Effects of Inoculum Additions in the Presence of a Preestablished Arbuscular Mycorrhizal Fungal Community

Communities of arbuscular mycorrhizal fungi (AMF) are crucial for promoting plant productivity in most terrestrial systems, including anthropogenically managed ecosystems. Application of AMF inocula has therefore become a widespread practice. It is, however, pertinent to understand the mechanisms that govern AMF community composition and their performance in order to design successful manipulations. Here we assess whether the composition and plant growth-promotional effects of a synthetic AMF community can be altered by inoculum additions of the isolates forming the community. This was determined by following the effects of three AMF isolates, each inoculated in two propagule densities into a preestablished AMF community. Fungal abundance in roots and plant growth were evaluated in three sequential harvests. We found a transient positive response in AMF abundance to the intraspecific inoculation only in the competitively weakest isolate. The other two isolates responded negatively to intra- and interspecific inoculations, and in some cases plant growth was also reduced. Our results suggest that increasing the AMF density may lead to increased competition among fungi and a trade-off with their ability to promote plant productivity. This is a key ecological aspect to consider when introducing AMF into soils.     

Potential of Nociceptin/Orphanin FQ Peptide Analogs for Drug Development

Nociceptin receptor (NOP) belongs to the family of opioid receptors but was discovered and characterized much later than the so called classical opioid receptors, μ, δ and κ (or MOP, DOP and KOP, resp.). Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand of this receptor and it controls numerous important functions in the central nervous system and in the periphery, so its analogs may be developed as innovative drugs for the treatment of a variety of conditions and pathological states. Availability of potent and selective ligands with high affinity to NOP receptor is essential to fully understand the role of NOP-N/OFQ system in the body, which in turn may lead to designing novel therapeutics. Here, we have focused on reviewing the structure of potent peptide-based agonists, antagonists, biased analogs and bivalent ligands that target NOP receptor.     

The in vitro effect of progesterone on the orexin system in porcine uterine tissues during early pregnancy

Background

Orexin A (OXA) and orexin B (OXB) are hypothalamic-derived peptides that participate in the regulation of energy metabolism, food intake and reproductive function by influencing the hypothalamic-pituitary-ovarian axis. Orexins are also produced in the endometrium, myometrium and placenta, which suggests that they could act as a link between energy metabolism and the reproductive system. Changes in the expression of orexin and the orexin receptor genes and proteins during the oestrous cycle and early gestation in pigs imply that orexin activity may be regulated by local factors within the uterus. The aim of this study was to investigate the influence of progesterone (P₄) on the expression of orexin system genes, and proteins in the porcine uterus during early gestation. Gene expression was analyzed by real-time PCR. Adiponectin secretion was determined by ELISA, and the receptors proteins content was defined using western blot analysis.

Results

In the endometrium, P₄ enhanced OXA secretion on days 10 to 11 of gestation and OXB secretion on days 12 to 13. In the myometrium, P₄ inhibited the secretion of both orexins on days 15 to 16 and OXB secretion also on days 12 to 13. In the endometrium, P₄ inhibited the expression of orexin receptor 1 (OX1R) protein at nearly all times analyzed, whereas the expression of orexin receptor 2 (OX2R) protein was inhibited only on days 15 to 16 of gestation. In the myometrium, P₄ stimulated OX1R protein expression on days 12 to 13 and 15 to 16 of gestation and inhibited OX1R protein expression on days 27 to 28. The expression of OX2R protein in the myometrium increased on days 12 to 13 and decreased on days 10 to 11 and 15 to 16.

Conclusions

The results indicate that P₄ could regulate the expression of the orexin system in the porcine uterus during early pregnancy, which suggests the presence of a local feedback loop that could play an important role in the regulation of maternal metabolism during pregnancy. The findings may contribute to the existing knowledge of the mechanisms linking maternal energy metabolism with the regulation of the reproductive system during pregnancy.

     

The microenvironment of naked mole‐rat burrows in East Africa

Naked mole‐rats (Heterocephalus glaber) can be extremely long‐lived and are resistant to cancer. Hence, they have been proposed as a model organism for delayed ageing. Adaptation to a constant hypoxic and hypercapnic environment has been suggested as reason for their apparent ability to tolerate oxidative stress. Nevertheless, little is known about the natural habitat to which the species evolved. Naked mole‐rat burrow environments were assessed in Ethiopia and Kenya. Despite reported thermolability of naked mole‐rats, skin temperature upon capture varied (23.7–35.4°C), mostly within the species’ thermoneutral zone, demonstrating their ability to maintain homoiothermy even under wide fluctuations of burrow temperature (24.6–48.8°C) and humidity (31.2%–92.8%), which are far greater than previously reported. Burrow temperature regularly alternates during the daytime and night‐time, driving convective currents that circulate air in the tunnels. Consequently, concentrations of CO₂ and O₂ in burrows only slightly deviated from surface atmosphere. This contradicts the assumption of constant hypoxia/hypercapnia in subterranean burrows. In addition to diffusion, animal movement and occasional wind‐driven ventilation, our data support the temperature‐driven convective model of circulation. The naked mole‐rat burrow is a relatively normoxic subterranean microenvironment with considerable fluctuations in temperature and humidity.     

