bluuebunny/crossref_metadata_2025 huggingface dataset:
Formula-feeding reduces lactose digestive capacity in neonatal pigs
Authors: Thymann Thomas , Burrin Douglas G. , Tappenden Kelly A. , Bjornvad Charlotte R. , Jensen Søren K. , Sangild Per T.
Published: May 2006

The intestine of newborn pigs develops rapidly during the first days postpartum. We investigated if feeding milk replacer (infant formula) as an alternative to colostrum has compromising effects on nutrient digestive function in the neonatal period. Nineteen piglets born at termwere assigned to one of four treatments: (1) newborn controls; (2) natural suckling for 24h; (3) tube-fed formula for 24h; (4) tube-fed porcine colostrum for 24h. All three fed groups showed significant increases in small-intestinal and colonic weights, villous heights and widths, maltase and aminopeptidase A activities, and decreases in dipeptidylpeptidase IV activity, relative to newborn pigs. Following oral boluses of mannitol, lactose or galactose, formula-fed pigs showed significantly reduced plasma levels of mannitol and galactose compared with colostrum-fed pigs. Activity of intestinal inducible NO synthase and plasma levels of cortisol were significantly increased, whereas intestinal constitutive NO synthase and α-tocopherol were decreased in formula-fed pigs compared with colostrum-fed pigs. Although formula-fed pigs only showed minor clinical signs of intestinal dysfunction and showed similar intestinal trophic responses just after birth, as those fed colostrum, lactose digestivecapacity was markedly reduced. We conclude that formula-feeding may exert detrimental effects on intestinal function in neonates. Formula-induced subclinical malfunction of the gut in pigsborn at term was associated with altered NO synthase activity and antioxidative capacity.
Sex-related differences in the immune response of weanling piglets exposed to low doses of fumonisin extract
Authors: Marin Daniela E. , Taranu Ionelia , Pascale Florentina , Lionide Alexandru , Burlacu Radu , Bailly Jean-Denis , Oswald Isabelle P.
Published: May 2006

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides, a fungus that commonly contaminates maize. Sex-related effects of FB1 have been observed with respect to carcinogenicity in rodents, to performances in pigs and immunosuppression in mice. In the present study the sex-related effect of FB1 on the pig immune response was determined. Female and castrated male piglets received for 28d either control feed or feed contaminated with 8mg FB1/kgfeed in the form of F. verticillioidesculture material. At day 7 and day 21, animals were immunised subcutaneously with a Mycoplasma agalactiae vaccine. Ingestion of FB1-contaminated feed significantly decreased weight gain in males but had no effect in females. No sex-related difference was observed in biochemical parameters, but a higher level of creatinine was noted in toxin-treated animals. FB1 also altered the pig immune response in a sex-specific manner. In males, ingestion of FB1-contaminated feed significantly decreased specific antibody levels after vaccination as well as the mRNA expression level of IL-10. In females, the toxin has no effect on specific antibodies or on cytokine mRNA levels. The results of the present study indicatethat FB1 is immunosuppressive in pigs. The magnitude of this FB1-induced immunosuppression is highly dependent on sex, with males being more susceptible than females.
trans-10,cis-12 Conjugated linoleic acid inhibits lipoprotein lipase but increases the activity of lipogenic enzymes in adipose tissue from hamsters fed an atherogenic diet
Authors: Zabala Amaia , Churruca Itziar , Fernández-Quintela Alfredo , Rodríguez Víctor M. , Macarulla M. Teresa , Martínez J. Alfredo , Portillo María P.
Published: May 2006

