An observation of an association between adaptive pigmentation and thermal tolerance of fish

Replidated experiments indicate an association between thermal tolerance of juvenile bluegill sunfish and adaptive pigmentation to background color. Bluegills exposed to black backgrounds were able to survive higher temperatures longer than those exposed to blond backgrounds, when water temperatures were raised at a rate of 0.1°C/h from 24 to 36°C. Plausible explanations are considered which involve heat radiation effectiveness (by the fish) related to the black body concept, and stress associated with adaptive pigmentation.     

An unusual ultrastructural association of smooth membranes and glycogen particles: The glycogen body

Summary An electron microscope study of the epithelium of rabbit fallopian tube demonstrated a rarely described intracytoplasmic structure consisting of an array of smooth membranes associated with glycogen particles. This organelle is seen exclusively in the ciliated cells. A three-dimensional reconstruction of these glycogen bodies has been made from serial sections. The peripheral localization of the rough-surfaced membranes in continuity with intra-corpuscular smooth membranes, which have lost their granules, suggests a possible role for the rough membranes in the genesis of the smooth membranes of these glycogen bodies. The role of both the smooth and the rough membranes in glycogenesis and glycogenolysis is discussed.This investigation was made in part in the Laboratoire d'Hormonologie et de Cytologie Expérimentale, Hôpital Broca, Paris.     

Temperature-related divergence in experimental populations of Drosophila melanogaster. II. Correlation between fitness and body dimensions

From a laboratory stock of Drosophila melanogaster (Oregon), reared for more than 20 years at 18° C, a new population was derived and maintained at 28° C for 8 years. The chromosomal and cytoplasmic contribution to genetic divergence between the two populations was estimated. Six body traits and reproductive fitness were taken into account. The third chromosome is responsible for the adaptive difference for temperature between the two lines. Temperature-selected genes which control body size are located on the second and third chromosomes, although the contribution of each chromosome depends on the environment in which the flies develop. The correlation between the chromosomal and cytoplasmic contributions to different traits and fitness, changes with temperature. At 28° C the correlation between fitness and each body trait is proportional to the response to selection exhibited by each of them, but this is not true at 18° C. Body size has, therefore, an adaptive significance in relation to temperature, which is expressed only in the environment where selection occurs. Cytoplasmic genes affect almost all characters to an extent similar to that of chromosomal genes. Inter-chromosomal and nucleo-cytoplasmic interactions are present and also change with temperature. In general, genes selected in a given environment produce greater phenotypic changes in that environment than in another. The population that experienced both temperatures is fitter in both environments, suggesting that the capacity to adapt to warm temperatures depends on genes other than those which are involved in the adaptation to cold.     

Ultrastructure of Sporozoites and Zoites of Hammondia heydorni

The ultrastructure of sporozoites and zoites of Hammondia heydorni was studied in cultured bovine cells. In addition to ultrastructural features typical of coccidian parasites, H. heydorni sporozoites and zoites contain rhoptries that are located posteriorly as well as anteriorly. Also, sporozoites contain a posteriorly located crystalloid body (1.2 μm in diameter); a small crystalloid body (0.5 μm in diameter) was occasionally seen in the anterior end. Zoites resulting from the 1st division of endodyogeny contain a posteriorly located crystalloid body, which is absent in zoites formed by subsequent divisions. Zoites contain posteriorly located amylopectin granules and a relatively large anterior vacuole which is not present in sporozoites. During penetration, the host cell plasmalemma ballooned laterally around the sporozoite creating a large cavity, which later disappeared. Sporozoites and zoites undergoing cell penetration usually exhibit partially empty anterior rhoptries; no changes occur in posterior rhoptries. Lysosomes fuse with the par-asitophorous vacuole surrounding killed sporozoites but not live sporozoites.     

Properties,synthesis, and accumulation of storage proteins in Pieris rapae L.

