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.     

The benefits of interpopulation hybridization diminish with increasing divergence of small populations

Interpopulation hybridization can increase the viability of small populations suffering from inbreeding and genetic drift, but it can also result in outbreeding depression. The outcome of hybridization can depend on various factors, including the level of genetic divergence between the populations, and the number of source populations. Furthermore, the effects of hybridization can change between generations following the hybridization. We studied the effects of population divergence (low vs. high level of divergence) and the number of source populations (two vs. four source populations) on the viability of hybrid populations using experimental Drosophila littoralis populations. Population viability was measured for seven generations after hybridization as proportion of populations facing extinction and as per capita offspring production. Hybrid populations established at the low level of population divergence were more viable than the inbred source populations and had higher offspring production than the large control population. The positive effects of hybridization lasted for the seven generations. In contrast, at the high level of divergence, the viability of the hybrid populations was not significantly different from the inbred source populations, and offspring production in the hybrid populations was lower than in the large control population. The number of source populations did not have a significant effect at either low or high level of population divergence. The study shows that the benefits of interpopulation hybridization may decrease with increasing divergence of the populations, even when the populations share identical environmental conditions. We discuss the possible genetic mechanisms explaining the results and address the implications for conservation of populations.     

Distribution of histamine in the rat kidney during pregnancy and development

Summary An antiserum against conjugated histamine and two oligonucleotide probes that detect the mRNA encoding L-histidine decarboxylase (HDC) involved in histamine synthesis were used to study the appearance of histamine and its location in the kidneys of fetal, newborn and young postnatal rats and in the kidneys of pregnant rats. On embryonic days 16 and 18 (E16 and E18), some HA-immunoreactive (HA-ir) cells were found within the largest S-shaped bodies. Histamine was found to appear rapidly between the 18th and 20th embryonic days in the convoluted tubules of the kidneys. On postnatal day 0 (P0), the distal convoluted tubules and collecting ducts exhibited bright fluorescence, the intensity of which decreased quickly so that it was faint on day P4 and absent at later stages. In kidneys of pregnant rats HA-ir was found in the epithelium of both the Bowman's capsule, collecting ducts and in a few cells within the tubules. Nonuniform HA-ir was also detected within glomeruli. No evidence for the presence of L-histidine decarboxylase mRNA in kidneys of fetuses or pregnant rats was seen. It is concluded that distinct structures in the developing rat kidney contain histamine during a period around birth from day E20 to day P4. In the pregnant rat, the epithelium that is in direct contact with the urine flow is immunoreactive for histamine from day 16 to 20 of pregnancy. The results suggest that histamine is not synthesized locally in the kidneys but rather originates from other tissues.     

Risk factors and 25 year risk of coronary heart disease in a male population with a high incidence of the disease: the Finnish cohorts of the seven countries study.

OBJECTIVE--To assess the efficacy of high serum cholesterol concentration, raised blood pressure, and smoking as predictors of coronary heart disease. DESIGN--Prospective cohort study of middle aged men conducted over 25 years. SETTING--Finish components of an ongoing international study (seven countries study). PARTICIPANTS--1520 Men who at age 40-59 in 1959 were free of clinically evident heart disease. INTERVENTIONS--At each follow up visit a detailed medical examination including resting electrocardiography was performed, blood pressure and serum total cholesterol concentration were measured, and smoking was assessed. MEASUREMENTS AND MAIN RESULTS--825 Deaths (54% of participants) occurred during follow up, of which 335 were due to coronary heart disease. The hazard ratio for death from coronary heart disease with respect to risk factors at entry were: for serum cholesterol concentrations above 8.4 mmol/l v below 5.2 mmol/l, 2.68 (95% confidence interval 1.62 to 4.42); for systolic blood pressure in the highest quintile v that in the lowest quintile, 2.46 (1.72 to 3.50); and for smoking 10 or more cigarettes daily v never smoking, 1.95 (1.36 to 2.79). The hazard ratios with respect to cholesterol concentrations and blood pressure remained constant during follow up but the ratio with respect to smoking diminished, mainly owing to men giving up the habit. The estimated conditional probability of a 50 year old man dying of coronary heart disease in the next 25 years ranged from 12% among those with the most favourable risk factor profile to 75% among those with the least favourable profile. CONCLUSIONS--High risk factor levels (as determined in this study) in middle aged men may greatly increase the absolute probability of death from coronary heart disease when the period of study is relevant to the human life span.     

