Vertical distribution and diel vertical migration of krill beneath snow-covered ice and in ice-free waters.

A bottom mounted upward looking Simrad EK60 120-kHz echo sounder was used to study scattering layers (SLs) and individuals of the krill . The mooring was situated at 150-m depth in the Oslofjord, connected with an onshore cable for power and transmission of digitized data. Records spanned 5 months from late autumn to spring.

Application of blocking oligonucleotides to improve signal-to-noise ratio in a PCR.

"Universal" or group-specific PCR primers have a tendency to predominately hybridise with the common sequences in samples with mixed templates. The result is that the rarer sequences are seldom retrieved by cloning or sequencing. The use of a blocking oligonucleotide (oligo) designed to specifically prevent amplification of dominant or unwanted DNA templates is an easy way to improve the amplification of rarer sequences.

Vertical migration, feeding and colouration in the mesopelagic shrimp Sergestes arcticus.

Intraspecific variation in vertical distribution, timing of vertical migration, and colouration of the mesopelagic shrimp Sergestes arcticus were studied in the >400 m deep part of Masfjorden, Norway. Very few individuals were caught in the upper strata during daytime, and larger individuals occurred deeper during the day than smaller ones. Vertical migration was prominent and no overall trend of increasing length with depth was found at night.

Blocking primers to enhance PCR amplification of rare sequences in mixed samples - a case study on prey DNA in Antarctic krill stomachs.

Background: Identification of DNA sequence diversity is a powerful means for assessing the species present in environmental samples. The most common molecular strategies for estimating taxonomic composition depend upon PCR with universal primers that amplify an orthologous DNA region from a range of species. The diversity of sequences within a sample that can be detected by universal primers is often compromised by high concentrations of some DNA templates.