Analysis of trace elements in animal tissues

Graphite furnace atomic absorption spectrophotometry is a method used for the measurement of low concentrations of manganese (ppb range). Despite the widespread use of this technique, there is considerable inconsistency concerning sample preparation and choice of instrumental parameters. In this paper, we determined manganese concentrations of National Bureau of Standards (NBS) bovine liver by both graphite furnace (Instrumentation Laboratory IL 555B) and flame atomic absorption following wet digestion of the sample with nitric acid. The following instrumental parameters for the graphite furnace were found optimal for the measurement of manganese in digested NBS bovine liver: inert gas flow=14 SCFH, drying temperature 100°C/15 s (step 1), 125°C/15 s (step 2), pyrolysis temperature 500°C/15 s (step 3), and 1000°C/15 s (step 4); atomization temperature 2250°C/10 s (step 5). For optimal results, the nitric acid concentration of the sample should be between 2 and 4M. There were no significant differences found for manganese concentrations determined by either peak height or peak area measurement. Additionally, no significant differences were found in manganese concentrations determined by flame or furnace methods. Assuming proper sample preparation and choice of instrumental parameters, values obtained for manganese concentration by graphite furnace and flame atomic absorption spectrophotometry are similar. Therefore, data obtained by these two methods can be compared directly.     

A light and electron microscope study of changes occurring at the cut ends following section of the dorsal roots of rat spinal nerves

Summary Rat dorsal spinal nerve roots were cut; 20 h later the axons in the vicinity of the cut were examined by light and electron microscopy. The changes in the cut tip distant from the ganglion were largely degenerative. On the ganglionic side of the cut a cap of free unmyelinated sprouts was formed. These sprouts contained clear and dense-core vesicles 40–150 nm in diameter, smooth endoplasmic reticulum and mitochondria. Some of the unmyelinated sprouts were extensions of myelinated axons, others arose from myelinated axons by lateral budding. In both myelinated and non-myelinated axons there was an accumulation of mitochondria, tubulo-vesicular smooth endoplasmic reticulum and large and small dense-core vesicles for a distance of approximately 500 m behind the tip. Dense-core vesicles were more common in nonmyelinated axons than in their myelinated counterparts. In areas of intense accumulation the non-myelinated fibres were grossly swollen and distorted. The myelinated axons and some of the sprouts contained an unusual type of mitochondrion. The similarity between these sprouts and pre-synaptic terminals is discussed.I.R.D. is supported by the Medical Research Council; P.K. thanks the Mental Health Trust for a project grant     

In vitro construction of bacteriophage λ and plasmid DNA molecules containing DNA fragments from bacteriophage T4

Restriction endonucleases EcoRI and HindIII generated fragments of T4 cytosine-containing DNA were inserted into bacteriophage vector λgtSu_III and plasmid vectors pMB9 and pBR313. Resulting clones were screened for hybridization with ³²P labeled T4 tRNA. Recombinant bacteriophages and plasmids were isolated which contained a T4 fragment coding for T4 RNA species 1 and 2 and T4 tRNA^Arg. Selected λ-T4 hybrid bacteriophages were grown to high titer and their DNA analyzed by gel electrophoresis.     

Linking behavioral states to landscape features for improved conservation management

1. A central theme for conservation is understanding how animals differentially use, and are affected by change in, the landscapes they inhabit. However, it has been challenging to develop conservation schemes for habitat‐specific behaviors.
2. Here we use behavioral change point analysis to identify behavioral states of golden eagles (Aquila chrysaetos) in the Sonoran and Mojave Deserts of the southwestern United States, and we identify, for each behavioral state, conservation‐relevant habitat associations.
3. We modeled behavior using 186,859 GPS points from 48 eagles and identified 2,851 distinct segments comprising four behavioral states. Altitude above ground level (AGL) best differentiated behavioral states, with two clusters of short‐distance movement behaviors characterized by low AGL (state 1 AGL = 14 m (median); state 2 AGL = 11 m) and two associated with longer‐distance movement behaviors and characterized by higher AGL (state 3 AGL = 108 m; state 4 AGL = 450 m).
4. Behaviors such as perching and low‐altitude hunting were associated with short‐distance movements in updraft‐poor environments, at higher elevations, and over steeper and more north‐facing terrain. In contrast, medium‐distance movements such as hunting and transiting were over gentle and south‐facing slopes. Long‐distance transiting occurred over the desert habitats that generate the best updraft.
5. This information can guide management of this species, and our approach provides a template for behavior‐specific habitat associations for other species of management concern.

