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.     

Isolation of lactoperoxidase, lactoferrin, α-lactalbumin, β-lactoglobulin B and β-lactoglobulin A from bovine rennet whey using ion exchange chromatography

A mild and rapid method is described for isolating various milk proteins from bovine rennet whey. β-Lactoglobulin from bovine rennet whey was easily adsorbed on and desorbed from a weak anion exchanger, diethylaminoethyl-Toyopearl. However, α-lactalbumin could not be adsorbed onto the resin. α-Lactalbumin and β-lactoglobulin from rennet whey could also be adsorbed and separated using a strong anion exchanger, quaternary aminoethyl-Toyopearl. The rennet whey was passed through a strong cation exchanger, sulphopropyl-Toyopearl, to separate lactoperoxidase and lactoferrin. α-Lactalbumin and β-lactoglobulin were adsorbed onto quaternary aminoethyl-Toyopearl. α-Lactalbumin was eluted using a linear (0–0.15 M) concentration gradient of NaCl in 0.05 M Tris–HCl buffer (pH 8.5). Subsequently, β-lactoglobulin B and β-lactoglobulin A were eluted from the column with 0.05 M Tris–HCl (pH 6.8), using a linear (0.1–0.25 M) concentration gradient of NaCl. The yields were 1260 mg α-lactalbumin, 1290 mg β-lactoglobulin B and 2280 mg β-lactoglobulin A from 1 l rennet whey.     

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.     

Repeated pre-training sleep restriction in adolescent rats impaired spatial performance

Sleep and Biological Rhythms - Chronic sleep deprivation (SD) is an overwhelming problem in young students. Firstly, we investigated whether different levels of pre-training SD had effects on...     

Dynamics of macrozoobenthos productivity characteristics on shelves of the Far Eastern seas in the 2000s

The trophic structure of benthic communities in the Sea of Okhotsk and Bering Sea was analyzed based on the results of macrobenthic survey catches conducted in the Far Eastern seas in the 2000s. The production of trophic levels and entire communities was determined. It was shown that production of benthic communities is still at a high level and has almost not changed since the 1980s. The arrangement of the communities of some shelf areas by productivity characteristics was made.     

Margination and adhesion dynamics of tumor cells in a real microvascular network

In tumor metastasis, the margination and adhesion of tumor cells are two critical and closely related steps, which may determine the destination where the tumor cells extravasate to. We performed a direct three-dimensional simulation on the behaviors of the tumor cells in a real microvascular network, by a hybrid method of the smoothed dissipative particle dynamics and immersed boundary method (SDPD-IBM). The tumor cells are found to adhere at the microvascular bifurcations more frequently, and there is a positive correlation between the adhesion of the tumor cells and the wall-directed force from the surrounding red blood cells (RBCs). The larger the wall-directed force is, the closer the tumor cells are marginated towards the wall, and the higher the probability of adhesion behavior happen is. A relatively low or high hematocrit can help to prevent the adhesion of tumor cells, and similarly, increasing the shear rate of blood flow can serve the same purpose. These results suggest that the tumor cells may be more likely to extravasate at the microvascular bifurcations if the blood flow is slow and the hematocrit is moderate.     

A yeast's eye view of mammalian reproduction: cross-species gene co-expression in meiotic prophase

Background  

Meiotic prophase is a critical stage in sexual reproduction. Aberrant chromosome recombination during this stage is a leading cause of human miscarriages and birth defects. However, due to the experimental intractability of mammalian gonads, only a very limited number of meiotic genes have been characterized. Here we aim to identify novel meiotic genes important in human reproduction through computational mining of cross-species and cross-sex time-series expression data from budding yeast, mouse postnatal testis, mouse embryonic ovary, and human fetal ovary.