Elevated atmospheric carbon dioxide impairs the performance of root‐feeding vine weevils by modifying root growth and secondary metabolites

Predicting how insect crop pests will respond to global climate change is an important part of increasing crop production for future food security, and will increasingly rely on empirically based evidence. The effects of atmospheric composition, especially elevated carbon dioxide (eCO₂), on insect herbivores have been well studied, but this research has focussed almost exclusively on aboveground insects. However, responses of root‐feeding insects to eCO₂ are unlikely to mirror these trends because of fundamental differences between aboveground and belowground habitats. Moreover, changes in secondary metabolites and defensive responses to insect attack under eCO₂ conditions are largely unexplored for root herbivore interactions. This study investigated how eCO₂ (700 μmol mol^?1) affected a root‐feeding herbivore via changes to plant growth and concentrations of carbon (C), nitrogen (N) and phenolics. This study used the root‐feeding vine weevil, Otiorhynchus sulcatus and the perennial crop, Ribes nigrum. Weevil populations decreased by 33% and body mass decreased by 23% (from 7.2 to 5.4 mg) in eCO₂. Root biomass decreased by 16% in eCO₂, which was strongly correlated with weevil performance. While root N concentrations fell by 8%, there were no significant effects of eCO₂ on root C and N concentrations. Weevils caused a sink in plants, resulting in 8–12% decreases in leaf C concentration following herbivory. There was an interactive effect of CO₂ and root herbivory on root phenolic concentrations, whereby weevils induced an increase at ambient CO₂, suggestive of defensive response, but caused a decrease under eCO₂. Contrary to predictions, there was a positive relationship between root phenolics and weevil performance. We conclude that impaired root‐growth underpinned the negative effects of eCO₂ on vine weevils and speculate that the plant's failure to mount a defensive response at eCO₂ may have intensified these negative effects.     

Antibiotic Resistance among Escherichia coli O-serotypes from the Gut and Carcasses of Commercially Slaughtered Broiler Chickens: a Potential Public Health Hazard

Presumptive coliform counts and the distribution of Escherichia coli O-serotypes were investigated in chicken rectal contents (175) abdominal cavities (152) and on the carcasses of 44 which had been commercially raised, slaughtered and prepared for sale. Large numbers of E. coli resistant to at least one antibacterial agent were found at each site; comparison of the O-serotypes suggested heavy contamination of the carcass with strains from the gut. The range of O-serotypes was similar to that found in man and some public health implications of cross-infection particularly by handling uncooked birds in the kitchen, are discussed.     

COMPARATIVE ASPECTS OF THE ONTOGENY OF TASTE

Pigs are proposed as a useful laboratory model for the investigationof taste preferences and other controls of ingestive behaviorin the newborn. Suckling pigs can be easily trained to feedthemselves from an artificial feeding apparatus so that intakecan be measured directly. In this manner preferences for glucose,sucrose, fructose and lactose were found in pigs 3 wk of age.The preference threshold for glucose is considerably higherthan that reported for more mature pigs. Taste aversion wasdemonstrated in suckling pigs 2 wk of age. After the taste ofglucose had been paired with LiCl injection, poisoned pigs didnot show the strong glucose preference shown by control pigs.In addition to oropharyngeal controls of intake, gastrointestinalcontrols of intake in the newborn pig were investigated.Loadsof milk or 5% glucose, but not 0.9% NaCl, given by gavage depressedsubsequent intake in piglets 1 wk of age. Caloric or glucostaticmechanisms, but not volume alone, appear to be involved in satietyin the newborn pig. ^*Supported by USPHS Special Fellowship 5F03 AM55321-02 to K.A.H.Request for reprints should be sent to Dr. K. A. Houpt, Dept.of Physiology, N.Y.S. College of Veterinary Medicine, Ithaca,New York 14853, U.S.A.     

