Occurrence of unstable PEP carboxylase in C4 grasses in the genus Spartina Schreb.

Abstract The aims of this work were to discover the distribution within the C₄ grass Spartina anglica of a PEP carboxylase which is very unstable during and after extraction, and to determine whether this unstable form occurs in other members of the genus. In S. anglica, only the leaf contains an unstable PEP carboxylase. Within the leaf only the major one of two isoenzymes is unstable, and this is located in the mesophyll cells. The unstable isoenzyme is inactivated during extraction and storage unless protected by bovine serum albumin or Triton X-100, and is inactivated in assay mixtures at optimum pH in the absence of PEP. Evidence is presented that inactivation is not due to degradation or inhibition during extraction and storage. The enzyme from leaves of Spartina species taxonomically closely related to S. anglica is also very unstable during and after extraction, but that from less closely related species is much more stable.     

Radio-Tracking Timber Wolves in Ontario

Miniature collar-type transmitters originally designed by W.W. Cochran, Illinois, were adapted for use on timber wolves(Canis lupus sp.) in east-central Ontario. Wild timber wolveswere captured in steel traps, restrained with a forked stick,fitted with radio-collars and released at point of capture.Receivers were adapted for use in trucks, airplanes, and forwalking in rough bush country. Maximum ranges were 3.2 km withground and 9.6 km with aircraft receivers. A preadult femaletagged in July, 1964, and a lactating adult female tagged inJune, 1965, were tracked intermittently for 5.5 and 2.5 months,respectively. Tracking periods for six other animals of bothsexes, ranging in age from pups to adults, varied from 2 daysto 4 months. The lactating female and her associated pack regularlyreturned to three preferred "resting sites" for various periodsduring July and August. Preferred areas were well drained, semi-open,mixed conifer-hardwood stands in close proximity to swamps orbeaver ponds. The preadult female ranged in an area frequentedby a pack, but frequently remained independent of it. A preadultmale, tagged in the same region, wandered over a slightly largerarea than the female. Tagged animals were active throughoutall periods of the day or night. Activity increased slightlyduring the early evening hours. There was a slight correlationbetween weather conditions and patterns of behavior and activity.Apparently, tagged individuals were quickly accepted by othermembers of the pack.     

Identification and characterization of simple sequence repeat markers from Brassica napus expressed sequences

The availability of expressed sequence data derived from gene discovery programs enables mining for simple sequence repeats (SSR), providing useful genetic markers for crop improvement. These markers are inexpensive, require minimal labour to produce and can frequently be associated with functionally annotated genes. This study presents the development and characterization of 24 expressed sequence tags (EST)‐SSR markers from Brassica napus and their cross‐amplification across Brassica species. The markers show reliable amplification, genome specificity and considerable polymorphism, demonstrating the utility of EST‐SSRs for genetic analysis of wild Brassica populations and commercial Brassica germplasm.     

White Ethnogenesis and Gradual Capitalism: Perspectives from Colonial Archaeological Sites in the Chesapeake

The piecemeal development of capitalist socioeconomic systems in the colonial Chesapeake was deeply intertwined with projects of white ethnogenesis. Crafting a sense of "groupness" along lines perceived as racial required free "whites" to remain economically and socially interdependent. A variety of strategies and material forms—including reciprocal exchanges, hall-parlor house plans, and earthfast construction—facilitated this cohesion. Such integrative tactics coexisted in colonists' behavioral repertoires with more "capitalistic" strategies that prioritized private profit over social obligation. Colonists' deployment of diverse social strategies reflects a complex calculus assessing the benefits of economic autonomy against the benefits of ethnic ("white") solidarity. These dynamics can be illustrated through an 18th-century archaeological site at Flowerdew Hundred in the Chesapeake.     

Accumulation and subcellular distribution of cations in relation to the growth of potassium-deficient barley

Abstract Growth of barley (Hordeum vulgare L., cv. Georgie) was insensitive to soil K content above about 150 mg kg^?1, but at lower levels it declined. The reduction in yield was greater in soils containing approximately 10 mg Na kg^?1 than in soils with about 90 mg kg^?1 of Na. Growth was unaffected by changes in shoot K concentration above 75 mol m^?3, but declined at lower concentrations, and the decrease was less in plants grown in soils with high Na. Growth responses were not simply related to tissue K concentrations because plants grown in soils with extra Na had higher yields but lower K concentrations. When soil Na was low, plants accumulated Ca as tissue K declined, but when Na was provided this ion was accumulated. Plant Mg concentrations were generally low but increased as K decreased. The Ca and Mg were osmotically active. There were highly significant inverse linear relationships between yield and either the Ca or Mg concentrations in the shoots. X-ray microanalysis was used to examine the compartmentation of cations in leaves from barley plants (cv. Clipper) grown in nutrient solutions with high and low K concentrations. In plants grown with 2.5 mol m^?3 K, this was the major cation in both the cytoplasm and vacuole of mesophyll cells. However, in plants grown with 0.02 mol m^?3 K it declined to undetectable levels in the vacuole, although it was still detectable in the cytoplasm. In all plants, Ca was mainly located in epidermal cells. The implication of the results for explaining responses to K. in terms of compartmentation of solutes is discussed.