Two kinds of storage proteins (SP-1, SP-2) were confirmed in hemolymph and fat body of Pieris rapae during metamorphosis. Both proteins were present in high concentrations in the hemolymph during the last larval instar. Hemolymph concentrations of SP-1 and SP-2 dropped after pupation as the proteins were being deposited in fat bodies. SP-2 is present in a larger amount than SP-1. Detailed studies on storage proteins determined their properties, mode of synthesis, and accumulation in the fat body. SP-1 has a molecular weight of 500,000 and consists of one type of subunit (M_r 77,000), while SP-2 has a molecular weight of 460,000 and is composed of two types of subunits (M_r 80,000 and 69,000). The pl values of SP-1 and SP-2 were determined to be 6.97 and 7.06, respectively. Fat body cells from 1-day-old fifth instar larvae synthesized storage proteins in large amounts, whereas those from late prepupae exhibited high protein sequestration. Proteins taken up in fat body accumulated in dense granules during the pupal stage but sharply decreased at the adult stage. Morphological changes in the fat body tissues were observed during the larval-pupal transformation; the nuclei of fat body cells became irregularly shaped, and the boundaries between cells seemed to be obscure. Synthesis, storage, or degradation of storage proteins in fat body during development is closely associated with morphological changes in the tissues.     

Ultrastructure of Phasmid Development in Meloidodera floridensis and M. charis (Heteroderinae)

Phylogenetic characters for Heteroderinae Luc. et al., 1988 are evaluated in Meloidodera which is believed to have primarily ancestral characters. Phasmid ultrastructure is observed in second-stage juveniles (J2), third-stage juvenile males, fourth-stage juvenile males, and fifth-stage males of Meloidodera floridensis and M. charis. Phasmid secretion occurs inside the egg before the J1-J2 molt. Before J2 hatch, concentric lamellar membranes occur within the sheath and socket cells. Some membranes become lamellae of the sheath cell plasma membrane; others become multilamellar bodies. During early molting, plasma membrane lamellae disappear and a distal dendrite segment appears in a rudimentary canal. After the molt, the distal dendrite is not present within the canal. The phylogenetic utility of phasmid features is discussed. In both species the ampulla shape and size between molts are stable features in juveniles and males. The posthatch J2 sheath cell receptor cavity may vary in a species specific manner, but comparative morphology requires precise timing after hatch.     

Evidence of a Monoaminergic-Cholinergic Imbalance Related to Visual Hallucinations in Lewy Body Dementia

Senile dementia of Lewy body type is characterized clinically by a relatively acute onset of fluctuating memory loss and confusion, frequently accompanied by visual hallucinations. Neurochemical analyses of temporal cortex has revealed a distinction between hallucinating and nonhallucinating patients in both cholinergic and monaminergic transmitter activities. In contrast with the cholinergic enzyme choline acetyltransferase, which was more extensively reduced in hallucinating individuals, serotonergic S2 receptor binding and both dopamine and serotonin metabolites were significantly decreased in nonhallucinating cases. These results suggest that an imbalance between monaminergic and cholinergic transmitters is involved in hallucinogenesis in the human brain.     

Body shape and differences between species

The variation of body shape among prosimians is reviewed. Special emphasis is placed on the selective advantages, that is the mechanical reasons, to which variants of the locomotor apparatus can be traced back. There are differences found in the cheiridia, but at present they cannot be explained in terms of mechanics; there is nearly no knowledge about the mechanical meaning of their diversity. Myological characteristics of taxa can be explained mechanically, but this has not yet been done. Well known are variations of body proportions. These discriminate higher taxa, and are largely coincident with the often-used locomotor categories. In spite of this, there are only few sound arguments about the real biomechanic value of characteristic proportions for a given locomotor mode. What is known on this field, is reviewed. Progress can be made only, if the mechanical conditions, set by postural behavior and locomotion, are understood completely. The subtle distinctions between lower taxonomic units can normally be identified only on the basis of detailed and quantified analyses of movements on one hand, and of biometrics on the other. In the few cases in which such studies have been made, the differences of morphology fit to the mechanical requirements of locomotion which also differ only in quantitative details.