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Oceanicola granulosus gen. nov., sp. nov. and Oceanicola batsensis sp. nov., poly-beta-hydroxybutyrate-producing marine bacteria in the order 'Rhodobacterales'.

Three Gram-negative, chemoheterotrophic, non-motile, rod-shaped bacterial strains that accumulate poly-beta-hydroxybutyrate granules were isolated from the Bermuda Atlantic Time-series Study site by high-throughput culturing methods and characterized by polyphasic approaches. DNA-DNA hybridization, DNA G+C content and phylogenetic analyses based on 16S rRNA gene sequences divided the three isolates into two distinct genospecies that were clearly differentiated by fatty acid profiles, carbon source utilization patterns, antibiotic susceptibility and biochemical characteristics. The strains utilized a wide range of substrates, including pentoses, hexoses, oligosaccharides, sugar alcohols, organic acids and amino acids. DNA G+C contents were 71.5, 70.9 and 67.3 mol% for strains HTCC2516T, HTCC2523 and HTCC2597T, respectively. The most dominant fatty acid was 18 : 1omega7c in strains HTCC2516T and HTCC2523, and cyclo 19 : 0 in strain HTCC2597T. The type strains HTCC2516T and HTCC2597T were clearly differentiated by the presence or absence of 12 : 0, 12 : 1omega11c, 14 : 0, 15 : 0 and methyl 18 : 1. Phylogenetic analyses indicated that the strains formed a distinct monophyletic lineage within the Roseobacter clade in the order 'Rhodobacterales' of the Alphaproteobacteria, and which did not associate with any of the described genera. Genotypic and phenotypic differences of the isolates from the previously described genera support the description of Oceanicola granulosus gen. nov., sp. nov. with the type strain HTCC2516T (=ATCC BAA-861T=DSM 15982T=KCTC 12143T) and of Oceanicola batsensis sp. nov. with the type strain HTCC2597T (=ATCC BAA-863T=DSM 15984T=KCTC 12145T).

Acids↗

Types and frequencies of sequencing errors in methyl-filtered and high c0t maize genome survey sequences.

The Maize Genome Sequencing Consortium has deposited into GenBank more than 850,000 maize (Zea mays) genome survey sequences (GSSs) generated via two gene enrichment strategies, methylation filtration and high-C(0)t (HC) fractionation. These GSSs are a valuable resource for generating genome assemblies and the discovery of single nucleotide polymorphisms and nearly identical paralogs. Based on the rate of mismatches between 183 GSSs (105 methylation filtration + 78 HC) and 10 control genes, the rate of sequencing errors in these GSSs is 2.3 x 10(-3). As expected many of these errors were derived from insufficient vector trimming and base-calling errors. Surprisingly, however, some errors were due to cloning artifacts. These G.C to A.T transitions are restricted to HC clones; over 40% of HC clones contain at least one such artifact. Because it is not possible to distinguish the cloning artifacts from biologically relevant polymorphisms, HC sequences should be used with caution for the discovery of single nucleotide polymorphisms or paramorphisms. The average rate of sequencing errors was reduced 6-fold (to 3.6 x 10(-4)) by applying more stringent trimming parameters. This trimming resulted in the loss of only 11% of the bases (15,469/144,968). Due to redundancy among GSSs this more stringent trimming reduced coverage of promoters, exons, and introns by only 0%, 1%, and 4%, respectively. Hence, at the cost of a very modest loss of gene coverage, the quality of these maize GSSs can approach Bermuda standards, even prior to assembly.

DNA, Plant↗

The requirement for sodium as a micronutrient by species having the c(4) dicarboxylic photosynthetic pathway.

Six species having characteristics of plants with the C(4) dicarboxylic photosynthetic pathway, Echinochloa utilis L. Ohwi et Yabuno (Japanese millet), Cynodon dactylon L. (Bermuda grass), Kyllinga brevifolia Rottb., Amaranthus tricolor L. cv. Early splendour, Kochia childsii Hort., and Portulaca grandiflora Hook (rose moss), responded decisively to 0.1 milliequivalent per liter NaCl supplied to their culture solutions initially containing less than 0.08 microequivalent per liter Na. Chlorosis and necrosis occurred in leaves of plants not receiving sodium. Portulaca failed to set flower in the sodium-deficient cultures. Under similar conditions Poa pratensis L. (Kentucky blue grass) having characteristics of the C(3) photosynthetic pathway made normal growth and did not respond to the addition of sodium. It is concluded from these results and previously reported work that sodium is generally essential for species having the C(4) pathway but not for species with the C(3) pathway.