Colonization and deterioration processes in Roman mortars by cyanobacteria,algae and lichens

The mortars covering some walls of the Roman city of Baelo Claudia (Cadiz, Spain) support an abundant colonization of cyanobacteria, algae and lichens. The distribution of these organisms is closely related to microclimatic parameters. Furthermore, the development, specific composition and biomass of algal cryptoendolithic communities are related to the wall orientation. The effect of these communities on mortar deterioration is discussed.     

Molecular characterization of a fourth isoform of the catalytic subunit of protein phosphatase 2A from Arabidopsis thaliana

We have recently reported the existence of multiple isoforms of the catalytic subunit of protein phosphatase 2A (PP2A) in Arabidopsis thaliana and the molecular cloning of cDNAs encoding three of these proteins (PP2A-1, PP2A-2, PP2A-3). The reported cDNA encoding PP2A-3 was truncated at the 5 terminus, lacking a short fragment of the N-terminal coding sequence. We have now isolated a near full-length cDNA encoding the entire PP2A-3 protein (313 residues). The clone includes 188 nucleotides of 5-untranslated region, where a 44 bp long poly(GA) track is found. We also describe the cloning of a cDNA encoding a fourth isoform of PP2A (PP2A-4). The polypeptide contains 313 residues being 98% identical to PP2A-3 and only 80% identical to both PP2A-1 and PP2A-2. The mRNA for PP2A-4 is 1.4 kb in length and, although predominantly expressed in roots, it is also found in other organs. It is concluded that in A. thaliana the isoforms of PP2A can be grouped in two extremely conserved subfamilies.     

REPRODUCTIVE SEASONALITY OF WESTERN ATLANTIC BOTTLENOSE DOLPHINS OFF NORTH CAROLINA, U.S.A.

We describe reproductive seasonality of bottlenose dolphins in North Carolina (NC), U.S.A., using strandings data from the entire coast of NC and sighting data from Beaufort, NC and by estimating dates of birth of known females. We found a strong peak of neonate strandings in the spring (April-May), and low levels of neonate strandings in the fall and winter. The distribution of neonate strandings was significantly different from a uniform distribution ( P < 0.001, K = 3.8). We found a unimodal distribution of 282 sightings of neonates with a diffuse peak in the summer. The temporal distribution of sightings of neonates departed significantly from a uniform distribution (P < 0.001, K = 5.1). Estimated birth dates of neonates from known females occurred in May ( n = 6) and June ( n = 4), with a single fall birth. These methods shed light on bottlenose reproductive patterns and underscore the value of using information from multiple types of data. Clarification of bottlenose dolphin reproductive patterns, such as the seasonality of birth, may enhance our understanding of the population structure of this species in the mid-Atlantic region.     

Changes in cytoplasmic and lysosomal enzyme activities in cultured rat heart cells: The relationship to cell differentiation and cell population in culture

Summary Postnatal rat heart cells in culture enriched with respect to muscle cells were obtained by either high density seeding or by the replating technique. [³H]Thymidine incorporation to DNA and the enzymatic pattern of cytoplasmic and lysosomal enzymes have been studied as a function of the culture’s age, of seeding density, and replating. It was shown that (a) replating maintains predominance of myocyte population for at least 2 wk in culture; (b) heavy seeding density allows homogeneous myocyte population for the 1st wk in culture; and (c) the enzyme profile of the culture may serve as an indicator for the type of cell population in culture and its state of differentiation. This study was done as partial fulfilment of the M.Sc. thesis in Biochemistry (SY). Supported by grants from The Chief Scientist, Ministry of Health, State of Israel; The Ministry of Education and Sciences, State of Niedersachssen (FRG); and The Foundation for Heart Research from Mr. and Mrs. D. Vidal-Madjar, Paris, France.