No abstract

We report the cloning, overexpression, kinetic analysis, and modeling of the tertiary structure of an unusual plant cysteine proteinase. Ananain (EC 3.4.22.31), from Ananas comosus (pineapple) is distinguished from all other cysteine proteinases in the papain superfamily by having a unique combination of acidic amino acids. As well as lacking the acidic residue immediately preceding the active site histidine (position 158 in papain), it also lacks the extensive surface network of acidic residues that were postulated to compensate for the loss of charge at position 158 in mammalian cathepsins. Ananain has the fewest acidic residues, so far reported, of any plant cysteine proteinase, but two of the carboxyl residues (E50 and E35) postulated to have an enabling role in catalysis, the so-called "electrostatic switch", remain conserved. Comparisons of the kinetics of recombinant wild-type ananain with E50A and E35A mutants proves that these charged groups are not essential for catalysis. Hence this research does not confirm the presence of an electrostatic switch in this cysteine proteinase, and the role of acidic residues in the enhancement of catalytic competence in these enzymes is discussed in light of this new evidence.

The tissue-specific and developmental expression of histone 2A was studied in onion (Allium cepa ' Robusta '), using northern blots. Histone 2A expression was enriched in basal tissues, particularly in the inner, meristematically active parts of bulbs. The expression was assessed during a time course of bulb development, dormancy onset and post-harvest sprouting in field-grown material. During bulb development histone 2A expression in the inner bulb declined rapidly during bulb ripening, reaching a minimum with the onset of dormancy. During post-harvest storage, expression increased slowly, reaching a peak in the spring, coinciding with the first observed sprout emergence. It was concluded that in onion, as in other plant systems, histone 2A expression is linked to cell division and dormancy level, the peak in expression during post-harvest storage indicating the time of dormancy breakage. In cultivars where post-harvest sprouting occurred much earlier or much later than in ' Robusta ', this expression peak occurred at about the same time of year, regardless of sprouting time. It was concluded that differences in storage longevity between cultivars were not due to differing times of dormancy breakage. Factors controlling the rate of sprout emergence post-dormancy are likely to be major determinants of storage capacity.

A major review of research in marital happiness in the decade [1960][1961][1962][1963][1964][1965][1966][1967][1968][1969][1970] concluded that:In general, higher occupational statuses, incomes, and educational levels for husbands; husband-wife similarities in socio-economic status, age, and religion; affectional rewards, such as esteem for spouse, sexual enjoyment, companionship; and age at marriage had all been delineated as variables correlated positively with marital happiness. Non-whites have different and essentially less happy marriages. It should be noted, of course, that at best these variables accounted for less than one-third of the variance in marital happiness. [Hicks and Platt, 1971: 555] ]The search for theory and/or models in the broad area of family interaction continues unabated as we enter the second half of a subsequent decade. Central to the problem of articulating the processes and patterns of interaction between spouses, parents and children, and siblings is the inadequacy of much of the existing instrumentation in terms of sensi-AUTHORS' NOTE: