Responses of sympatric canids to human development revealed through citizen science

Measuring wildlife responses to anthropogenic activities often requires long‐term, large‐scale datasets that are difficult to collect. This is particularly true for rare or cryptic species, which includes many mammalian carnivores. Citizen science, in which members of the public participate in scientific work, can facilitate collection of large datasets while increasing public awareness of wildlife research and conservation. Hunters provide unique benefits for citizen science given their knowledge and interest in outdoor activities. We examined how anthropogenic changes to land cover impacted relative abundance of two sympatric canids, coyote (Canis latrans), and red fox (Vulpes vulpes) at a large spatial scale. In order to assess how land cover affected canids at this scale, we used citizen science data from bow hunter sighting logs collected throughout New York State, USA, during 2004–2017. We found that the two species had contrasting responses to development, with red foxes positively correlated and coyotes negatively correlated with the percentage of low‐density development. Red foxes also responded positively to agriculture, but less so when agricultural habitat was fragmented. Agriculture provides food and denning resources for red foxes, whereas coyotes may select forested areas for denning. Though coyotes and red foxes compete in areas of sympatry, we did not find a relationship between species abundance, likely a consequence of the coarse spatial resolution used. Red foxes may be able to coexist with coyotes by altering their diets and habitat use, or by maintaining territories in small areas between coyote territories. Our study shows the value of citizen science, and particularly hunters, in collection of long‐term data across large areas (i.e., the entire state of New York) that otherwise would unlikely be obtained.     

Dual peptidergic innervation of the blowfly hindgut: a light- and electron microscopic study of FMRFamide and proctolin immunoreactive fibers.

1. The innervation of the hindgut, rectal valve, rectum and rectal papillae of the adult blowfly, Calliphora erythrocephala, was studied by means of light and electron microscopic immunocytochemistry, using antibodies against the neuropeptides proctolin and FMRFamide. 2. Branches from the abdominal nerves reaching the posterior portion of the gut were found to contain mostly neurosecretory type axons and to innervate the muscle coat of all hindgut structures studied. 3. Some of the axons found in these nerve branches innervating the gut display proctolin- others FMRFamide-like immunoreactivity. Both types of peptidergic axons were found to have abundant terminals in the muscle coat of the hindgut, rectum and rectal valve and in the medulla of the rectal papillae. 4. It is clear that two separate peptidergic systems derived from the abdominal ganglion are supplying the hindgut structures, and, possibly, they use proctolin- and FMRFamide-like peptides respectively as their transmitters or modulators.     

Glucose-signalled inhibition of cysteine-proteases involved in nitrate reductase degradation in oat leaf segments

Regulation of nitrate reductase (NR; EC 1.6.6.1) breakdown, measured as loss of maximal activity (MNRA), was studied in leaf segments of 7-day-old oat plants in the light for up to 4 h. In segments floating on 1 mM tungstate, NR lost more than 40% of its initial maximal activity. Cycloheximide, high (300 mM) glucose (Glc) and inhibitors of cysteine proteases stabilized NR in situ , suggesting that MNRA decrease was due to the hydrolysis of NR by a short-lived, glucose-modulated cysteine protease. Loss of MNRA was accelerated by cantharidin (CTHR) and inhibited by staurosporine, suggesting that NR breakdown required continuous phosphorylation. High glucose inhibited any further MNRA decrease when supplied after a 30-min pretreatment with CTHR, suggesting that a phosphorylated protein was its target. Isoosmolar polyethylene glycol also stabilized NR but not in the presence of CTHR. Low (30 mM) Glc stabilized NR only in the presence of Ca²⁺, and CTHR inhibited its effect. EGTA and LaCl₃ completely arrested the effects of both high- and low- Glc. Like low D-Glc, low L-Glc (glucose analog not transported) inhibited NR breakdown in the presence of Ca²⁺, but at high concentration only 2-deoxyglucose, that is phosphorylated but not further metabolized, and glucose-6P were effective in the presence of CTHR, suggesting that receptors for high- and low- Glc were located in different cell compartments. It is proposed that high- and low- Glc trigger different signalling pathways, with calcium as a common upstream secondary messenger and protein kinases and protein phosphatases being downstream components in the cascade of reactions that modulates NR proteolysis.     