Changing viewpoints in neurology as illustrated by certain aspects of cerebrovascular disease

The touchstone of success in the progress of clinical neurology during the latter half of the last century was the careful correlation of clinical observations with the known anatomic facts and, later, the pathologic and physiologic knowledge of the central nervous system. During the past twenty-five years the limitations of this classical approach have become apparent, as has the need for newer methods and the adoption of a dynamic and functional concept to complement the static and structural one hitherto so successful. In respect to cerebrovascular disease, there are significant facts not readily explained in the relatively simple terms of morbid anatomy, such as the finding that in many cases of recent brain infarction no evidence of occlusion of an appropriate artery could be demonstrated, while on the other hand complete occlusion of a cerebral artery can occur without any resultant softening in the area of distribution. The increase in knowledge of the cerebral circulation derived from angiographic studies, and the progress in recognition of the very variable clinical syndromes produced by occlusions of the internal carotid and basilar arteries underline this change from a static to a dynamic concept of disease, a change which has been responsible for the exploitation of the technical advances in the fields of cerebral surgery, neuroradiology and neurophysiology. Inevitably such an approach will likewise insure the success of neurochemical and related techniques which, more and more, are being used in neurological investigation and on which the future growth of neurology increasingly depends.     

Carbohydrate Utilization by the Soil Amoeba Hartmannella castellanii

SYNOPSIS. Carbohydrate utilization by 9 strains of Hartmannella castellanii has been studied by growing the amoebae in a chemically defined medium which did not support growth without an added energy source. Strains differed in the utilization of sucrose, raffinose, melibiose and mannitol. The strains which did not use sucrose for growth were shown to metabolize this sugar: ¹⁴CO₂ was produced and ¹⁴C incorporated into TCA isoluble compounds when the amoebae were grown in the presence of radioactive sucrose.     

THE INFLUENCE OF THE pH OF THE NUTRIENT SOLUTION AND THE FORM OF IRON SUPPLY ON THE COUNTERACTION OF IRON DEFICIENCY IN PEAS, SOYBEAN AND FLAX BY HIGH CONCENTRATIONS OF MOLYBDENUM

The prevention of chlorosis in flax by high concentrations of molybdenum in a nutrient solution was associated with a delay in the precipitation of iron from ferric citrate, a slower drift of pH towards alkalinity and an increase in the iron content of the root. These effects were greater with ammonium than with sodium molybdate and occurred with solutions started at pH 4.6 but not at pH 6.6.
When FeEDTA was the source of iron, a similar delay in pH drift in the solution and accumulation of iron in the root occurred, but there was no chlorosis or precipitation of iron in the control treatment, so the effect of high molybdenum could not be fully determined.
When ferric chloride was used, high molybdenum did not prevent chlorosis nor delay iron precipitation or cause accumulation of iron in the root, though the rate of pH drift resembled that of solutions containing the organic forms of iron.
Similar results were obtained with peas and soybeans receiving high molybdenum treatment, but suppression of chlorosis was only temporary.
It is suggested that the capacity of molybdenum to offset chlorosis is due to the formation, in acid solution, of a complex with phosphorus which renders iron more available by delaying the formation of ferric phosphate. This seems to occur only when iron is supplied in the organic form.     

Spermiogenesis in the Marine Shrimp, Sicyonia ingentis

Spermiogenesis in the marine prawn Sicyonia ingentis was examined using transmission electron microscopy. The acrosomal vesicle, derived from the fusion of pro-acrosomal vesicles blebbed from the nuclear envelope, contains the membrane pouches, anterior granule and a spike. The anterior granule is formed from the coalescence of granular aggregates within the proacrosomal vesicles. Primordia underlying the apical acrosomal vesicle membrane polymerize to form a spike approximately 6 μm long. The convoluted pouch membranes arise from the posterior acrosomal vesicle membrane. Lateral and apical portions of the acrosomal vesicle are surrounded by a pentalaminar membrane comprised of the spermatid plasma membrane and the acrosomal vesicle membrane. Subacrosomal structures include the dense saucer plate, granular core and crystalline lattice. These components condense just posterior to the acrosomal vesicle and are separated from the chromatin by a nuclear plate.
The spermatid nucleus becomes surrounded by rough endoplasmic reticulum (RER) and membranous lamellar bodies. RER gives rise to smooth endoplasmic reticulum. These membrane systems degenerate, forming a band of reticular elements around the lateral and posterior portions of the nucleus. The nucleus undergoes condensation followed by decondensation with concomitant breakdown of the nuclear envelope. The resultant chromatin is fibrillar in appearance.