The aim of the present work was to investigate the effects oftrans-10,cis-12conjugated linoleic acid (CLA) on the activity and expression of lipogenic enzymes and lipoprotein lipase (LPL), as well as on the expression of transcriptional factors controlling these enzymes, in adipose tissue from hamsters, and to evaluate the involvement of these changes in the body fat-reducing effect of this CLA isomer. Thirty male hamsters were divided into three groups and fed atherogenic diets supplemented with 0 (linoleic group), 5 or 10gtrans-10,cis-12CLA/kg diet, for 6 weeks. Body and adipose tissue weights, food intake and serum insulin were measured. Total and heparin-releasable LPL and lipogenic enzyme activities (acetyl-CoA carboxylase (ACC); fatty acid synthase (FAS); glucose-6-phosphate dehydrogenase (G6PDH); and malic enzyme (ME)) were assessed. ACC, FAS, LPL, sterolregulatory element-binding proteins (SREBP-1a), SREBP-1c and PPARγ mRNA levels were alsodetermined by real-time PCR. CLA did not modify food intake, body weight and serum insulin level. CLA feeding reduced adipose tissue weight, LPL activity and expression, and increased lipogenic enzyme activities, despite a significant reduction in ACC and FAS mRNA levels. The expression of the three transcriptional factors analysed (SREBP-1a, SREBP-1c and PPARγ) wasalso reduced. These results appear to provide a framework for partially understanding the reduction in body fat induced by CLA. Inhibition of LPL activity seems to be an important mechanism underlying body fat reduction in hamsters. Further research is needed to better characterizethe effects of CLA on lipogenesis and the role of these effects in CLA action.
Phyto-oestrogen intake and plasma concentrations in South Asian and native British women resident in England
Authors: Bhakta Dee , Higgins Craig D. , Sevak Leena , Mangtani Punam , Adlercreutz Herman , McMichael Anthony J. , dos Santos Silva Isabel
Published: May 2006

Phyto-oestrogens, naturally occurring hormone-like chemicals in plant food, may play a protective role against hormone-related chronic diseases. South Asian migrants in the UK have a lower incidence of hormone-related cancer than their hosts but the extent to which this difference may be due to phytoestrogen intake is not known. The aim was to compare habitual phytoestrogen intake in first-generation South Asian migrant women and native British women. South Asian (n 221) and native British women (n 50) were recruited from general practitioner lists and were asked to provide monthly 24h recalls for a period of 1 year. An enhanced phytoestrogen database was compiled using data from a literature search and unpublished data. A sub-sample of South Asian women (n 100) and the native British women (n 40) also provided blood samples every 3 months during the 1-year period. The median daily intakes (μg/d) of isoflavones (184·2 v. 333·9) and lignans (110·8 v. 148·8) were significantly lower in South Asians than in the native British (P<0·001, P=0·04 respectively).There were no significant differences in mean plasma isoflavone levels (nmol/l) but plasma enterolactone was significantly lower in the South Asians (13·9 (sd17·5) v. 28·5 (SD23·3),P<0·001). The main sources of phytoestrogens were bread and vegetables in both ethnic groups. Habitual phytoestrogen intake in South Asian and native British women was below 1mg/d and was higher in the native British diet. The present study does not support the hypothesis that differences in phytoestrogen intake, or in circulating levels, could explain differences in hormone-related cancer risks between these two populations.
Genistein and other soya isoflavones are potent ligands for transthyretin in serum and cerebrospinal fluid
Authors: Radović Branislav , Mentrup Birgit , Köhrle Josef
Published: May 2006

