BOOKS REVIEWS

Book reviewed in this article:
Archeology: Computer Analysis of Chronological Seriation . FRANK HOLE and MARY SHAW
Archeology: Archéologie et calculateurs: problèmes sémi-ologiques et mathématiques . CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE     

Malaria-induced reduction of fecundity during the first gonotrophic cycle of Anopheles Stephensi mosquitoes

Abstract. Anopheles stephensi mosquitoes which had fed upon mice infected with Plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. Fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. Egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of P.y. nigeriensis in the blood affected this relationship. Reduced fecundity was associated with a significant reduction of bloodmeal size (measured by haematin excretion) in mosquitoes which ingested gametocytaemic blood. The bloodmeal size in mosquitoes fed on parasitaemic blood without gametocytes was not significantly reduced. The use of haematin assays for determination of bloodmeal size in mosquitoes is discussed.     

Feeding ecology of the earliest vertebrates

Based on protochordates and extant fish, the earliest Palaeozoic vertebrates were microphagous suspension-feeding animals that pumped food-carrying water very slowly and thus required highly concentrated suspensions. Such conditions exist in benthic (not open water) aquatic environments. Feeding modes which on the basis of extant fish are closely related to benthic microphagous suspension feeding include deposit feeding, epilithic algal scraping, and macrophagous suspension feeding; early jawless vertebrates are predicted to have included all these feeding types. The gnathostome condition is predicted to have followed an initial switch from feeding on suspensions to taking tiny individual food particles (microphagous suspension-feeding → microphagous particulate-feeding → macrophagous particulate-feeding).     

Cryopreservation of the anaerobic rumen fungus Neocallimastix patriciarum

A rapid extraction and purification procedure is described for the preparation of toxic peptides from freshwater blooms and laboratory isolates of Microcystis aeruginosa . Extraction with methanol/butanol, followed by C₁₈ cartridge concentration; gel filtration and high performance liquid chromatography yields discrete toxin peaks. Elution profiles for the laboratory isolates and bloom extracts are compared and the applicability of the method for detecting cyanobacterial toxins in natural waters is discussed.     

TOPICAL APPLICATION OF MOBILE LIQUIDS TO INSECTS BY MEANS OF MICRO-CAPILLARY TUBES

A method is described for topical application of mobile liquids, whether volatile or not, to insects. The principle is that of the self-filling micro-pipette, the 'pipettes' being calibrated lengths of fine, thin-walled glass capillary tube; for use a micro-capillary tube is mounted in a special holder. The doses delivered were shown to be adequately reproducible for mean doses of 0.03 μl. upwards. Precautions in use are: (1) in filling the capillary, its tip is dipped into the reservoir of liquid no more deeply than is necessary: (2) the dose is applied to the insect in such a way that the liquid is carried rapidly away from the delivery tip; and (3) pressure for expulsion of the dose from the capillary is maintained until after the delivery tip is removed from the insect.
A convenient apparatus for keeping a batch of insects under anaesthesia during their dosage is described.     

Input-output relation in a flexor reflex

Observations have been made upon a typical flexor reflex with the aim of disclosing the changes in amount, latency, and temporal configuration of reflex discharge that take place as afferent input is varied from zero to maximal for the band of cutaneous myelinated afferent fibers that extends upward from approximately 6 µ in diameter (group II fibers). Reflex threshold is reached at 6 to 12 per cent maximal afferent input. From threshold to maximal input the relation between input and amount of output is essentially linear, latency on the average decreases, the shorter central paths in general gain preference, but the known minimum pathway, one of three neurons, does not transmit unless aided by convergent activity. Flexor reflex discharge may occur in several bursts suggesting the existence of closed chain connections in the internuncial pools of the spinal cord. At any given input there is, in successively elicited reflexes, little correlation between latency and amount of discharge, at first sight a surprising result for each variable can be taken as a measure of excitability status of the motoneuron population. However, latency of discharge indicates excitability at the beginning of the reflex event whereas amount of discharge is an expression of excitability over the entire period of discharge. Given a constantly and rapidly fluctuating excitability absence of correlation between these variables would be an anticipated result.     

Malic Acid Accumulation in Roots in Response to Flooding: Evidence Contrary to its Role as an Alternative to Ethanol

Across a time course of flooding the malic acid content in rootsof the swamp tree Nyssa sylvatica var. biflora increased 5-foldfrom 1 week to 1 month of flooding and remained at that levelthrough a full year of flooding. Alcoholic fermentation ratesaccelerated within the first month of flooding but dropped tovery low levels under long-term flooding. The theory that, underflooding, malic acid accumulates as an alternative anaerobicend product to ethanol is unlikely in this instance since (1)malate is initially associated with high alcoholic fermentationand (2) the reduction in alcoholic fermentation is accountedfor by increased internal aeration of the roots.