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.     

Development of a liquid flow-through system to inhibit browning in callus cultures of guayule (Parthenium argentatum Gray)

Calli of P. argentatum were grown on a newly designed liquid nutrient flow-through system which facilitated the subculturing of calli and delayed browning for 6 weeks. Friable calli were obtained on half-strength Gamborg B5-medium supplemented with 0.05 mgl⁻¹ 2,4-dichlorophenoxyacetic acid. Shoots developed on media supplemented with 0.2 mgl⁻¹ benzylaminopurine but lacking 2,4-dichlorophenocyacetic acid.     

A lethal allele at the putative regulatory locus, cpc-1, of cross-pathway control in Neurospora crassa

Summary A lethal allele at the putative regulatory locus, cpc-1, of cross-pathway control in Neurospora crassa was discovered by genetic analysis. cpc-1 ^j-5 is viable only in the presence of a second mutation, slo, causing slow growth. The detection of a lethal allele at a regulatory locus is a rare event and points to the physiological importance of the regulatory circuit concerned, namely the cross-pathway or general control of amino acid biosynthetic enzymes in lower eukaryotes.     

Apokrine Sekretion der peritrophischen Membran von Chironomus thummi piger Str. (Diptera)

Zusammenfassung Am Beispiel der Larven von Chironomus thummi piger werden die Zellen, die die peritrophische Membran abscheiden, licht- und elektronenmikroskopisch untersucht. Es liegen zwei Zelltypen vor, die einerseits durch ihren Reichtum an granulären E.R.-Schläuchen (ER-Zellen), andererseits durch ihren hohen Gehalt an Mitochondrien (M-Zellen) charakterisiert sind. Die ER-Zellen zeigen Veränderungen, die in vielerlei Hinsicht der klassischen Auffassung der apokrinen Sekretion entsprechen und sich nicht in ein modernes Schema der Sekretionsmorphologie einordnen lassen. Die Zellen gehen im Verlauf der Sekretabgabe weder völlig zugrunde, noch bleiben sie vollständig erhalten. Die M-Zellen, die im Gegensatz zu den ER-Zellen keine Sekretionsgranula besitzen, weisen ähnliche Umwandlungen auf. Das fertige Sekretionsprodukt — die peritrophische Membran — entstammt einmal vorgeformten Sekretionsgranula, zum anderen der umgewandelten, abgeschnürten oberen Zellhälfte. Die peritrophische Membran besteht aus zwei Schichten, wovon die lumenseitige, auf Längsschnitten quergestreifte Lage (Wabentextur) vermutlich aus den Sekretionsgranula hervorgeht und die andere längsgefaserte Lage auf die Umwandlung von Zytoplasma zurückzuführen sein dürfte. Die Mikrovilli der Sekretionszellen sind in keiner Weise für die Strukturierung der Wabentextur verantwortlich.

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On the apocrine secretion in the formation of the peritrophic membrane of chironomus thummi piger Str

Summary Taking the larvae of Chironomus thummi piger as an example, the cells secreting the peritrophic membrane have been investigated with the light- and electron-microscope. Two cell-types can be distinguished which in one case are characterized by abundant rough E.R.-tubules (ER-cells) and in the other case by large quantities of mitochondria (M-cells). The ER-cells undergo changes which in many respects correspond to the individual stages of the classic apocrine secretion, and thus do not fit into a modern scheme of the morphology of secretion. In the course of the discharge of the secretory product the cell neither becomes completely necrotic nor remains totally intact. The M-cells, which do not contain secretion granules like the ER-cells, show similar changes. The final product — the peritrophic membrane — is formed on the one hand by membrane bound secretion granules and on the other hand by the transformed and pinched off upper half of the cell. The peritrophic membrane consists of two layers, the one of which, facing the lumen of the midgut and exhibiting a honey-comb-texture, presumably is formed by the secretion granules, whereas the other layer arises from transformed cytoplasm. The microvilli of the secretory cells are not responsible for the formation of the honey-comb-pattern.

Die Untersuchungen wurden mit Unterstützung durch die Max-Planck-Gesellschaft und die Deutsche Forschungsgemeinschaft durchgeführt.     

Buchbesprechungen

Ohne Zusammenfassung     

Koppelungsdaten aus 159 Familien für AB0, Rh,Gm, Gc und Hp

Ohne ZusammenfassungDirektor: Prof. Dr. G. G. Wendt     

Origin of plantlets and callus obtained from chile pepper anther cultures

Summary Androgenesis occurred from chile pepper (Capsicum annuum L.) anthers incubated in a continuous warm environment (29° C) with continuous light. Forty plantes and embryoids were retrieved from anther cultures and anllyzed for isozyme markers. Of these, 35 exhibited a single allele for markers suggesting microspore origin, while 5 were heterozygous indicating somatic tissue origin. Chromosome numbers were confirmed for 21 plantlets, of which 16 were haploid and 5 were diploid. However, two plants exhibited a single allele for an isozyme marker but possessed the diploid chromosome number, suggesting spontaneous doubling. Anther cultures also produced callus. Nearly 92% of the slow-growing calli sampled were heterozygous for the isozyme marker, suggesting somatic tissue origin. More than 46% of the fast-growing calli exhibited only one allele for the marker, indicating microspore origin. Callus did not regenerate plantlets. The occurrence of both heterozygous and homozygous diploid plantlets from pepper anther cultures has important implications for applied breeding programs.