Consumption of soya-based nutrients is increasing in modern society because of their potentially protective effects against chronic diseases. Soya products are also heavily advertised as alternative drugs for relief from symptoms of the menopause and for hormone replacement therapy.However, because of their oestrogenic activity, negative effects of isoflavones have been postulated. Therefore, we analysed influences of soya isoflavones, major soya constituents with endocrine activity, on thyroxine (T4) binding to its distribution proteins. Serum binding of125I-labelled l-T4was analysed in the absence or presence of increasing concentrations of soya isoflavones using non-denaturing PAGE for analysis. Complete displacement of [125I]T4binding to transthyretin (TTR) was observed in human serum incubated with genistein at concentrations >10μm; interference started at >0·1μm. Glycitein showed decreased and daidzein the lowest displacement potency. [125I]T4was displaced to albumin in rat and to T4-binding globulin in human serum. Soya isoflavones also obstruct [125I]T4binding to TTR in human cerebrospinal fluid (CSF). The inhibitory effect was confirmed in direct binding assays using purified TTR with 50% inhibitory concentration values of 0·07μm for genistein, 0·2μm for glycitein and 1·8μm for daidzein. The present study underlined a potent competition of soya isoflavones for T4binding to TTR in serum and CSF. Isoflavones might alter free thyroid hormone concentrations resulting in altered tissue availability and metabolism. As a consequence of this interference, one could expect a disturbance in the feedback regulation of hormonal networks, including the pituitary–thyroid–periphery axis during development and in adult organisms.
A cyanobacterial LPS antagonist prevents endotoxin shock and blocks sustained TLR4 stimulation required for cytokine expression
Authors: Macagno Annalisa , Molteni Monica , Rinaldi Andrea , Bertoni Francesco , Lanzavecchia Antonio , Rossetti Carlo , Sallusto Federica
Published: May 2006

Toll-like receptors (TLRs) function as primary sensors that elicit coordinated innate immune defenses through recognition of microbial products and induction of immune and proinflammatory genes. Here we report the identification and biological characterization of a lipopolysaccharide (LPS)-like molecule extracted from the cyanobacterium Oscillatoria Planktothrix FP1 (cyanobacterial product [CyP]) that is not stimulatory per se but acts as a potent and selective antagonist of bacterial LPS. CyP binds to MD-2 and efficiently competes with LPS for binding to the TLR4–MD-2 receptor complex. The addition of CyP together with LPS completely inhibited both MyD88- and TRIF-dependent pathways and suppressed the whole LPS-induced gene transcription program in human dendritic cells (DCs). CyP protected mice from endotoxin shock in spite of a lower capacity to inhibit LPS stimulation of mouse DCs. Interestingly, the delayed addition of CyP to DCs responding to LPS strongly inhibited signaling and cytokine production by immediate down-regulation of inflammatory cytokine mRNAs while not affecting other aspects of DC maturation, such as expression of major histocompatibility complex molecules, costimulatory molecules, and CCR7. Collectively, these results indicate that CyP is a potent competitive inhibitor of LPS in vitro and in vivo and reveal the requirement of sustained TLR4 stimulation for induction of cytokine genes in human DCs.
Tests of quantum chromo dynamics at
e+e− colliders
Authors: Kluth Stefan
Published: May 2006

The current status of tests of the theory of strong interactions, quantum chromo
dynamics (QCD), with data from hadron production in e+e−
annihilation experiments is reviewed. The LEP experiments ALEPH, DELPHI, L3 and OPAL
have published many analyses with data recorded on the Z0 resonance at
and above up to . There are also results from SLD at
and from reanalysis of data
recorded by the JADE experiment at .
The results of studies of jet and event shape observables, particle production and
quark gluon jet differences are compared with predictions by perturbative QCD
calculations. Determinations of the strong coupling constant from jet and event shape observables, scaling
violation and fragmentation functions (FFs), inclusive observables from Z0
decays, hadronic τ decays and hadron production in low-energy
e+e− annihilation are discussed. Updates of the measurements
are performed where new data or improved calculations have become available. The best
value of is obtained from an average
of measurements using inclusive observables calculated in NNLO QCD: where the error is dominated by theoretical
systematic uncertainties. The other measurements of are in good agreement with this value. Finally,
investigations of the gauge structure of QCD are summarized and the best values for
the colour factors are determined:
with errors dominated by systematic uncertainties and in good agreement with the
expectation from QCD with the SU(3) gauge symmetry.
Reassessing Bittner’s thesis: understanding coercion and the police in light of Waco and the Los Angeles riots
Authors: Vizzard William J.
Published: May 2006

