Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

Recurrent Pseudo-nitzschia calliantha (Bacillariophyceae) and Alexandrium insuetum (Dinophyceae) winter blooms induced by agricultural runoff

A winter bloom dominated by Pseudo-nitzschia calliantha Lundholm, Moestrup et Hasle (Bacillariophyceae), a potential domoic acid producer, is reported for the first time in the Aegean Sea, Greece, in a semi-enclosed embayment (Kalloni Gulf) surrounded by agricultural land and drained by intermittent rivers. Abundances of this species in the inner part of the Gulf during February were extremely high (max 1.1 × 10⁷ cells l⁻¹). The species Alexandrium insuetum Balech (Dinophyceae) was also found in considerable cell numbers (max 1.4 × 10⁵ cells l⁻¹) during the bloom and reached up to 40% of the total biovolume. This study demonstrates an evident cause and effect relationship between nutrient inflows originating from agricultural activities in the watershed and the development of a potential HAB. The massive bloom formation was observed soon after an episodic rainfall event during the fertilizer application period (December to February). A bloom was also observed the following year, but it was less pronounced due to the fact that rainfalls were more evenly spaced in time and were of moderate intensity.     

Relation between endurance time and maximal oxygen consumption during supramaximal running

The relationship between speed and the maximal length of time supramaximal runs can be sustained (temps-limite, tlim) has been studied in seven male subjects (physical education students). Within the range of intensity studied, tlim strictly depends on maximal oxygen consumption (VO2max). The relationship between tlim and the relative energy cost of the exercises per unit of time (E), calculated by subtracting the maximal power of aerobic metabolism (Emaxox) from E, removes the interindividual differences of tlim. The function tlim = f(E-Emaxox) is described by an empirical equation of the form: tlim = a.exp[-b(E-Emaxox)] (r = 0.979; P less than 0.001), where the parameters a and b are respectively equal to 330.8 and 0.14 and where tlim, E and Emaxox are respectively expressed in seconds and in watts per kg of body weight.     

Age and sex composition of small ruminants at Nouakchott markets, Mauritania

A survey of species, breeds, sex and age composition of sheep and goats offered for sale was made at Nouakchott (Mauritania) livestock markets. Some 82.8% of animals presented at the markets were sheep and 95% of these were of the Short-haired Maure breed, the remainder being Long-haired Maure. Goats of the Sahel breed comprised 81% of all animals of this species, the others being Sahara and Eastern Dwarf types, but goats represented only 17.2% of all animals brought to market. Castrated Short-haired Maure sheep were 63.6% of this breed whereas castrates of Long-haired Maure sheep were 40.6% of the total. There were significantly more castrates than entire males presented for sale for sheep but the reverse was the case for goats. Entire males of both species were sold at younger ages than castrates and males and castrates combined were sold at younger ages than females. This study has provided some indications of the types of stock offered for sale but further studies at peak sale times would allow more detailed analysis. Such an analysis should be coupled with a survey of owners/herders and of traders in order to determine the factors operating on market forces.     

Cardiovascular changes induced by isometric exercise in aged subjects

Blood pressure and heart rate during static contraction of forearm muscles holding a tension of 30% maximal voluntary strength for 5 mn have been measured. Eleven young men and 11 elderly male subjects were used. Maximal voluntary strength is reduced by 19% in elderly subjects. Relative mean cardio-vascular responses were unaffected by age.     

Design and visualization of second‐generation cyanoisoindole‐based fluorescent strigolactone analogs

Strigolactones (SLs) are a family of terpenoid allelochemicals that were recognized as plant hormones only a decade ago. They influence a myriad of both above‐ and below‐ground developmental processes, and are an important survival strategy for plants in nutrient‐deprived soils. A rapidly emerging approach to gain knowledge on hormone signaling is the use of traceable analogs. A unique class of labeled SL analogs was constructed, in which the original tricyclic lactone moiety of natural SLs is replaced by a fluorescent cyanoisoindole ring system. Biological evaluation as parasitic seed germination stimulant and hypocotyl elongation repressor proved the potency of the cyanoisoindole strigolactone analogs (CISAs) to be comparable to the commonly accepted standard GR24. Additionally, via a SMXL6 protein degradation assay, we provided molecular evidence that the compounds elicit SL‐like responses through the natural signaling cascade. All CISAs were shown to exhibit fluorescent properties, and the high quantum yield and Stokes shift of the pyrroloindole derivative CISA‐7 also enabled in vivo visualization in plants. In contrast to the previously reported fluorescent analogs, CISA‐7 displays a large similarity in shape and structure with natural SLs, which renders the analog a promising tracer to investigate the spatiotemporal distribution of SLs in plants and fungi.     

Mitogenomics reveals high synteny and long evolutionary histories of sympatric cryptic nematode species

Species with seemingly identical morphology but with distinct genetic differences are abundant in the marine environment and frequently co‐occur in the same habitat. Such cryptic species are typically delineated using a limited number of mitochondrial and/or nuclear marker genes, which do not yield information on gene order and gene content of the genomes under consideration. We used next‐generation sequencing to study the composition of the mitochondrial genomes of four sympatrically distributed cryptic species of the Litoditis marina species complex (PmI, PmII, PmIII, and PmIV). The ecology, biology, and natural occurrence of these four species are well known, but the evolutionary processes behind this cryptic speciation remain largely unknown. The gene order of the mitochondrial genomes of the four species was conserved, but differences in genome length, gene length, and codon usage were observed. The atp8 gene was lacking in all four species. Phylogenetic analyses confirm that PmI and PmIV are sister species and that PmIII diverged earliest. The most recent common ancestor of the four cryptic species was estimated to have diverged 16 MYA. Synonymous mutations outnumbered nonsynonymous changes in all protein‐encoding genes, with the Complex IV genes (coxI‐III) experiencing the strongest purifying selection. Our mitogenomic results show that morphologically similar species can have long evolutionary histories and that PmIII has several differences in genetic makeup compared to the three other species, which may explain why it is better adapted to higher temperatures than the other species.