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How well are you teaching one of the most important biological concepts for humankind? A call to action

We represent several generations of biology educators – with teaching experiences beginning in the 1940s and continuing to the present, from elementary school to graduate-level programs. We find the vast array of subjects that biology teachers can now cover both thrilling and mind-boggling. Depending on the grade level, units exist that focus on neurobiology, forensics, DNA analysis, biotechnology, marine biology, and a host of other topics. Although science teachers cover a potpourri of advanced topics, we must ask ourselves – no matter our biology-teaching responsibilities – how well we are teaching carrying capacity , one of the most fundamental biological concepts for our society, knowledge of which becomes more important every day. As biology teachers, most of you know that carrying capacity is defined as the maximum population an environment can sustain, given the amounts of food, habitat, and other resources available. Every environment – from your goldfish bowl to the local forest to planet Earth – can only sustain a set number (weight) of a particular species, based on available resources and space. Currently, most science classes teach …

The American Biology Teacher

Introduction of translation stop condons into the viral glycoprotein gene in a fish DNA vaccine eliminates induction of protective immunity

A highly efficacious DNA vaccine against a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), was mutated to introduce two stop codons to prevent glycoprotein translation while maintaining the plasmid DNA integrity and RNA transcription ability. The mutated plasmid vaccine, denoted pIHNw-G2stop, when injected intramuscularly into fish at high doses, lacked detectable glycoprotein expression in the injection site muscle, and did not provide protection against lethal virus challenge 7 days post-vaccination. These results suggest that the G-protein itself is required to stimulate the early protective antiviral response observed after vaccination with the nonmutated parental DNA vaccine.

Marine Biotechnology

A reverse genetics system for the Great Lakes strain of viral hemorrhagic septicemia virus: the NV gene is required for pathogenicity

Viral hemorrhagic septicemia virus (VHSV), belonging to the genus Novirhabdovirus in the family of Rhabdoviridae , causes a highly contagious disease of fresh and saltwater fish worldwide. Recently, a novel genotype of VHSV, designated IVb, has invaded the Great Lakes in North America, causing large-scale epidemics in wild fish. An efficient reverse genetics system was developed to generate a recombinant VHSV of genotype IVb from cloned cDNA. The recombinant VHSV (rVHSV) was comparable to the parental wild-type strain both in vitro and in vivo, causing high mortality in yellow perch ( Perca flavescens ). A modified recombinant VHSV was generated in which the NV gene was substituted with an enhanced green fluorescent protein gene (rVHSV-ΔNV-EGFP), and another recombinant was made by inserting the EGFP gene into the full-length viral clone between the P and M genes (rVHSV-EGFP). The in vitro replication kinetics of rVHSV-EGFP was similar to rVHSV; however, the rVHSV-ΔNV-EGFP grew 2 logs lower. In yellow perch challenges, wtVHSV and rVHSV induced 82-100% cumulative per cent mortality (CPM), respectively, whereas rVHSV-EGFP produced 62% CPM and rVHSV-ΔNV-EGFP caused only 15% CPM. No reversion of mutation was detected in the recovered viruses and the recombinant viruses stably maintained the foreign gene after several passages. These results indicate that the NV gene of VHSV is not essential for viral replication in vitro and in vivo, but it plays an important role in viral replication efficiency and pathogenicity. This system will facilitate studies of VHSV replication, virulence, and production of viral vectored vaccines.

Marine Biotechnology

Tissue-specific induction of Hsp90 mRNA and plasma cortisol response in chinook salmon following heat shock, seawater challenge, and handling challenge

In studying the whole-body response of chinook salmon ( Oncorhynchus tshawytscha ) to various stressors, we found that 5-hour exposure to elevated temperature (mean 21.6°C; + 10.6°C over ambient) induced a marked increase in Hsp90 messenger RNA accumulation in heart, brain, gill, muscle, liver, kidney, and tail fin tissues. The most vital tissues (heart, brain, gill, and muscle) showed the greatest Hsp90-mRNA response, with heart tissue increasing approximately 35-fold. Heat shock induced no increase in plasma cortisol. In contrast, a standard handling challenge induced high plasma cortisol levels, but no elevation in Hsp90 mRNA in any tissue, clearly separating the physiological and cellular stress responses. We saw no increase either in tissue Hsp90 mRNA levels or in plasma cortisol concentrations after exposing the fish to seawater overnight.

Marine Biotechnology