Considers the dilemma of the incompatibility between the role of the police and democratic values, Develops Bittner’s thesis, that Western values continue to move away from legitimate use of force toward coercive intervention, with reference to the Waco siege and the Los Angeles riots.
Rapid cervicovaginal smear screening: method of quality control and assessing individual cytotechnologist performance
Authors: Pajtler M. , Audy‐Jurković S. , Škopljanac‐Mačina L. , Antulov J. , Barišić A. , Miličić‐Juhas V.
Published: May 2006

Aim:  To validate the method of rapid screening (RS) in the detection of cervical lesions and false‐negative results as well as in quality control of cytotechnologist performance.

Material and methods:  The RS method was validated on Papanicolaou‐stained and initially conventionally analysed vaginal, cervical and endocervical (VCE) smears collected in an opportunistic programme for the detection of cervical carcinoma. The study included 3680 VCE smears from the Department of Gynaecologic Cytology, University Department of Gynaecology and Obstetrics, Zagreb University Hospital Center, Zagreb and from the Department of Clinical Cytology, Osijek University Hospital, Osijek. Histologically verified abnormal findings accounted for 10% of the study samples. Thirteen cytotechnologists, with no previous experience in RS, performed the test. Each slide was examined using the ‘step’ technique for 1.5 minutes, the findings were classified as negative or abnormal, and the abnormal ones were also classified according to differential cytological diagnosis. The results were compared with those obtained on initial screening. Abnormal findings from a group of initially negative findings were reanalysed using conventional methods to make definitive cytological diagnosis.

Results:  RS yielded a sensitivity of 83.7%, specificity of 93.7%, positive predictive value of 62.4%, negative predictive value of 97.9% and diagnostic accuracy of 92.6%. Relative to the initial abnormal differential cytological diagnosis, the diagnostic value of RS increased with lesion severity [54.8%, 68.0% and 91.3% for cervical intraepithelial neoplasia (CIN) I, CIN II and CIN III respectively]. RS detected 38 additional positive findings; 94.2% of these were atypical squamous cells of undetermined significance (ASCUS)/abnormal glandular cells undetermined significance (AGUS) and CIN I. The rate of additional positive findings was 1.14% (38/3135). The false‐negative rate of initial screening was 9.4% (38/406), and individual cytotechnologist sensitivity was 60.0–100.0%.

Conclusion:  RS could be introduced as an efficient method of quality control to improve the sensitivity of cytological screening as well as for quality control of cytotechnologist performance.
Morphological correlates of nectar production used by honeybees
Authors: HIGGINSON A. D. , GILBERT F. S. , BARNARD C. J.
Published: May 2006

Abstract 1. Honeybees foraging on lavender have been shown to choose inflorescences that are larger and have more flowers. If they are selecting optimally then these inflorescences should yield higher net rates of energy gain. The number and distribution of flowers within inflorescences is a complex function of age, however, which might itself influence nectar quality and availability.

2. Sampling of the overnight nectar secretion of visited and unvisited inflorescences showed that younger inflorescences with more flowers produced more sugar per flower and had fewer unproductive flowers than other inflorescences, but the size of the inflorescence had no effects.

3. Overall display size attracted bees to inspect inflorescences, as inflorescences that were inspected but rejected were larger and/or had larger or more bracts than those that were ignored. Bees, however, accepted more productive inflorescences based on different cues: inflorescence age and number of flowers.

4. Inflorescence choice thus appeared to reflect a two‐stage decision process based on different morphological criteria at each stage.
Quantitative studies on the phytoplankton of the Rivers Thames and Kennet at Reading
Authors: LACK T. J.
Published: May 2006

The phytoplankton of the River Thames and its tributary the River Kennet was studied weekly from May 1966 to May 1968. Samples were concentrated by sedimen‐tation and counted in a haemocytometer.