Journal Article↗

Speciation on the coasts of the new world: phylogeography and the evolution of bindin in the sea urchin genus Lytechinus.

Beginning with E. Mayr's study in 1954, tropical sea urchins have played an important role in studies of speciation in the sea, but what are the processes of cladogenesis and divergence that give rise to new species in this group? We attempt to answer this question in the genus Lytechinus. Unlike the majority of other tropical sea urchin genera, which have circumtropical distributions, Lytechinus is mostly confined to the tropics and subtropics of the New World. We sequenced a region of mitochondrial cytochrome oxidase I and the entire molecule of nuclear bindin (a sperm gamete recognition protein) of nearly all species in the genus, and we assayed isozymes of three partially sympatric closely related species and subspecies. We found that in both mitochondrial DNA (mtDNA) and in bindin the genus Lytechinus is paraphyletic, encompassing Sphaerechinus granularis as the sister species of L. euerces. The rest of the species are arranged in an Atlantic clade composed of L. williamsi and L. variegatus, and a Pacific clade containing L. anamesus, L. pictus, L. semituberculatus, and L. panamensis. Divergence between these clades suggests that they were separated no later than the closure of the Isthmus of Panama, and possibly before this time. Our data confirm that L. anamesus and L. pictus from California are a single species, and provide no evidence of differentiation between L. variegatus variegatus from the Caribbean and L. variegatus atlanticus from Bermuda. Lytechinus variegatus variegatus mtDNA is distinct from that of L. variegatus carolinus from the North American seaboard and the Gulf of Mexico, whereas their bindins are very similar. However, there is clear evidence of introgression of mtDNA between the two subspecies and they share alleles in all sampled isozyme loci. Lytechinus williamsi from the Caribbean shares mtDNA haplotypes with L. variegatus variegatus, and they also share isozymes in all assayed loci. Their bindin, however, is distinct and coalesces within each morphospecies. A private clade of mtDNA in L. williamsi may be indicative of former differentiation in the process of being swamped by introgression, or of recent speciation. Recent sudden expansions in effective population size may explain the predominance of a few mitochondrial haplotypes common to the two species. Despite the high divergence of bindin (relative to differentiation of mtDNA) between L. variegatus and L. williamsi, comparison of amino acid replacement to silent substitutions by various methods uncovered no evidence for positive selection on the bindin of any clade of Lytechinus. With the possible exception of L. williamsi and L. variegatus, our results are consistent with a history of allopatric speciation in Lytechinus. The molecular results from Lytechinus, along with those of other similar studies of sea urchins, suggest that the general speciation patterns deduced in the middle of last century by Mayr from morphology and geography have held up, but also have uncovered peculiarities in the evolution of each genus.

Americas↗

Efficacy of grass-maize pollen oral immunotherapy in patients with seasonal hay-fever: a double-blind study.

Forty patients with a well-documented history of seasonal hay fever and a positive skin-prick test specific to grass pollen, including Bermuda grass and maize pollen (Zea maize), were allocated randomly on a double-blind basis to receive either an oral mixed grass-maize pollen extract or a matched placebo during the 1981/1982 grass pollen season. After 12 months the code was broken and patients on placebo were transferred to active therapy while patients on active therapy continued with maintenance therapy for another 12 months during the 1982/1983 grass pollen season. The assessment of the effect of the orally administered grass-maize pollen extract was on the clinical symptoms. During the first year the patients on active therapy had significantly fewer hay fever symptoms during the summer months compared with the placebo group. During the second study year, with all patients on active therapy, both groups had markedly milder symptoms compared with the placebo group. Side-effects were negligible. This study concludes that oral immunotherapy with grass-maize pollen extract in grass pollen-sensitive seasonal hay fever patients is safe and effective.

Administration, Oral↗

The house dust mite Dermatophagoides pteronyssinus is the most important allergen on the island of Mauritius.

