Effects of Different Photoperiods and Chilling Treatments on Growth and Reproduction of Cardamine flexuosa With. and Its Ecological Implications

Abstract Phenotypic variability of Cardamine flexuosa (Cruciferae) was examined in response to different lengths of exposure to low temperature (5°C) at the juvenile stage, and to two photoperiod regimes (8 and 16 hrs day-lengths) in the subsequent growth period. The results indicated that this species had a facultative chilling or long-day requirement for flowering. The long-day and chilling treatments both caused an earlier onset of stem internode elongation. Longer chilling treatments reduced the number of nodes and increased internode length under both long and short photoperiod regimes. Prolonged chilling treatments followed by long-day photoperiod remarkably induced more numerous basal branches and inflorescences, as a result producing more siliques. Remarkable rosette leaves Were formed at the base of the main stem when partial chilling and the short-day treatment suppressed stem internode elongation. The responses to chilling and long-day treatment closely resembled the synchronized flowering of this species in spring in the field. Delayed flowering under the short-day treatment resembled size- or age-dependent flowering in late summer to autumn in the field populations.     

THE SURFACE EVENTS AT FERTILIZATION OF THE SEA URCHIN EGG I. EVENTS ON THE SURFACE OF THE VITELLINE COAT1

Sperm-egg interaction during normal fertilization in the sea urchins, Strongylocentrotus intermedius and Hemicentrotus pulcherrimus, was studied by scanning and transmission electron microscopy. Several seconds after insemination, acrosome-reacted spermatozoa were found attached to the surface of the vitelline coat on each egg. Soon, several bulges of the vitelline coat appeared surrounding the fertilizing spermatozoon. These bulges then spread over the surface increasing in number, while they became fewer and disappeared around the sperm head. Thin sections of the bulging areas revealed discharging cortical granules. As the bulging vitelline coat was elevated, the sperm head was incorporated into the perivitelline space, passing through a small hole in the coat that resulted from penetration of the sperm acrosomal process immediately before fusion of the gametes. When the spermatozoon disappeared beneath the fertilization membrane, a hole was left in the membrane and the cortical reaction had finished on the other hemispheric surface. Mechanical removal of the membrane at that time exposed a spermatozoon protruding perpendicularly from the egg plasma membrane surface. The anterior tip of the sperm head was smoothly connected with the egg surface, and neither microvillous projections nor cytoplasmic covering of the egg cytoplasm could be found around the spermatozoon.     

Inhibitory Action of Blue and Far-Red Light in the Flowering of Lemna paucicostata

In a new strain of short-day duckweed (Lemna paucicostata T-101), blue and far-red light-induced inhibition of flowering was investigated. Flowering of this strain failed to be induced under a short-day photoperiod of blue and far-red light, although it responded as a typical short-day plant in red and white light. When the short-day photoperiod of blue or far-red light was terminated by a 15 min red light pulse, flowering recovered completely. This inducing effect of red light was reversed by subsequent exposure to far-red light. Furthermore, it could be demonstrated that 30 min of blue light completely reversed the flowering inductive effect of 5 min red light and vice versa. Evidence is presented suggesting that the inhibitory action of blue and far red light may be due to the lowering of phytochrome P_fr levels below those required to start the dark reactions which lead to flowering. These results are discussed in relation to the time measurement system of photoperiodism.     

Rhyncholites and conchorhynchs as calcified jaw elements in some late Cretaceous ammonites

