Rasamsonia emersonii
(previously
Talaromyces emersonii
) is a thermophilic filamentous fungus displaying optimum growth at 45 °C. It has a history of use in commercial food enzyme production. Its ...unfractionated chitinolytic secretome was partially characterised in the early 1990s; however, no individual chitinase from this source has been described in literature previously. This study describes two GH18 chitinases originating from the
R. emersonii
genome, expressed in the methylotrophic yeast
P. pastoris
. Chit1 comprises of a GH18 catalytic domain and Chit2 comprises of a GH18 catalytic domain and a chitin-binding motif at the C-terminal. The chitinases were expressed as glycoproteins. The apparent molecular weight of Chit1 was 35.8–42.1 kDa with a smearing tail associated with glyco-sidechains visible up to 72.2 kDa. This became two bands of 30.8 and 29.0 kDa upon de-glycosylation. The apparent molecular weight of Chit2 was 50.4 kDa, reducing to 48.2 kDa upon de-glycosylation. Both chitinases displayed endo-chitinase and chitobiosidase activity, temperature optima of 50–55 °C and low pH optima (pH 4.5 or lower); Chit1 displayed a pH optimum of 3.5, retaining > 60% maximum activity at pH 2.2, a pH range lower than most enzymes of fungal origin. Chit2 displayed the highest chitin-degrading ability at 3456 µmol/mg on 4-NP-triacetylchitotriose, but lost activity faster than Chit1, which displayed 403 µmol/mg on the same substrate. The predicted
D
values (time required to reduce the enzyme activity to 10% of its original value at 50 °C) were 19.2 and 2.3 days for Chit1 and Chit2, respectively. Thus, Chit1 can be considered one of few hyperthermostable chitinase enzymes described in literature to date. Their physicochemical properties render these chitinases likely suitable for shrimp chitin processing including one-step chitin hydrolysis and alternative sustainable protein processing and the attractive emerging application of mushroom food waste valorisation.
Key points
• Two GH18 chitinases originating from the industrially relevant thermophilic fungus R. emersonii were cloned and expressed in P. pastoris.
• The purified recombinant chitinases showed low pH and high temperature optima and appreciable thermostability at industrially relevant temperatures.
• The chitinases displayed characteristics that indicate their likely suitability to several industrial applications including sustainable alternative protein processing, food waste valorisation of commercial mushroom production and one-step shrimp chitin processing.
An acid-active exo/endo-chitinase; comprising a GH18 catalytic domain and substrate insertion domain; originating from the thermophilic filamentous fungus
Rasamsonia emersonii,
was expressed in
...Pichia pastoris
. In silico analysis including phylogenetic analysis, and recombinant production, purification, biochemical characterisation, and industrial application testing, was carried out. The expressed protein was identified by SDS-PAGE as a smear from 56.3 to 125.1 kDa, which sharpens into bands at 46.0 kDa, 48.4 kDa and a smear above 60 kDa when treated with PNGase F. The acid-active chitinase was primarily a chitobiosidase but displayed some endo-chitinase and acetyl-glucosamidase activity. The enzyme was optimally active at 50 °C, and markedly low pH of 2.8. As far as the authors are aware, this is the lowest pH optima reported for any fungal chitinase. The acid-active chitinase likely plays a role in chitin degradation for cell uptake in its native environment, perhaps in conjunction with a chitin deacetylase. Comparative studies with other
R. emersonii
chitinases indicate that they may play a synergistic role in this. The acid-active chitinase displayed some efficacy against non-treated substrates; fungal chitin and chitin from shrimp. Thus, it may be suited to industrial chitin hydrolysis reactions for extraction of glucosamine and chitobiose at low pH.
Bird bills possess an important thermoregulatory function as they are a site for environmental heat exchange. Previous studies have demonstrated that birds in warmer climates have larger bills than ...those living in colder climates, as larger bills can dissipate more heat. Because this dry heat transfer does not incur water loss, it may be additionally advantageous in water‐restricted habitats. Here, we examine the influence of climate on bill morphology in Toxostoma thrashers, a group of 10 North American species that varied in bill morphology and occupied climate niche, with several species inhabiting arid climates. Past examinations of thrasher bill morphology have only considered foraging, leaving unanswered the role of climate in morphological divergence within this group. We photographed 476 Toxostoma museum specimens encompassing all 10 species and calculated bill measurements from the photos using a MATLAB‐based program. For each species, we calculated occupied climate niche using data from WorldClim describing temperature and precipitation. We found no reliable significant relationships between climate variables and bill morphology across species, suggesting that other factors such as foraging behavior may be more important in shaping bill morphology in this genus. Within species, we found three Toxostoma species have significant relationships between bill morphology and climate that follow Allen's rule. However, we also found the relationships between climate and bill morphology varied in strength and direction across species. Notably, we found a negative relationship between maximum temperature of the hottest month and bill surface area in LeConte's thrasher, which occupies the hottest and most arid climates of the thrashers. This adds to the evidence that Allen's rule may reverse in extremely hot climates when the bill may become a heat sink instead of a heat radiator. These results demonstrate the importance of considering the generality of ecogeographical rules across lineages that occupy extreme climates.
One of the biggest challenges with species conservation is collecting accurate and efficient information on population sizes, especially from species that are difficult to count. Bats worldwide are ...declining due to disease, habitat destruction, and climate change, and many species lack reliable population information to guide management decisions. Current approaches for estimating population sizes of bats in densely occupied colonies are time-intensive, may negatively impact the population due to disturbance, and/or have low accuracy. Research-based video tracking options are rarely used by conservation or management agencies for animal counting due to the perceived training and elevated operating costs. In this paper, we present BatCount, a free software program created in direct consultation with end-users designed to automatically count bats emerging from cave roosts (historical populations 20,000-250,000) with a streamlined and user-friendly interface. We report on the software package and provide performance metrics for different recording habitat conditions. Our analysis demonstrates that BatCount is an efficient and reliable option for counting bats in flight, with performance hundreds of times faster than manual counting, and has important implications for range- and species-wide population monitoring. Furthermore, this software can be extended to count any organisms moving across a camera including birds, mammals, fish or insects.