To determine the relative importance of mites as a cause of allergic sensitivity and asthma on the western Indian Ocean island of Mauritius, we measured specific IgE antibodies to common inhalant allergens in sera from Mauritians claiming to have allergic symptoms and we examined house dust samples for evidence of mites and their allergens. Seventy-two of the 110 sera tested (65%) contained detectable IgE antibody to at least one mite, mould or pollen allergenic extract. By far the most prevalent was antibody to one or both of the common house dust mites, Dermatophagoides pteronyssinus and Dermatophagoides farinae, being present in 67 (61%) of the 110 sera. Allergy to pollens, including the locally prevalent Bermuda grass and sugar cane, was infrequent. Antibody to a limited number of moulds was detected in 22% of the sera tested. Of 81 subjects whose clinical history was known, 60 were asthmatic, and 75% of these asthmatic individuals had IgE antibody to mites. In contrast, only 35% of the subjects with rhinitis without asthma were sensitive to mites. Different mite species, including D. pteronyssinus but not D. farinae, were identified microscopically in samples of local house dust. Mite antigen Der p I but not antigen Der f I was detected with specific monoclonal antibodies in extracts of these dust samples. On the bases of this serological and environmental survey, we conclude that our data support the hypothesis that the house dust mite D. pteronyssinus is the principal cause of allergic sensitivity and asthma in that tropical environment.

Adolescent↗

IgE specific immune responses to an African grass (Kikuyu, Pennisetum clandestinum)

Kikuyu grass (Pennisetum clandestinum) is widely used as a grazing pasture in Africa and, although it is extensively cultivated as a lawn for sports fields and domestic gardens, its allergenicity has never been studied in vitro. Using an extract of Kikuyu grass pollen, polyacrylamide gel electrophoresis, Western blotting and a monoclonal anti-human IgE antibody, the specific IgE binding, in the serum of 160 allergic and non-allergic patients in the Cape Town area, to a Kikuyu grass extract was studied. IgE in the sera of 43/104 known grass-allergic individuals bound to Kikuyu grass on the Western blots. In addition, 4/28 'non-allergic' control subjects were found to have Kikuyu grass-specific IgE. Five different profiles of specific IgE reactivity to Kikuyu grass antigens were observed. In 29/43 patients, IgE bound to two dominant 48 and 70 kD allergens in the Kikuyu extract. Although a degree of cross-reactivity with Bermuda grass (Cynodon dactylis) was found in immunoabsorption studies, the 48 and 70 kD allergens appear to be unique to Kikuyu grass. Exposure of heparinized blood from Kikuyu grass-positive patients to the Kikuyu extract stimulated the release of histamine from their basophils in vitro. Kikuyu grass pollen is thus identified as an important aero-allergen in South Africa.

Allergens↗

Dynamic changes in sensitization to specific aeroallergens in children raised in a desert environment.

BACKGROUND: Allergen skin test reactivity and total serum IgE are objective measures used to characterize and help diagnose allergic diseases. Cross-sectional studies have shown that overall aeroallergen skin test reactivity increases throughout childhood. However, little attention has been paid to whether individual aeroallergen remittance occurs, which could distort or mask relationships to disease. OBJECTIVE: To access the incidence and remittance of skin test reactions to individual allergens in children aged 6-11 years. METHODS: Longitudinal sensitization to six aeroallergens and total IgE were assessed in 828 children raised in the semi-arid US southwest at ages 6 and 11 years. RESULTS: New sensitization (to any allergen) between 6 and 11 years occurred in 30.2% of children compared with 39.7% before age 6 years. The rate of complete remittance from positive to negative between ages 6 and 11 years was 8.2%, and total IgE at age 6 years was not predictive. Remittance rates for individual allergens were high and variable (19-49%). The perennial allergens Bermuda and Alternaria were early sensitizers and had low remittance rates. Early sensitization to the four seasonal allergens was less common and more subject to remittance with the bulk of sensitization occurring between 6 and 11 years. CONCLUSION: This study shows that sensitization to individual aeroallergens in childhood is dynamic and indicates the limitation of single point assessment of skin test reactivity.

Air↗

Cloning, expression and immunological characterization of full-length timothy grass pollen allergen Phl p 4, a berberine bridge enzyme-like protein with homology to celery allergen Api g 5.