Conspicuous calcareous coverings are present in the anterior region of 17 fossil jaws from late Cretaceous rocks of Hokkaido (Japan) and Sakhalin (U.S.S.R.). The jaws were preserved in calcareous nodules either in situ in body chambers of ammonites or in close association with identifiable ammonite conch remains. From the morphologic similarity between in situ and isolated jaws, they may be attributed to Tetragonites glabrus, Gaudryceras tenuiliratum, G. denseplicatum, G. sp., and Neophylloceras subramosum. The jaw apparatus of these species is composed of two three-dimensional black walls of carbonate apatite, which might be a diagenetic replacement of chitinous material. The calcareous coverings in both upper and lower jaws closely resemble those of upper (rhyncholite) and lower (conchorhynch) jaws of modern Nautilus as well as rhyncholite and conchorhynch fossils in their gross morphology, microstructure, and chemical composition. Calcified remains of cephalopod jaws known as rhyncholites and conchorhynchs have been reported from late Paleozoic to Recent. The present discovery of ammonoid rhyncholites and conchorhynchs suggests that at least some previously known late Paleozoic and Mesozoic counterparts belong to the Ammonoidea. The essential similarity of jaw elements of some Late Cretaceous ammonites and modern Nautilus gives reliable information on the feeding habits of the former. The sharp and thick ammonoid rhyncholites and conchorhynchs may have had a special function for cutting up food, similar to those of Nautilus.     

Auxin-induced growth of tuber tissue of Jerusalem artichoke IV. Significance of gibberellin biosynthesis and basic proteins in chromatin in aging process

The role of endogenous gibberellin in the aging process preparatoryto auxin action of expanding cells was studied, using tissueslices excised from cold-stored Jerusalem artichoke tuber. CCC inhibited the auxin-induced expansion growth when addedto slices during the aging period. This inhibition was alleviatedby the simultaneous addition of gibberellic acid. The amountof gibberellin-like substances increased during the aging periodand this increase was suppressed by CCC. During the aging period, acid-soluble basic proteins in thechromatin fraction decreased in amount, and exogenous gibberellicacid enhanced the decrease. (Received October 30, 1967; )     

Taxonomic identity of a galling adelgid (Hemiptera: Adelgidae) from three spruce species in Central Japan

Gall‐forming insects are commonly highly host‐specific, and galling species once thought to be oligo‐ or polyphagous are often found to represent a complex of host‐specific races or cryptic species. A recent DNA barcoding study documented that an unidentified species of the genus Adelges is a gall‐former associated with four spruce species (Picea bicolor, P. koyamai, P. maximowiczii, P. polita) as the primary hosts, with little genetic differentiation among insects on different host species. In this study, we investigated the morphology of this galling adelgid to determine its taxonomic identity. Morphological inspection of insects collected from three of the spruce species confirmed that this adelgid is a single galling species, and is identified as Adelges (Sacchiphantes) kitamiensis, which was previously known only from the secondary host. We described the gallicola adults of this species, as well as the first‐instar exules which are the offspring of gallicolae. Finally, we verified the taxonomic identity of this species and discuss its life cycle and host distribution.     

RIBONUCLEIC ACID METABOLISM AND CELL EXPANSION IN OAT COLEOPTILE

RNA metabolism in oat coleoptiles was studied using physiologicalresponses to 5-FU and actinomycin D; autoradiographic detectionof RNA and protein synthesis; and estimation of ribosomal concentrationby analytical ultracentrifugation. 5-FU failed to inhibit growthof either intact coleoptiles or isolated coleoptile segmentsbut completely blocked cell division in roots. Actinomycin Dmarkedly inhibited auxin-induced expansion of coleoptile segments.When supplied to isolated segments from coleoptiles of variouslengths the RNA precursors cytidine, adenine and adenosine allshowed weak incorporation into RNA of nuclei and in some cases,to a lesser extent, RNA of cytoplasm. IAA did not affect thisRNA synthesis but it was considerably reduced by actinomycinD. A proportion of the label incorporated from RNA precursorswas not removable with either RNase, PCA or hot TCA but wasextracted by trypsin. The amount of this spurious incorporationincreased with coleoptile age, as did the ability to incorporatelabelled amino acids. The concentration of both free and boundribosomes does not increase in growing coleoptiles and may evendecline. Free ribosomes decline markedly in fully grown coleoptileswhile the proportion of bound ribosomes increases. It is concludedthat young coleoptiles contain a full complement of ribosomesnecessary for subsequent growth but normal growth is dependenton continued production of an actinomycin D-sensitive messenger-typeRNA. No evidence for auxin mediation of RNA synthesis was found. ¹Present address: Laboratory of Cell Biology, Faculty of Science,Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka, Japan.