Changes in the Envelope Permeability of Developing Chloroplasts

The distribution of ³H-labelled mevalonic acid, leucine andtyrosine between plastids and extraplastidic tissue in illuminated,etiolated seedlings was studied using electron microscope autoradiomicrographyand radioassay of specific plastidic and extraplastidic components.There appears to be a selective change in the permeability ofthe plastid envelope during development which differs accordingto the specific substrates used.     

Low oviposition stimuli reduce egg production in the pollen beetle Meligethes aeneus

Abstract. Gravid female pollen beetles, Meligethes aeneus (F.) (Coleoptera: Nitidulidae), were exposed at different intervals to oviposition sites that varied in acceptability.The egg load of dissected individuals which had been deprived of oviposition sites was not greater than individuals which had been frequently exposed to oviposition sites.However, the egg load of individuals which had been exposed to highly acceptable host plants was greater than those exposed to a host plant of low acceptability.Over the experimental period the total number of eggs which an individual produced was lower for those that were either deprived of an oviposition site or frequently exposed to a low-quality host plant.There was no evidence of either increased oviposition probability or clutch size as the period since the last oviposition increased.It is concluded that low host quality and low host encounter rate reduce the egg production of M.aeneus. It is further concluded that the suppressed egg production reduces the accumulation of eggs, so that physiological motivation for the insect to oviposit is not increased.If low oviposition site quality acts to reduce oogenesis, as found here, then the probability of egg deposition on low-quality species may not increase over time and the effect of antixenotic resistance may be enhanced.     

Biology and control of the sciarid Lycoriella auripila Winn. (Diptera: Lycoriidae) in mushroom culture

The life-history of L. auripila, as a pest of mushrooms, is outlined and an explanation is given of the different types of damage caused. The most satisfactory control is based on the incorporation of insecticides in compost at spawning. Emulsions of chlorfenvinphos and diazinon at 50 ppm are lethal to young larvae for at least 7 weeks but granular formulations of the former must be applied at 100 ppm to achieve comparable results. Drenches of 0–01% malathion, applied at about 40 gal/1000 ft², are effective against larvae in the casing.     

H-Y Antigen and Sex-Determination in Turtles

H-Y antigen was investigated in 14 turtle species belonging to five different families. In 13 species the female was typed as H-Y antigen positive, only in Chinemys reevesi was the male H-Y antigen positive. Since in all vertebrate species studied till now, the expression of H-Y antigen is strictly correlated with the heterogametic sex, it can be assumed that in turtles both types of sex determining mechanisms are realized, namely the ZZ/ZW-and the XX/XY mechanism; both mechanisms are realized in species belonging to one and the same turtle family. However, most turtle species seem to be endowed with a ZZ/ZW sex determining mechanism.     

On the Proteaceae—the evolution and classification of a southern family*

A scheme of phylogeny in the Proteaceae is derived from analysis of new and previously available data on morphological, anatomical and chromosomal characters. The probable attributes of a common ancestor are indicated and it is concluded that the family has no close relatives, although it possibly diverged early from the Rosiflorean line. Chromosomal evolution has been complex, with early polyploidy, repeated dysploid reductions and great change in chromosome size, from a probable base of x = 7. Habit, wood anatomy, leaf form and sequence, chemical features, inflorescences, pollination and pericarp anatomy are discussed in relation to adaptation, phylogeny, parallelism and convergence. Distribution is analysed ecogeographically and in relation to the fossil record and chronology of continental movement. Ancestors of major groups may have differentiated before the break-up of Gondwanaland. Early members of almost all tribes were probably trees of mesothermic closed forests; xeromorphic characters found in many modern genera are secondary and of multiple origin in Australia, South Africa, New Caledonia and to a lesser degree in South America. The Proteaceae, with 75 genera, are divided into 5 subfamilies (3 new) comprising 14 tribes, further subdivided into 33 units of subtribal level. New genera described are Toronia, Acidonia, Pycnonia, Triunia, Malagasia, Athertonia, Virotia, Floydia.     

Predictions of Backbone Conformational Changes in Abnormal Haemoglobins

THE structural effects of amino-acid residue replacement in some thirty-five mutant haemoglobins have been discussed by Perutz and Lehmann¹, who consider the perturbations which side-chains of different size, shape and charge introduce into the normal local stereochemistry.