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.     

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.     

Extreme Seasonal Growth in Arctic Deer: Comparisons and Control Mechanisms

Arctic ungulates have the capacity to voluntarily restrict growthto times of the year of predictable high quality seasonal herbageabundance. The constraints of the arctic environment mean thatnot only must the timing of this growth seasonality be accuratebut growth rate must be maximised for a short period of time.It is known that daylength is a critical cue for the timingof seasonal rhythms of growth; a manipulated photoperiod of16L:8D stimulates out of season growth in reindeer during winterand this growth is associated with an increase in the plasmalevels of insulin like growth factor 1 (IGF 1). In contrasta manipulated photoperiod of 8L: 16D delays the spring risein growth. There is good evidence from a boreal cervid, thered deer, that the number of hours of day influences growthrate also and this is associated with IGF 1. Thus daylengthmay have a dual role in growth seasonality, timing and amplitude.Although the mechanisms underlying the timing of rhythms bydaylength are partly understood a putative role for daylengthin controlling the rate of an event is a new concept.     

Responses of Aquatic Invertebrates to Declining Oxygen Conditions

Several models for the analysis of data relating the rate ofoxygen uptake to environmental oxygen level have been evaluated.We conclude that the quadratic (or second-degree) polynomial,though hardly perfect, is the best. Data from 31 species ofaquatic invertebrates are described by constants of the quadratic(or second-degree) polynomial equation. The results suggesta phylogenetic trend of increasing regulation of aerobic metabolismin response to declining environmental levels as animals acquirestructures that effectively insulate their respiring tissuefrom the habitat. Many of these species apparently cease withdrawingoxygen from their external environment long before they haveexhausted its supply. Presumably, those species with long lastinginternal oxygen reservoirs, such as gas bubbles or pools ofhigh oxygen affinity hemoglobin, continue to operate aerobicpathways, but those without substantial oxygen storage devicesmust switch over to anaerobic pathways, despite the availabilityof small residual volumes of external oxygen.     

Cryptic speciation and phylogeographic relationships in the elephant ear sponge Ianthella basta (Porifera,Ianthellidae) from northern Australia

Morphological delineation of sponge species is hindered by the narrow range of fixed diagnostic characters and our limited knowledge of how much phenotypic plasticity the sponge body plan assumes in response to environmental conditions. Here, we make use of the partial mitochondrial cytochrome c oxidase subunit I (COI) gene and the second internal transcribed spacer (ITS2) region to assess the taxonomic validity of colour morphotypes observed in the elephant ear sponge Ianthella basta (Pallas, 1776) across its distribution range in northern Australia, and explore levels and patterns of genetic diversity among populations of the species collected from both sides of the Torres Strait. Molecular phylogenetic analyses revealed congruent topologies consistent with three evolutionarily significant units (ESUs) that were independent of the morphology of the sponge. ESU I includes previously morphologically and genetically delineated western Pacific specimens of I. basta (Guam), and probably corresponds to the type specimen originally described from Indonesia. ESU I occurs in almost all sampling sites across northern Australia, suggesting considerable levels of connectivity among reefs throughout the Torres Strait. ESUs II and III are each exclusively associated with a geographic region of high sponge species richness separated by Torres Strait, and probably represent the result of historical population fragmentation. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 225–235.     

The effect of bacterially‐dense environments on the development and immune defences of the blowfly Lucilia sericata

Competitive interactions between insects and microbes and the associated cost of development in bacterially‐dense environments are investigated using the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) as a model. The effects of developing in a bacterially‐dense environment are measured by assessing the fitness consequences of competition using the pathogen Staphylococcus aureus. Fitness is quantified in terms of larval survival, puparial development and adult emergence.The influence of bacteria on larval immune defences is investigated using optical density to assess whether antibacterial potency of the larval excretion/secretion changes in response to the degree of contamination of the larval environment. The results obtained demonstrate that bacterial presence has no detrimental effect on survival of L. sericata from egg to adult eclosion, or on puparial size. Additionally, the level of microbial contamination of larvae has no effect on the antibacterial potency of the larval excretion/secretion. These findings confirm that larval antibacterial activity is not induced by the presence of environmental bacteria but is produced constitutively.     

The significance of biological races of Ditylenchus dipsaci and their hybrids

Pure cultures of six races of Ditylenchus dipsaci derived from a single female, namely, lucerne race (LR), red clover race (RCR), white clover race (WCR), narcissus race (NR), tulip race (TR) and oat race (OR) were inoculated into eight plant species growing in pots. Onion was host to all six races, and tulip to all except RCR, whereas lucerne was susceptible only to LR and slightly to WCR. Hyacinth was not very susceptible to any race. The TR and OR were the most polyphagous. Severe symptoms were not necessarily associated with large nematode populations. Parthenogenesis did not occur. Ten fertile hybrids between races were produced and the host range of five of these was tested. On average the hybrids multiplied less than their parent races and their host ranges showed no relationship to those of their parent races. RCR and TR inoculated together into tulip produced significantly fewer nematodes than did TR alone and more than RCR alone. Mixed populations of races occur in nature which are probably a mixture of parental races, their hybrids and back-crosses. Repeated back-crossing of the hybrids with parental types and the slower multiplication of the hybrids is an explanation for the variation in host range of known races and the failure to record new races.     

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.     

SOME INTERRELATIONSHIPS BETWEEN MANGANESE, MOLYBDENUM AND VANADIUM IN THE NUTRITION OF SOYBEAN, FLAX AND OATS

Soybean and flax were grown in nutrient solutions containing high and low levels of molybdenum and vanadium, in combination with toxic (10–25 p.p.m.) and non-toxic (1 p.p.m.) manganese. Molybdenum (20 and to a less extent 10 p.p.m.) intensified the chlorosis induced by manganese excess, though these concentrations were harmless in the presence of 1 p.p.m. Mn. Vanadium (= 1.0, 5 and 10 p.p.m. Mo) counteracted some of the symptoms of manganese toxicity, but the two higher rates were harmful to growth irrespective of the manganese supply. Toxic concentrations of vanadium at first deepened the green colour of the shoot, though apical iron-deficiency chlorosis was generally induced later. Low molybdenum (0.1 p.p.m.) or equivalent vanadium had no influence on growth or iron nutrition at either level of manganese. Visual differences were corroborated by changes in the nitrogen, phosphorus and iron contents of the plants. There was no evidence of replaceability of molybdenum by vanadium.
Oats were grown in nutrient solutions containing various combinations of manganese (nil–400 p.p.m.) and molybdenum (nil–20 p.p.m.). The appearance of manganese-deficiency symptoms was not affected by the quantity of molybdenum provided, and the manganese and molybdenum contents of the leaves were mutually independent of the quantity of each element supplied.