This two-experiment study aimed to examine the effects of different habitual foot placement angles and also the effects of manipulating the foot placement angle on the kinetics, three-dimensional ...kinematics and muscle forces of the squat. In experiment 1, seventy lifters completed squats at 70% of their one repetition maximum using a self-preferred placement angle. They were separated based on their habitual foot angle into three groups HIGH, MEDIUM and LOW. In experiment 2, twenty lifters performed squats using the same relative mass in four different foot placement angle conditions (0°, 21°, 42° and control). Three-dimensional kinematics were measured using an eight-camera motion analysis system, ground reaction forces (GRF) using a force platform, and muscle forces using musculoskeletal modelling techniques. In experiment 1, the impulse of the medial GRF, in the descent and ascent phases, was significantly greater in the HIGH group compared to LOW, and in experiment 2 statistically greater in the 42° compared to the 21°, 0° and control conditions. Experiment 2 showed that the control condition statistically increased quadriceps muscle forces in relation to 0°, whereas the 0° condition significantly enhanced gluteus maximus, gastrocnemius and soleus forces compared to control. In experiment 1, patellofemoral joint stress was significantly greater in the HIGH group compared to LOW, and in experiment 2, patellar and patellofemoral loading were statistically greater in the control compared to the 42°, 21°, 0° and control conditions. Owing to the greater medial GRF’s, increased foot placement angles may improve physical preparedness for sprint performance and rapid changes of direction. Reducing the foot angle may attenuate the biomechanical mechanisms linked to the aetiology of knee pathologies and to promote gluteus maximus, gastrocnemius and soleus muscular development. As such, though there does not appear to be an optimal foot placement angle, the observations from this study can be utilised by both strength and conditioning and sports therapy practitioners seeking to maximise training and rehabilitative adaptations.
In this follow-up article, we investigate the use of convolutional neural network for deriving stellar parameters from observed spectra. Using hyperparameters determined previously, we have ...constructed a Neural Network architecture suitable for the derivation of
,
,
, and
. The network was constrained by applying it to databases of AFGK synthetic spectra at different resolutions. Then, parameters of A stars from Polarbase, SOPHIE, and ELODIE databases are derived, as well as those of FGK stars from the spectroscopic survey of stars in the solar neighbourhood. The network model’s average accuracy on the stellar parameters is found to be as low as 80 K for
, 0.06 dex for
, 0.08 dex for
, and 3 km/s for
for AFGK stars.
This two-experiment study aimed to explore habitual and manipulated stance widths on squat biomechanics. In experiment one, 70 lifters completed back squats at 70%, 1 repetition maximum (1RM), and ...were split into groups (NARROW < 1.06 * greater trochanter width (GTW), MID 1.06−1.18 * GTW and WIDE > 1.37 * GTW) according to their self-selected stance width. In experiment two, 20 lifters performed squats at 70%, 1RM, in three conditions (NARROW, MID and WIDE, 1.0, 1.25 and 1.5 * GTW). The three-dimensional kinematics were measured using a motion capture system, ground reaction forces (GRF) using a force platform, and the muscle forces using musculoskeletal modelling. In experiment two, the peak power was significantly greater in the NARROW condition, whereas both experiments showed the medial GRF impulse was significantly greater in the WIDE stance. Experiment two showed the NARROW condition significantly increased the quadriceps forces, whereas both experiments showed that the WIDE stance width significantly enhanced the posterior-chain muscle forces. The NARROW condition may improve the high mechanical power movement performance and promote the quadriceps muscle development. Greater stance widths may improve sprint and rapid change-of-direction performance and promote posterior-chain muscle hypertrophy. Whilst it appears that there is not an optimal stance width, these observations can be utilized by strength and conditioning practitioners seeking to maximize training adaptations.
Machine learning is an efficient method for analysing and interpreting the increasing amount of astronomical data that are available. In this study, we show a pedagogical approach that should benefit ...anyone willing to experiment with deep learning techniques in the context of stellar parameter determination. Using the convolutional neural network architecture, we give a step-by-step overview of how to select the optimal parameters for deriving the most accurate values for the stellar parameters of stars:
,
, M/H, and
. Synthetic spectra with random noise were used to constrain this method and to mimic the observations. We found that each stellar parameter requires a different combination of network hyperparameters and the maximum accuracy reached depends on this combination as well as the signal-to-noise ratio of the observations, and the architecture of the network. We also show that this technique can be applied to other spectral-types in different wavelength ranges after the technique has been optimized.
Many bats form colonies and undergo nightly emergence in dense, fast-moving streams. Although the flight mechanics of individual bats have been well studied, the effect of flying in a group has not ...been studied with large aggregations under natural conditions. We tested the hypothesis that group size affects flight mechanics and behaviour in Brazilian free-tailed bats, Tadarida brasiliensis. We measured the flight path, flight path time and wing beat rate of individual bats by analysing videos of bats in flight and compared values across different flight group sizes. Flight path, flight speed and wing beat rate of individual bats were all unaffected by group size. Additionally, bats maintained a constant wing beat rate regardless of flight speed. These results suggest that Brazilian free-tailed bats experience neither an aerodynamic benefit nor a cost to travelling in groups.
•We investigated the effect of group size on bat flight.•Bats did not alter wing beat rate or flight speed with changes in group size.•Constant, predictable flight behaviour may facilitate navigation in large groups.
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