BACKGROUND: Timothy grass pollen is a common cause of respiratory allergy in the temperate regions. The major group 4 allergen, Phl p 4, has previously been purified and studied biochemically and immunologically, but has so far not been produced and characterized as a recombinant protein. OBJECTIVE: To clone and characterize timothy grass pollen allergen Phl p 4. METHODS: Full-length Phl p 4 cDNA was cloned using a PCR-based strategy including 3'-and 5'-RACE. Recombinant Phl p 4 was expressed in Escherichia coli and purified by immobilized metal ion affinity chromatography. Its immunological activity was investigated using experimental ImmunoCAP tests, sera from Phl p 4 sensitized individuals and Phl p 4 reactive polyclonal and monoclonal animal antibodies. RESULTS: Five full-length Phl p 4 cDNA clones were analysed. Sequence deviations between the clones were present at nine amino acid positions, and the consensus sequence comprised an open reading frame of 525 amino acids, including a predicted 25-residue signal peptide. The calculated molecular weight of the deduced mature protein was 55.6 kDa and the isoelectric point 9.9, both consistent with previously observed properties of purified nPhl p 4. Close sequence similarity was found to genomic clones from several other Pooideae grass species and to Bermuda grass pollen allergen BG60. Further, similarity was found to members of the berberine bridge enzyme (BBE) family, including celery allergen Api g 5. Recombinant Phl p 4 bound specific immunoglobulin (Ig)E from 31 of 32 nPhl p 4-reactive sera, and the IgE binding to rPhl p 4 could be inhibited by nPhl p 4 in a dose-dependent manner. CONCLUSIONS: Full-length Phl p 4 cDNA was cloned and showed sequence similarity to members of the BBE family. Recombinant Phl p 4 was produced and shared epitopes with natural Phl p 4.

Allergens↗

Atopy patch testing with aeroallergens in patients with atopic dermatitis and controls in Singapore.

The role of allergy in atopic dermatitis is controversial. The atopy patch test (APT) has been used to investigate the association between atopic dermatitis and aeroallergen allergy. To determine the proportion of patients with atopic dermatitis with positive patch tests to common local aeroallergens and to compare this to controls with and without respiratory atopy, we performed APT, skin-prick tests (SPT) and IgE radioallergosorbent tests (RAST) on 73 patients with atopic dermatitis and on 38 nonatopic controls (13 with and 25 without respiratory atopy). The allergens used were house dust mite, cat dander, Bermuda grass and German cockroach. Only the APT for house dust mite showed a significant difference between the two groups. APT for house dust mite correlated with the RAST test, while APT for cat fur correlated with the SPT. The APT may be useful to evaluate aeroallergens in atopic dermatitis, but further work is needed to make it more reliable.

Adolescent↗

Major allergens of date palm (Phoenix dactylifera L.) pollen. Identification of IgE-binding components by ELISA and immunoblot analysis.

The IgE-binding components of date palm (Phoenix dactylifera L.) pollen were determined by ELISA and Western blotting in atopic patients in order to identify its major allergens. From a pool of previously identified allergenic fractions and sera from 15 skin-test-positive, atopic subjects, four components of 12, 14.4, 57, and 65-67 kDa were found to bind IgE in 80-93% of sera. Two other components of molecular masses 28-30 and 37-40 kDa also bound 60-80% of atopic sera. The immunologic specificity of date-pollen allergen that induced antibody response in sera of atopic patients was confirmed with ELISA. Furthermore, most of the reactivity in pooled positive atopic serum and antiserum raised in rabbits was eliminated after the sera were absorbed with the allergen. IgG immunoblot analyses showed varying degrees of cross-reactivity with common local allergens, notably Bermuda grass, but were generally of low intensity. These results indicate that date pollen has six major allergens with the 12, 14.4, 57, and 65-67 kDa bands binding 80-93%, and the 28-30 and 37-40 kDa bands 60-80% of atopic sera. We propose that these major allergens be assigned the notations "Pho d I" to "Pho d VI" in the order listed.

Allergens↗

Prevalence of allergic sensitization to inhalant allergens among blood donors in Kuwait--a desert country.

Kuwait is a desert country where the prevailing high temperatures, low humidity, and scant vegetation suggest a low prevalence of allergy. We evaluated the prevalence of atopic sensitization (presence of allergen-specific IgE) among young adult blood donors by screening a total of 505 subjects (male: female ratio 1.6) with mean age of 28.4 years (range 18-50 years). The Pharmacia CAP-Phadiatop test, which detects serum IgE specific to most common airborne allergens, was used. Some of the specific sensitizing allergens were also identified by the related CAP-RAST method. Sensitization was detected in 223 of the 505 subjects (44.2%) screened. Kuwaiti nationals had a significantly higher prevalence rate (50.2%) than non-Kuwaitis (34.2%) (chi 2 = 8.6, P < 0.003). The highest prevalence rate was found among male Kuwaitis (53.8%). The prevalence of current or previous allergic disease (subject-reported) was 20.6%. Bermuda grass, house-dust mite (Dermatophagoides pteronyssinus), and Chenopodium album were the most prevalent sensitizing allergens, with frequencies of 53.6%, 52.7%, and 50.9%, respectively, among the sensitized subjects (corresponding to 23.7%, 23.3%, and 22.5%, respectively) for the entire population. Sensitization increased with age, but only among the expatriates, younger Kuwaitis being as frequently sensitized as the older ones. Polysensitization was found to be common. Of the 109 CAP-RAST-positive subjects, 71 (65.1%) were sensitized to more than one allergen, and 30 of these (42.3%) were sensitized to four or more allergens. These results show that atopy is highly prevalent among young adults in Kuwait, and the higher prevalence rate among nationals than expatriates suggests the involvement of genetic or local environmental factors. The results also confirm that mite and plant pollens may be major sensitizing allergens even in a desert environment.

