We have developed a simple procedure for the localized mutagenesis of yeast genes. In this technique the region of interest is first amplified under mutagenic polymerase chain reaction (PCR) conditions. Cotransformation of the PCR product with a gapped plasmid containing homology to both ends of the PCR product allows in vivo recombination to repair the gap with the mutagenized DNA. This procedure is efficient, allows targeting of specific regions for mutagenesis, and requires no subcloning steps in Escherichia coli.

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Patients who underwent genetic tests for familial adenomatous polyposis often received inadequate counseling and would have been given incorrectly interpreted results. Physicians should be prepared to offer genetic counseling if they order genetic tests.

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Yeast introns contain three highly conserved sequences which are known to be required for splicing of pre‐mRNA. Using in vitro mutagenesis, we have synthesized seven point mutations at five different sites in these signals in the yeast actin intron. The mutant introns were then inserted into each of three constructs, which allowed us to assess the consequences both in vivo and in vitro. In virtually every case, we found the efficiency of splicing to be significantly depressed; mature mRNA levels in vivo ranged from 0 to 47% of wild‐type. Surprisingly, the tightest mutations were not necessarily at the sites of nucleolytic cleavage and branch formation; these nucleotides are thus highly preferred, but are not absolutely necessary. Moreover, while particular nucleotides are specifically required for the final step in splicing, i.e. 3′ cleavage and exon ligation, the predominant consequence of mutation within the conserved signals appears to be the inhibition of assembly of the splicing complex.

Fish and other aquatic foods (blue foods) present an opportunity for more sustainable diets 1,2 . Yet comprehensive comparison has been limited due to sparse inclusion of blue foods in environmental impact studies 3,4 relative to the vast diversity of production 5 . Here we provide standardized estimates of greenhouse gas, nitrogen, phosphorus, freshwater and land stressors for species groups covering nearly three quarters of global production. We find that across all blue foods, farmed bivalves and seaweeds generate the lowest stressors. Capture fisheries predominantly generate greenhouse gas emissions, with small pelagic fishes generating lower emissions than all fed aquaculture, but flatfish and crustaceans generating the highest. Among farmed finfish and crustaceans, silver and bighead carps have the lowest greenhouse gas, nitrogen and phosphorus emissions, but highest water use, while farmed salmon and trout use the least land and water. Finally, we model intervention scenarios and find improving feed conversion ratios reduces stressors across all fed groups, increasing fish yield reduces land and water use by up to half, and optimizing gears reduces capture fishery emissions by more than half for some groups. Collectively, our analysis identifies high-performing blue foods, highlights opportunities to improve environmental performance, advances data-poor environmental assessments, and informs sustainable diets.The food system is a major driver of environmental change, emitting a quarter of all greenhouse gas (GHG) emissions, occupying half of all ice-free land, and responsible for three quarters of global consumptive water use and eutrophication 3,6 . Yet, it still fails to meet global nutrition needs 7 , with 820 million people lacking sufficient food 8 and with one in three people globally overweight or obese 9 . As a critical source of nutrition 8,10 generating relatively low average environmental pressures 1,2,11,12 , blue foods present an opportunity to improve nutrition with lower environmental burdens, in line with the Sustainable Development Goals to improve nutrition (Goal 2), ensure sustainable consumption and production (Goal 12), and sustainably use marine resources (Goal 14).Blue foods, however, are underrepresented in food system environmental assessments 13 and the stressors considered are limited 4 such that we have some understanding of GHG emissions 14,15 , but less of others such as land or freshwater use 16 . Where blue foods are included, they are typically represented by only one or a few broad categories (see, for example, refs. 3,17,18), masking the vast diversity within blue food production. Finally, estimates combining results of published life cycle assessments undertaken for different purposes, and consequently using incompatible methodologies 19,20 , cannot be compared reliably. It is therefore critical to examine the environmental performance across the diversity of blue foods in a robust, methodologically consistent manner to serve as a benchmark within the rapidly evolving se...

Compared to a century ago, the world's fishing fleets are larger and more powerful, are travelling further and are producing higher quality products. These developments come largely at a cost of high‐fossil fuel energy inputs. Rising energy prices, climate change and consumer demand for ‘green’ products have placed energy use and emissions among the sustainability criteria of food production systems. We have compiled all available published and unpublished fuel use data for fisheries targeting all species, employing all gears and fishing in all regions of the world into a Fisheries and Energy Use Database (FEUD). Here, we present results of our analysis of the relative energy performance of fisheries since 1990 and provide an overview of the current state of knowledge on fuel inputs to diverse fishing fleets. The median fuel use intensity of global fishery records since 1990 is 639 litres per tonne. Fuel inputs to fisheries vary by several orders of magnitude, with small pelagic fisheries ranking among the world's most efficient forms of animal protein production and crustaceans ranking among the least efficient. Trends in Europe and Australia since the beginning of the 21st century suggest fuel use efficiency is improving, although this has been countered by a more rapid increase in oil prices. Management decisions, technological improvements and behavioural changes can further reduce fuel consumption in the short term, although the most effective improvement to fisheries energy performance will come as a result of rebuilding stocks where they are depressed and reducing over‐capacity.

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