evolve more than terrestrial ones. We suggest that such tighter phylogenetic specialization may have been driven by stressful life conditions in the epiphytic niches. In addition to paralleling recent insights into mycorrhizal networks, this study furthermore provides support for epiphytism as a major factor affecting ecological assemblage and evolutionary constraint in tropical mycorrhizal symbioses.     

The mitochondrial and nuclear genetic structure of Myotis capaccinii (Chiroptera: Vespertilionidae) in the Eurasian transition, and its taxonomic implications

Allopatric isolation in glacial refugia has caused differentiation and speciation in many taxa globally. In this study, we investigated the nuclear and mitochondrial genetic differentiation of the long fingered bat, Myotis capaccinii during the ice ages in south-eastern Europe and Anatolia. The mitochondrial DNA (mtDNA) analyses indicated a suture zone similar to those recorded in other animal species, including bats, suggesting the association of more than one refugium with the region. Contrary to most of the other species where a suture zone was seen in Anatolia, for M. capaccinii the geographical location of the genetic break was in south-eastern Europe. This mitochondrial differentiation was not reflected in the nuclear microsatellites, however, suggesting that the lack of contact during the ice ages did not result in reproductive isolation. Hence taxonomically, the two mitochondrial clades cannot be treated as separate species.     

Metabolome and water status phenotyping of Arabidopsis under abiotic stress cues reveals new insight into ESK1 function

Metabolomic investigation of the freezing-tolerant Arabidopsis mutant esk1 revealed large alterations in polar metabolite content in roots and shoots. Stress metabolic markers were found to be among the most significant metabolic markers associated with the mutation, but also compounds related to growth regulation or nutrition. The metabolic phenotype of esk1 was also compared to that of wild type (WT) under various environmental constraints, namely cold, salinity and dehydration. The mutant was shown to express constitutively a subset of metabolic responses which fits with the core of stress metabolic responses in the WT. But remarkably, the most specific metabolic responses to cold acclimation were not phenocopied by esk1 mutation and remained fully inducible in the mutant at low temperature. Under salt stress, esk1 accumulated lower amounts of Na⁺ in leaves than the WT, and under dehydration stress its metabolic profile and osmotic potential were only slightly impacted. These phenotypes are consistent with the hypothesis of an altered water status in esk1 , which actually exhibited basic lower water content (WC) and transpiration rate (TR) than the WT. Taken together, the results suggest that ESK1 does not function as a specific cold acclimation gene, but could rather be involved in water homeostasis.     

Additional Nucleotide Sequences in Precursor 16S Ribosomal RNA from <Emphasis Type="Italic">Escherichia coli</Emphasis>

MATURE 5S, 16S and 23S ribosomal RNA species present in E. coli ribosomes are the end products of complex biosyn-thetic pathways. They are formed by reduction in length, and methylation of longer RNA chains transcribed on the ribosomal RNA cistrons of E. coli DNA. While these modifications take place the ribosome structure is formed by progressive addition of ribosomal proteins and conformational changes in the resulting ribonucleoprotein precursor particles¹.     

Breeding biology during establishment of a reintroduced Griffon Vulture Gyps fulvus population

We studied the breeding parameters of a reintroduced population of individually marked Griffon Vultures Gyps fulvus in the Grand Causses region of southern France from the time of first reintroduction in 1982 to 1992. Among nesters, 65% of the birds released as immatures or born in the wild recruited into the breeding population when 4 years old, i.e. 1 year earlier than previously described. The proportion of birds nesting each year was relatively high and increased with time, suggesting that conspecific attraction favoured recruitment. We detected a permanent adverse effect of long-term captivity on the nesting success of birds released when more than 2 years old: compared to the natural population, birds which had been kept in captivity showed a reduced breeding success during the whole study period. The breeding success of released immatures and wild-born birds was similar to the highest values observed in a natural population in the Spanish and French Pyrenees. Breeding failures did not usually result in mate change but affected nest-site fidelity. Birds not born in the wild were more likely to recruit to the largest subcolonies available, which highlights the role of social attraction. The observed philopatry of wild-born birds probably resulted from such a social attraction since most of them were born in the largest subcolony. Conspecific attraction maintained the spatial aggregation of nests, whereas nest changes after a breeding failure favoured the spatial expansion of the colony.     

Molecular phylogeny of the Praomys complex (Rodentia: Murinae): a study based on DNA/DNA hybridization experiments.