Adolescent↗

The reduction of rhinitis symptoms by nasal filters during natural exposure to ragweed and grass pollen.

BACKGROUND: Prototype nasal filters were developed to collect inhaled pollen. This study evaluated the efficacy of the filters for prevention of rhinitis symptoms during acute outdoor pollen exposure. METHODS: A randomized double-blind design was used. Subjects (n=46) with a history of autumn exacerbation of rhinitis and positive skin test to ragweed, Bermuda and/or Bahia grass wore either active or placebo nasal filters for 2 h in autumn in a park containing these species. Major and Total Symptoms scores were recorded at 0, 30, 60, 90 and 120 min. RESULTS: Subjects wearing active nasal filters had significantly reduced scores, at all time-points compared with placebo group (all P <0.05). Of 14 individual symptoms measured, seven were significantly reduced (number of sneezes, runny nose, itchy nose, sniffles, itchy throat; itchy eyes and watery eyes) and another three showed a trend towards lower severity. The nasal filters also enabled the resolution of existing symptoms. Maximal difference in symptoms was seen immediately after subjects had spent 20 min sitting beside a large patch of ragweed. CONCLUSION: This is the first clinical trial of a nasal filter. The results suggest it has potential for enhancing rhinitis management during acute allergen exposure.

Adolescent↗

Annual cycles of solar insolation predict spawning times of Caribbean corals.

Seasonal increases in sea surface temperature (SST) have long been considered the trigger for mass spawning events in reef corals. We critically examined the relationship between SST and the spawning activity of broadcasting corals in the tropical western Atlantic (Caribbean). This meta-analysis examined 12 species of broadcasting corals at 25 sites spanning 22 degrees of latitude (10 degrees-32 degrees N) from Venezuela to Bermuda in the Atlantic Ocean from 1986 to 2004. Sigmoidal logit regression models were used to examine the relationship between the release of reef-coral gametes and the environmental variables SST and solar insolation defined as (1) the cumulative response 7-10 months prior to spawning (integral); (2) the rate of change at the time of spawning (derivative); and (3) the average for the month of spawning. The Quasi-Newton method was used to estimate the maximum likelihood of the response function. We demonstrate that the recent history and rate of change in temperature correlate poorly with the timing of spawning, while the average temperature during the month of spawning was significant (with all corals releasing gametes 28-30 degrees C, except Montastraea annularis, which released gametes at 27-30 degrees C). In contrast, the rate of change and the cumulative response of solar insolation cycles was a better predictor of gamete release, but solar insolation intensity at the time of spawning was not. These models have important implications for predicting coral reproductive cycles in all oceans, and for examining other marine phototrophic systems beyond corals.

Animals↗

Effects of diet and feeding on postprandial serum gastrin and insulin concentration in adult horses.

Gastrin is the only hormone known to stimulate secretion of hydrochloric acid. It also has trophic effects on specific parts of the mucosa of the gastrointestinal tract. Using radioimmunoassay techniques, postprandial serum gastrin and insulin concentrations were measured in six adult horses to establish effects of different diets on gastrin concentrations. Insulin concentrations were measured to provide support to the patterns of gastrin secretion because patterns of insulin secretion were already known. The horses were fed coastal bermuda hay, or twice daily 5 kg of a complete pelleted ration, 5 kg of commercial sweet feed or 5 kg of the sweet feed together with hay. There was little change in serum gastrin or insulin concentrations after feeding hay alone. Rations containing more readily available nutrients (pellets, sweet feed) produced significant increases in postprandial serum gastrin and insulin concentrations. Gastrin concentrations also varied according to the duration of feeding each diet, but this was not seen with insulin. These results indicated that gastrin secretion, and therefore possibly gastric acid secretion, were markedly influenced by dietary composition and duration of feeding a diet. There appeared to be some adaptation of the stomach (gastrin secretion) to changes in diet, but this was not accompanied by indications of adaptation in the endocrine pancreas (insulin secretion).

