Morphological observation and characterization of the Pseudoregma bambucicola with the scanning electron microscope

Both leica microscopic camera system and scanning electron microscopy was used to observe and characterize the feet, back, abdomen, antennae and mouthparts of the Pseudoregma bambucicola from the bamboo, Bambusa multiplex. The possible functions of all the external morphological characteristics of the P. bambucicola were described and discussed in detail, which offers a basis for further enriching the biology, phylogeny and ecological niche of the P. bambucicola. Moreover, the morphological results should contribute to morphological identification and differentiation of the P. bambucicola from other aphids in the same family.     

Environmentally induced morphological variation in the Barnacle Goose,Branta leucopsis

The environmental conditions to which juvenile barnacle geese (Branta leucopsis) were exposed during growth were found to affect their body size at fledging as well as their final adult body size. Small juveniles showed compensatory growth from the time of fledging up to one year of age, but this did not fully compensate the differences in body size that were established before fledging. The variation in protein content in plants eaten during growth could probably explain the observed body size differences, sometimes of more than 10%, between different categories of adult geese. Our results imply that one cannot infer selection on morphological characters from differences between samples of adult birds from different localities or from different cohorts within a population, without first showing that environmental conditions during growth do not affect the development of the characters under study.     

Morphological mutation of Lentinula edodes mycelium, particularly detectable in the dikaryotic state

A morphological mutation particularly detectable in the dikaryotic state was found in Lentinula edodes. The mutant dikaryon was readily distinguishable from the normal dikaryon by the irregularly branched short hyphae, very slow hyphal growth, and sparse aerial hyphae. Genetic analysis revealed that expression of this mutation was controlled by a single recessive gene, mor-13. Linkage analysis showed that the mor-13 was not linked to either the incompatibility factors (A and B) or the five kinds of mor genes that were segregated independently of each other in a previous study. Contribution no. 380 from the Tottori Mycological Institute     

Morphological consequences of the trade-off between growth and reproduction in a columnar cactus (Lophocereus schottii)

Since cacti have very small surface/volume ratios, the amount of light they intercept is limited, and so is photosynthesis. However, many cacti shade themselves by means of dense hairy mats, called cephalia, which protect the floral buds. There is a trade-off between allocating a surface to photosynthesis or to the protection of reproductive structures. We found that proportion of the stem covered by cephalium affected fitness in the columnar cactus Lophocereus schottii. Too little cephalium holds few floral buds while too much reduces fecundity – probably through diminished photosynthesis – with an intermediate amount maximising reproduction. The optimal proportion of cephalium becomes smaller as the plant grows, probably because self-shading by new branches causes a further reduction in light interception. Smaller plants had significantly less cephalium than the optimal amount to maximise current reproduction. Since the largest individuals produced more reproductive structures, small cacti may find it more profitable to grow fast to achieve a large fecundity, than to assign resources to immediate reproduction via cephalium development.     

An automatic device to record the force necessary to compensate plant movements

A device, which automatically and continuously keeps moving plants in fixed positions, has been constructed. The apparatus is based on optical detection of any movements of the plant organ under study. The plant organ is kept in the desired position by means of wires, and the force necessary to apply to the wires to achieve this is recorded. The force reflects any tendency of the plant organ to move. The system is controlled by an Apple II computer. The device can work in one or two dimensions and record compensation forces in a wide range. In the experiments mentioned below, the magnitude of the forces necessary to keep the plants in a fixed position was of the order of 10^-4N.
Circadian leaf movements of Oxalis regnellii Mig. were studied in the device. The leaf rhythm continued, although the leaflets were clamped and the light input on the leaf therefore constant. Circumnutation of hypocotyls of Helianthus annus L. cv. Californicus were drastically reduced in amplitude when the hypocotyls were kept in vertical position by the wires. Since the gravitropic input signal to this system was zeroed by the equipment, the results demonstrated that in the absence of gravitropic inputs the circumnutation reactions drastically diminish. This confirmed that circumnutations of these hypocotyls are influenced by gravity. Finally, the apparatus was used to study phototropic reactions: By clamping phototropically stimulated coleoptiles of Avena sativa L. cv. Seger no gravitational stimulations were involved and the phototropic reaction without interference from gravity could be studied.     

A map of rye chromosome 2R using isozyme and morphological markers

Summary The segregation of isozymic loci for leaf peroxidases (L2Per) has been investigated in backcrosses and F₂ offspring of rye lines having purple seeds (Ps) and monstrosum ears (mo). The Ps, L2Per-3b, mo, and L2Per-2 loci were linked. The Ps and mo loci have been previously located on the 2R chromosome, and the L2Per-3b and L2Per-2 loci have been located on the 2RS chromosome arm. The results favor the gene order Ps ... L2Per-3b ... mo ... L2Per-2 or Ps ... mo... L2Per-3b ... L2Per-2. The position of the loci relative to the centromere is still not known, but the obtained results suggest that the mo locus could be located on the 2RS chromosome arm. On the basis of previously reported linkage groups, the most probable arrangement of the loci located on chromosome 2R is: dw2 ... Ps ... (L2Per-3a ... L2Per-3b ... mo) ... L2Per-2. It has not been possible to know the position of L2Per-4 loci (also located on 2RS chromosome arm) relative to L2Per-3a and L2Per-3b loci.     

DDT induced ethological changes in estuarine fish

Synopsis Experiments were carried out to study the feeding rates of the predator fish Therapon jarbua (Forsk) on mullet juveniles, before and after treatment with DDT. Mullet juveniles treated with a subacute concentration, were refused by the control predators, whereas predators treated with a subacute concentration consumed more mullet juveniles. In the present study crescent perch T. jarbua were exposed to subacute and acute concentrations of DDT, and their behaviour was compared with that of the control predators. There were changes in oriented behaviour and co-ordinated movements, and in feeding, aggression and comfort behaviour of the fish. Inflammation in the gills, and caudal fin serration, were noticed in treated fishes. The findings presented here throw light on fundamental pathways by which pollutants interact with the behaviour of fishes.     

A histological and morphometric study on the tissue and cellular distribution of iron in carp Cyprinus carpio L. during chronic waterborne exposure

The effect of long-term (77 day) exposure of carp Cyprinus carpio to low concentrations of waterborne iron (1 mg Fe-dextran l⁻¹) on accumulation and cellular distribution of iron in the liver was assessed using Perl's staining and histological observations and morphometric measurements. Accumulation of iron in the liver occurred after 14 days of exposure, when the majority of the iron was found in the sinusoidal endothelium with lower amounts in the cytoplasm and nuclei of hepatocytes. Upon further treatment the iron was predominantly distributed in the cytoplasm of the hepatocytes either as granules or diffusive iron and in macrophages.