Within the Murinae (Muridae: Rodentia), the African rats of the Praomys group, whose systematics has been studied through different approaches, have raised numerous taxonomic problems. Different taxa related to Praomys have successively been described, among which Mastomys, Myomys and Hylomyscus were considered either as separate genera or subgenera of Praomys. In order to clarify the relationships within the Praomys group, we conducted a series of DNA/DNA hybridization experiments involving different species of Praomys, Mastomys, Myomys and Hylomyscus plus other Murinae and a Cricetomyinae. This study indicates that the Praomys complex is a monophyletic entity clearly separated from the other African and Asian Murinae. If Mastomys and Hylomyscus appeared to be independent genera, the taxonomic situation of Praomys and Myomys is more difficult to ascertain. Indeed, Praomys tullbergi appears more closely related to Myomys daltoni than to another species of Praomys , namely P. jacksoni , suggesting paraphyly for Praomys. Furthermore, P. jacksoni is as distant from P. tullbergi as from any species of Mastomys. Additional species of Praomys and, especially, of Myomys , are needed for reaching a definitive conclusion on these latter taxa. The Praomys group is more related to Mus than to Rattus. To calibrate our molecular distances with geological time, we used a dating of 10 Myr for the Musi Rattus dichotomy. The inferred rate of molecular evolution suggests a dating of c. 8 Myr for the separation of the Praomys group from the Mus lineage.     

The T→C mutation at position +96 of the untranslated region 3′ to the terminating codon of the β-globin gene is a rare polymorphism that does not cause a β-thalassemia as previously ascribed

We have observed a TC mutation at position +96 of the untranslated region 3 to the terminating codon of the -globin gene in members of two Czech families and one black family. Data from initial studies suggested that this change was the cause of a -thalassemia, but continued analyses have provided convincing evidence that this mutation is a simple polymorphism.     

Incidence and genetic diversity of raspberry bushy dwarf virus (RBDV) in Rubus spp. in Turkey

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy.     

Synthesis,Biological Evaluation,and Molecular Modeling Studies of New 1,3,4-Thiadiazole Derivatives as Potent Antimicrobial Agents

In this work, the synthesis, characterization, and biological activities of a new series of 1,3,4-thiadiazole derivatives were investigated. The structures of final compounds were identified using ¹H-NMR, ¹³C-NMR, elemental analysis, and HRMS. All the new synthesized compounds were then screened for their antimicrobial activity against four types of pathogenic bacteria and one fungal strain, by application of the MIC assays, using Ampicilin, Gentamycin, Vancomycin, and Fluconazole as standards. Among the compounds, the MIC values of 4 and 8 μg/mL of the compounds 3f and 3g , respectively, are remarkable and indicate that these compounds are good candidates for antifungal activity. The docking experiments were used to identify the binding forms of produced ligands with sterol 14-demethylase to acquire insight into relevant proteins. The MD performed about 100 ns simulations to validate selected compounds’ theoretical studies. Finally, using density functional theory (DFT) to predict reactivity, the chemical characteristics and quantum factors of synthesized compounds were computed. These results were then correlated with the experimental data. Furthermore, computational estimation was performed to predict the ADME properties of the most active compound 3f .     

HPLC-DAD Analysis and Versatile Bioactivities of Turkish Sunflower Honeys Using Chemometric Approaches

Sunflower honey (SH) is bright yellow, fragrant, pollen-flavoured, slightly herbaceous and has a unique taste. The present research aims to examine the enzyme inhibitory, antioxidant, anti-inflammatory, antimicrobial and anti-quorum sensing activities and phenolic compositions of 30 sunflower honeys (SHs) produced from several regions of Turkey with chemometric study. SAH from Samsun exhibited the best antioxidant activity in β-carotene linoleic acid (IC₅₀: 7.33±0.17 mg/mL) and CUPRAC (A_0.50: 4.94±0.13 mg/mL) assays, anti-urease activity (60.63±0.87 %) and anti-inflammatory activity against COX-1 (73.94±1.08 %) and COX-2 (44.96±0.85 %). SHs exhibited mild antimicrobial activity against the test microorganisms while they showed high quorum sensing inhibition zones measured in the range of 42–52 mm against the CV026 strain. The phenolic composition was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) system and levulinic, gallic, p-hydroxybenzoic, vanillic and p-coumaric acids were identified in all studied SHs. The classification of SHs was performed the using PCA and HCA. This study revealed that phenolic compounds and biological properties are effective in classification of SHs according to their geographical origin. The results suggest that studied SHs could be valued as potential agents with versatile bioactivities in oxidative stress-related disease, microbial infections, inflammation, melanoma, and peptic ulcer.