We used genetic identification methods to examine the stock composition of subyearling Chinook salmon Oncorhynchus tshawytscha in floodplain wetland and main-stem habitats of the lower Willamette River, Oregon. Using a microsatellite DNA baseline of 13 standardized loci and 30 Columbia River basin populations, we analyzed 280 subyearlings collected in winter and spring 2005-2006 from wetland and main-stem river sites. Genetic stock identification analysis indicated that spring Chinook salmon originating from the Willamette River made up a substantial proportion of the samples and contributed 16-71% to sample mixtures representing the wetland habitat sites. Fall Chinook salmon from lower Columbia River sources were also present and contributed 58% of winter samples. Spring Chinook salmon from lower Columbia River populations were present in both wetland (17%) and river (16%) samples in spring 2005, and subyearlings from summer-fall-run populations in the middle and upper Columbia River contributed to spring wetland samples in 2006 (26%). The results suggest that floodplain restoration projects intended to improve fish habitats during winter and spring periods in the lower Willamette River may benefit Chinook salmon populations from the upper Willamette River, lower Columbia River, and upper Columbia River summer-fall evolutionarily significant units.

For salmon populations in the Columbia River and Snake River basins, many of which are listed under the U.S. Endangered Species Act of 1973, reliable estimates of the proportion of hatchery‐origin adults in spawning areas (p) are needed to assess population status and the genetic and demographic interactions of hatchery‐ and natural‐origin fish. Some hatchery fish receive visible marks, coded wire tags (CWTs), parentage‐based tags (PBTs), or all three. This allows one to identify whether fish recovered after release are of hatchery origin. Parentage‐based tagging involves genotyping hatchery broodstock and uses parentage assignments as “tags” that identify the origin and brood year of their progeny. We derived a maximum likelihood estimator of p and applied it to the 2012 and 2013 carcass survey data for spring–summer Chinook Salmon Oncorhynchus tshawytscha in the South Fork Salmon River, Idaho. Maximum likelihood estimation was also applied to CWT data and, for investigating the importance of expected tag recoveries on precision, to simulated PBT data for fall Chinook Salmon spawning in the Hanford Reach of the Columbia River. Precision of p from maximum likelihood estimation increased with the expected number of tag recoveries in a carcass survey, whether CWTs or PBTs. In the South Fork Salmon River application, there were 340% more PBT recoveries than CWT recoveries, leading to greater precision in release‐specific values of p from maximum likelihood estimation. The maximum likelihood estimation procedure provides fisheries managers a method to design a tagging and sampling program aimed at estimating p, a valuable measure of the potential for interaction of wild‐ and hatchery‐origin fish on the spawning grounds. To design a program for estimating p, we recommend selecting a target level of precision and then choosing a tagging fraction and sampling rate that delivers that precision in the most cost‐effective way. Received August 21, 2015; accepted January 19, 2016 Published online April 27, 2016

The effect of 2,6‐dichlorobenzonitrile (DB) and coumarin on tobacco protoplast development has been studied using a combination of flow microfluorimetry and quantitative fluorescence microscopy. The results indicated that, over the initial period of culture, DB largely inhibited cellulose production at the cell surface, but did not inhibit DNA synthesis or protein accumulation by the protoplasts. Continuous culture of protoplasts in DB resulted in the accumulation of an increased capacity for cellulose synthesis as expressed following the removal of inhibitor. The possible sites of the specific inhibitory action of DB are discussed.

A microfluorimetric procedure, employing the fluorescent stain 33258 Hoechst, has been developed for the investigation of the process of DNA synthesis during the initial stages of culture of tobacco (N. tabacum cv. Xanthi) leaf protoplasts. In this system, the freshly‐isolated protoplasts exhibited a unimodal distribution of nuclear DNA content characteristic of the diploid state. The almost immediate onset of DNA synthesis during culture resulted in a doubling of nuclear DNA levels prior to the first mitoses. Although the majority of the protoplasts subsequently entered into synchronous mitosis and cell division, a proportion of the remainder developed into large polyploid cells. Upon further culture, the polyploid cells became subdivided into clusters of small diploid cells. Measurement of total cell protein and cell volumes during culture indicated that a relationship existed between these parameters and the initiation of mitosis. The significance of these observations is discussed.