Improved high-performance liquid chromatographic method for N-acetylgalactosamine-4-sulfate sulfatase (arylsulfatase B) activity determination using uridine diphosho-N-acetylgalactosamine-4-sulfate

UDP-N-acetylgalactosamine-4-sulfate (UDP-GalNAc-4-S) was isolated from hen oviduct (isthmus) with a yield of 31 μmol per 100 g of wet tissue and used for arylsulfatase B (ASB) activity determination. Two HPLC methods of separation and quantitation of the reaction product were described: (1) an original gradient elution method which makes it possible to determine the reaction product when only partially purified ASB was used and additional uridine derivatives were formed during incubation: (2) an improved, fast isocratic elution method which may be used in the case of purified ASB preparations, devoid of other nucleotide hydrolysing enzymes. For both methods the detection limit was 0.1 nmol of product with standard error of determination ?3%. Using the gradient elution method we have found that UDP-GalNAc-4-S was hydrolysed by bovine arylsulfatase B1 most efficiently at pH 5.0 and concentration 0.5 mM with K_m=85 μM.     

PHYLOGENY OF THE CONJUGATING GREEN ALGAE (ZYGNEMOPHYCEAE) BASED ON rbc L SEQUENCES

Sequences of the gene encoding the large subunit of RUBISCO (rbcL) for 30 genera in the six currently recognized families of conjugating green algae (Desmidiaceae, Gonatozygaceae, Mesotaeniaceae, Peniaceae, and Zygnemataceae) were analyzed using maximum parsimony and maximum likelihood; bootstrap replications were performed as a measure of support for clades. Other Charophyceae sensu Mattox and Stewart and representative land plants were used as outgroups. All analyses supported the monophyly of the conjugating green algae. The Desmidiales, or placoderm desmids, constitute a monophyletic group, with moderate to strong support for the four component families of this assemblage (Closteriaceae, Desmidiaceae, Gonatozygaceae, and Peniaceae). The analyses showed that the two families of Zygnematales (Mesotaeniaceae, Zygnemataceae), which have plesiomorphic, unornamented and unsegmented cell walls, are not monophyletic. However, combined taxa of these two traditional families may constitute a monophyletic group. Partitioning the data by codon position revealed no significant differences across all positions or between partitions of positions one and two versus position three. The trees resulting from parsimony analyses using first plus second positions versus third position differed only in topology of branches with poor bootstrap support. The tree derived from third positions only was more resolved than the tree derived from first and second positions. The rbcL‐based phylogeny is largely congruent with published analyses of small subunit rDNA sequences for the Zygnematales. The molecular data do not support hypotheses of monophyly for groups of extant unicellular and filamentous or colonial desmid genera exhibiting a common cell shape. A trend is evident from simple omniradiate cell shapes to taxa with lobed cell and plastid shapes, which supports the hypothesis that chloroplast shape evolved generally from simple to complex. The data imply that multicellular placoderm desmids are monophyletic. Several anomalous placements of genera were found, including the saccoderm desmid Roya in the Gonatozygaceae and the zygnematacean Entransia in the Coleochaetales. The former is strongly supported, although the latter is not, and Entransia's phylogenetic position warrants further study.     

PHYLOGENY OF THE BASAL LINEAGES OF STREPTOPHYTA BASED ON RBCL AND ATPB GENE SEQUENCE DATA

The streptophytes comprise the Charophyceae sensu Mattox and Stewart (a morphologically diverse group of fresh‐water green algae) and the embryophytes (land plants). Several charophycean groups are currently recognized. These include the Charales, Coleochaetales, Chlorokybales, Klebsormidiales and Zygnemophyceae (Desmidiales and Zygnematales). Recently, SSU rRNA gene sequence data allied Mesostigma viride (Prasinophyceae) with the Streptophyta. Complete chloroplast sequence data, however, placed Mesostigma sister to all green algae, not with the streptophytes. Several morphological, ultrastructural and biochemical features unite these lineages into a monophyletic group including embryophytes, but evolutionary relationships among the basal streptophytes remain ambiguous. To date, numerous studies using SSU rRNA gene sequences have yielded differing phylogenies with varying degrees of support dependent upon taxon sampling and choice of phylogenetic method. Like SSU data, chloroplast DNA sequence data have been used to examine relationships within the Charales, Coleochaetales, Zygnemophyceae and embryophytes. Representatives of all basal streptophyte lineages have not been examined using chloroplast data in a single analysis. Phylogenetic analyses were performed using DNA sequences of rbcL (the genes encoding the large subunit of rubisco) and atpB (the beta‐subunit of ATPase) to examine relationships of basal streptophyte lineages. Preliminary analyses placed the branch leading to Mesostigma as the basal lineage in the Streptophyta with Chlorokybus, the sole representative of the Chlorokybales, branching next. Klebsormidiales and the enigmatic genus Entransia were sister taxa. Sister to these, the Charales, Coleochaetales, embryophytes and Zygnemophyceae formed a monophyletic group with Charales and Coleochaetales sister to each other and this clade sister to the embryophytes.