Adjacivena rasnitsyni gen. n., sp. n., from the Middle Jurassic Jiulongshan Formation (Daohugou Village, Inner Mongolia,
China), is described based on a set of well-preserved specimens, interpreted as two females and a male of the same species. The new
taxon is assigned to the family Susumaniidae, i.e. is a candidate stem-Phasmatodea. This ordinal assignment is supported by genital
elements, chiefly a putative operculum concealing the ovipositor observed in one female specimen and a putative extension of the
10th tergum with a thorn pad in the male specimen. Variation in the venation of the forewing is appreciated based on more or less
complete pairs of wings and a comparison with that in the forewings of male Heteropteryx dilatata (Parkinson, 1798). This material
offers new perspectives on the primary homologies of the hind wing venation of stick-insects.
The activity of photosystems (PS) 1 and 2, together with the content and ratio of photosynthetic pigments, were measured in three inbred lines and two F1 hybrids of maize (Zea mays L.), grown in either optimum or low temperature (LT) conditions. The ability of chilling-stressed plants to deal with the negative effects of long-term exposure to LT and to recover the efficiency of photosynthetic apparatus after their return to optimum temperatures was examined during spring and autumn seasons. The aim was to analyse the possible differences between the rapid and gradual onset of LT on the response of young maize plants to chilling stress. The distinctive superiority of hybrids over their parental lines, found during the exposure of maize plants to LT, was not always retained after the return of chilling-stressed plants to optimum growth conditions. The response of individual genotypes to chilling stress, as well as their ability to recover the photosynthetic efficiency from the cold-induced damage, strongly depended also on the duration and the rapidity of the onset of LT. and D. Holá ... [et al.].
Influence of moderate chilling stress on vascular bundle sheath cell (BSC) and especially mesophyll cell (MC) chloroplasts of mature maize leaves was studied by electron microscopy and stereology. Plants of two inbred lines of maize, differing in their photosynthetic activity, and their F1 hybrids were cultivated during autumn in heated or unheated glasshouse. Generally, chilling temperatures resulted mainly in the decrease in stereological volume density (VD) of both granal and intergranal thylakoids of MC chloroplasts, while the ratio of granal to all thylakoids (granality) was less affected. The VD of peripheral reticulum and plastoglobuli usually increased after cold treatment of plants. The volume of MC chloroplasts usually increased under chilling stress, the shape of the chloroplasts changed only slightly. The ultra-structure of chloroplasts differed between individual genotypes; chilling-stressed hybrid plants showed positive heterosis particularly in the granal thylakoids' VD of MC chloroplasts. and J. Kutík ... [et al.].