     

Osmotic stress induces gut microbiota community shift in fish

Alteration of the gut microbiota plays an important role in animal health and metabolic diseases. However, little is known with respect to the influence of environmental osmolality on the gut microbial community. The aim of the current study was to determine whether the reduction in salinity affects the gut microbiota and identify its potential role in salinity acclimation. Using Oryzias melastigma as a model organism to perform progressive hypotonic transfer experiments, we evaluated three conditions: seawater control (SW), SW to 50% sea water transfer (SFW) and SW to SFW to freshwater transfer (FW). Our results showed that the SFW and FW transfer groups contained higher operational taxonomic unit microbiota diversities. The dominant bacteria in all conditions constituted the phylum Proteobacteria, with the majority in the SW and SFW transfer gut comprising Vibrio at the genus level, whereas this population was replaced by Pseudomonas in the FW transfer gut. Furthermore, our data revealed that the FW transfer gut microbiota exhibited a reduced renin–angiotensin system, which is important in SW acclimation. In addition, induced detoxification and immune mechanisms were found in the FW transfer gut microbiota. The shift of the bacteria community in different osmolality environments indicated possible roles of bacteria in facilitating host acclimation.     

Fungal functional ecology: bringing a trait‐based approach to plant‐associated fungi

Fungi play many essential roles in ecosystems. They facilitate plant access to nutrients and water, serve as decay agents that cycle carbon and nutrients through the soil, water and atmosphere, and are major regulators of macro‐organismal populations. Although technological advances are improving the detection and identification of fungi, there still exist key gaps in our ecological knowledge of this kingdom, especially related to function . Trait‐based approaches have been instrumental in strengthening our understanding of plant functional ecology and, as such, provide excellent models for deepening our understanding of fungal functional ecology in ways that complement insights gained from traditional and ‐omics‐based techniques. In this review, we synthesize current knowledge of fungal functional ecology, taxonomy and systematics and introduce a novel database of fungal functional traits (Fun^Fun). Fun^Fun is built to interface with other databases to explore and predict how fungal functional diversity varies by taxonomy, guild, and other evolutionary or ecological grouping variables. To highlight how a quantitative trait‐based approach can provide new insights, we describe multiple targeted examples and end by suggesting next steps in the rapidly growing field of fungal functional ecology.     

Fine‐scale habitat selection by sympatric Canada lynx and bobcat

The Canada lynx (Lynx canadensis) and the bobcat (Lynx rufus) are closely related species with overlap at their range peripheries, but the factors that limit each species and the interactions between them are not well understood. Habitat selection is a hierarchical process, in which selection at higher orders (geographic range, home range) may constrain selection at lower orders (within the home range). Habitat selection at a very fine scale within the home range has been less studied for both lynx and bobcat compared to selection at broader spatiotemporal scales. To compare this fourth‐order habitat selection by the two species in an area of sympatry, we tracked lynx and bobcat during the winters of 2017 and 2018 on the north shore of Lake Huron, Ontario. We found that both lynx and bobcat selected shallower snow, higher snowshoe hare abundance, and higher amounts of coniferous forest at the fourth order. However, the two species were spatially segregated at the second order, and lynx were found in areas with deeper snow, more snowshoe hare, and more coniferous forest. Taken together, our findings demonstrate that the lynx and bobcat select different resources at the second order, assorting along an environmental gradient in the study area, and that competition is unlikely to be occurring between the two species at finer scales.