Tolerance of DNA Mismatches in Dmc1 Recombinase-mediated DNA Strand Exchange

Recombination between homologous chromosomes is required for the faithful meiotic segregation of chromosomes and leads to the generation of genetic diversity. The conserved meiosis-specific Dmc1 recombinase catalyzes homologous recombination triggered by DNA double strand breaks through the exchange of parental DNA sequences. Although providing an efficient rate of DNA strand exchange between polymorphic alleles, Dmc1 must also guard against recombination between divergent sequences. How DNA mismatches affect Dmc1-mediated DNA strand exchange is not understood. We have used fluorescence resonance energy transfer to study the mechanism of Dmc1-mediated strand exchange between DNA oligonucleotides with different degrees of heterology. The efficiency of strand exchange is highly sensitive to the location, type, and distribution of mismatches. Mismatches near the 3′ end of the initiating DNA strand have a small effect, whereas most mismatches near the 5′ end impede strand exchange dramatically. The Hop2-Mnd1 protein complex stimulates Dmc1-catalyzed strand exchange on homologous DNA or containing a single mismatch. We observed that Dmc1 can reject divergent DNA sequences while bypassing a few mismatches in the DNA sequence. Our findings have important implications in understanding meiotic recombination. First, Dmc1 acts as an initial barrier for heterologous recombination, with the mismatch repair system providing a second level of proofreading, to ensure that ectopic sequences are not recombined. Second, Dmc1 stepping over infrequent mismatches is likely critical for allowing recombination between the polymorphic sequences of homologous chromosomes, thus contributing to gene conversion and genetic diversity.     

Differential strategies of two species of arbuscular mycorrhizal fungi in the protection of maize plants grown in chromium-contaminated soils

Chromium (Cr) is a nonessential element for plants that is extremely toxic at high concentrations. Zea mays L. is a species of plant that has developed adaptive mechanisms to increase its tolerance and absorption capacity for this metal. One effective mechanism is to form associations with arbuscular mycorrhizal fungi (AMF), which help the plant cope with stress from heavy metals such as Cr. However, it is still not clear which species of AMF are more efficient as bioremediating agents for plants of agricultural importance. Here, we evaluated the effect of Gigaspora gigantea and Rhizophagus irregularis as protective agents of maize plants in soils contaminated with Cr at concentrations of 0, 48.5, 97 and 194 mg kg^?1 under greenhouse conditions. Maize tolerance to Cr was corroborated, as well as increased absorption of this element by plants associated with both species of AMF. G. gigantea caused an increase in nitrogen content and greater translocation of Cr to the aerial part of the plant; R. irregularis registered an increase in the formation of arbuscules and vesicles with increasing metal concentration and greater retention of Cr in the roots of the plants. Based on these results, we can conclude that the analyzed species of fungi use different strategies, with similar effectiveness, to enhance the absorption capacity of Cr by the plant and influence the differential deposition of this metal in various parts of the plant.

     

Engineering Native and Synthetic Pathways in Pseudomonas putida for the Production of Tailored Polyhydroxyalkanoates

Growing environmental concern sparks renewed interest in the sustainable production of (bio)materials that can replace oil-derived goods. Polyhydroxyalkanoates (PHAs) are isotactic polymers that play a critical role in the central metabolism of producer bacteria, as they act as dynamic reservoirs of carbon and reducing equivalents. PHAs continue to attract industrial attention as a starting point toward renewable, biodegradable, biocompatible, and versatile thermoplastic and elastomeric materials. Pseudomonas species have been known for long as efficient biopolymer producers, especially for medium-chain-length PHAs. The surge of synthetic biology and metabolic engineering approaches in recent years offers the possibility of exploiting the untapped potential of Pseudomonas cell factories for the production of tailored PHAs. In this article, an overview of the metabolic and regulatory circuits that rule PHA accumulation in Pseudomonas putida is provided, and approaches leading to the biosynthesis of novel polymers (e.g., PHAs including nonbiological chemical elements in their structures) are discussed. The potential of novel PHAs to disrupt existing and future market segments is closer to realization than ever before. The review is concluded by pinpointing challenges that currently hinder the wide adoption of bio-based PHAs, and strategies toward programmable polymer biosynthesis from alternative substrates in engineered P. putida strains are proposed.