Animals↗

Comparison of age, sex, breed, history and management in 229 horses with colic.

A study, at a university in south eastern USA, aimed to determine whether age, sex, breed, management and history differed in colic cases. A detailed history was obtained for 229 horses between January 1987 and June 1988. Causes for colic determined by clinical examination, exploratory laparotomy and/or necropsy included: gastric rupture (GR, 6); ileal impaction (II, 17); small intestinal strangulating obstruction (SIO, 22); proximal enteritis (PE, 16); transient small intestinal distension (TSID, 18); large colon displacement (LCD, 52); large colon impaction (LCI, 34); colitis (8); small colon obstruction (SCO, 7); peritonitis (7); and unknown (42). Prevalence of age, sex, breed and use, type and amount of grain and roughage fed, supplement feeding, diet change within 30 days, stocking density, deworming rate and routine, and previous colic were determined in each category and compared by multiple regression and chi-square analysis (P < 0.05). The PE group included a greater proportion of horses aged five to 10 years (68.8 per cent) and stallions (37.5 per cent) than other categories. Most horses with II were under five years. Horses under one year were most prevalent in SIO (22.7 per cent) and SCO (28.6 per cent), and those of 15 years or more were most prevalent in SCO (57.1 per cent) and GR (50 per cent). Quarterhorses comprised 48.1 per cent of the LCD group and there was a high incidence of Arabians in groups with II (29.4 per cent) and TSID (27.8 per cent). Pelleted grain was associated with LCD. Prevalence of Bermuda grass hay feeding was less in PE and SCO groups, and pelleted roughage was associated with LCI. Showing and racing/training the day before colic were associated with LCD and LCI, respectively. There was no dietary association with II development and no correlation between use, amount of grain or hay fed, type of pasture, deworming or history of previous colic and various causes for colic.

Aging↗

Induction and maintenance of gastric ulceration in horses in simulated race training.

Gastric ulceration is a prevalent condition of racehorses. A number of models of gastric ulceration have been described, but none mimic the conditions of a horse in training. The objectives of this study were to determine whether gastric ulcers could be induced and maintained in a group of horses in simulated race training. In addition, serum cortisol was measured on a weekly basis to investigate the possibility that stress may be important in the pathogenesis of gastric ulceration. Thirty horses used in the trial were fed Bermuda grass hay and 6 kg of a concentrate diet, and exercised 6 days/week at speed over a distance of 1.6-2.4 km. Serum was collected and gastroendoscopic examinations performed on a weekly basis for the duration of the trial. All horses developed moderate to severe ulceration, and ulcers were maintained for the 56 day period of the trial. Only one horse had signs of abdominal discomfort, which resolved with minimal symptomatic treatment and without the use of anti-ulcer medications. Serum cortisol remained within reference ranges for the duration of the trial. Although there was some variation between the weekly examinations, serum cortisol concentrations were decreased from values obtained at the start of the trial. In this study ulcers developed without the administration of nonsteroidal anti-inflammatory agents or withholding of feed. This model provides a method to study the condition, and to investigate the effects of medications on the healing of ulcers in racehorses.

Analysis of Variance↗

The 20-Hz signals of finback whales (Balaenoptera physalus).

The 20-Hz signals of finback whales (Balaenoptera physalus) were analyzed from more than 25 years of recordings at a variety of geographic locations on near-surface hydrophones close to whales and on deep hydrophone systems. These signals were composed of 1-s pulses of sinusoidal waveform with downward sweeping frequency from approximately 23 to 18 Hz at variable source levels up to 186 dB (re: 1 microPa at 1 m), usually with slightly lower levels for the pulses at the beginning and end of sequences. These "20-Hz" pulses were produced in signal bouts (separated by more than 2 h) lasting as long as 32.5 h. Bouts were composed of regularly repeated pulses at intervals of 7-26 s (typically), either at one nominal pulse rate or at two alternating (doublet) pulse intervals. Signal bouts were interrupted by rests of 1-20 min at roughly 15-min intervals and by irregular gaps lasting between 20 and 120 min. The distribution of these signals throughout the year and their temporal sequence were analyzed from the continuous drum records of the Bermuda SOFAR Station. Signal bouts occurred during winter, sometimes beginning in September and ending in May. The sound sequences were never exactly replicated. Direct association of the bouts with the reproductive season for this species points to the 20-Hz signals as possible reproductive displays by finback whales.

Acoustics↗