Data on discharge, temperature and silica concentration are followed by descriptions of the variations in the number and composition of the phytoplankton. In both rivers there were spring and autumn peaks of the centric diatom. Stephanodiscus hantzschii. Chlorophyceae were most abundant during summer. Two cryptophyceans, Cryptomonas and Rhodomonas were sometimes numerous.

In the Thames, the size of the population was closely correlated with the discharge, highest numbers always occurring during periods of low discharge. In the Kennet, increases in discharge often brought about increases in cell number due to the infiux of benthic forms.

It appeared that nutrients were always present in sufficient quantity and did not limit algal growth.

Comparisons were made with earlier studies on the Thames and differences were noted in the composition of the phytoplankton which were almost certainly due to the process of eutrophication.
The chemical composition and flow of the South Winterbourne in Dorset
Authors: CASEY H. , NEWTON PATRICIA V. R.
Published: May 2006

Weekly observations were made of the South Winterbourne from October 1970 to December 1971. Flow commenced in November 1970 and ceased in July 1971, a maximum flow of 1.51 m3 s−1 being recorded in January 1971.

The chemical composition was not very variable, but nitrate showed a positive correlation with flow.
Studies on Gull Lake, Michigan
Authors: MOSS BRIAN
Published: May 2006

Evidence is presented, from studies on deoxygenation of the hypolimnion and from examination of the diatom frustules in a surface mud core, that Gull Lake is becoming progressively more fertile. This appears to be a recent phenomenon, having begun in the last century. Phosphate is identified, from bioassay experiments, as the key nutrient limiting to algal growth. Probable future changes in the lake are discussed, and the existence of `natural' eutrophication is denied.
Analysis of a meristic trait for hybridization in sunfishes (genus Lepomis)
Authors: MISRA R. K.
Published: May 2006

Necessity of a thorought study of hybridization, following the breakdown of reproductive isolating mechanisms between naturally occurring populations, has been felt by biologists in geneeral and ichthyologists in particular. In this connection a formula for ‘hybrid index’ developed mainly by Hubbs & Kuronuma (1942) and Hubbs, Hubbs & Johnson (1943) has widely been in use, to test the assumption of hybridity and to study the mode of inheritance. Misra, Bateson & Keenleyside (1970) gave statistical methods of analysing hybrid indices estimated for characters of the ‘continuous’ type, and also provided a numerical example. Recently Misra (1971) gave a method of doing similar analysis for hybrid indices estimated for meristic characters, but no example was provided, as data were not available to him. This paper presents a study of hybridization in the sunfishes (genus Lepomis) of Pinehurst Lake, Ontario, Canada, based on the number of scales below the lateral line; the primary purpose of the study is to show the complete computational procedure involved in the application of the method of Misra (1971), so that those users of the method who are mainly interested in the applied aspects of the method, can bypass the mathematics easily.
Another instance of haemoglobin in a flatworm (Phaenocora typhlops Vejdovsky 1880)
Authors: YOUNG JOHNSTONE O. , HARRIS JANE H.
Published: May 2006

(1) The occurrence of haemoglobin in Phaenocora typhlops (Vejdovsky) is reported.

(2) Rhabdocoels were examined spectrophotometrically. The distribution of the pigment was studied by a sodium nitroprusside‐benzidine technique, and the distribution of ferric iron with Perl's technique.

(3) Characteristic bands of oxyhaemoglobin were observed at 540 and 580 nm. The oxyhaemoglobin was reduced to haemoglobin by the addition of sodium dithionite and an absorption band appeared at about 560 nm.

(4) Haematin was found principally around the pharynx, though a little was found in front of the latter and along the length of the gut. Ferric iron was distributed throughout the worm.

(5) The occurrence of haemoglobin in P. typhlops and P. unipunctata is compared. It is suggested that less occurs in the former species. Whether or not this is related to the presence of zoochlorellae is considered. Certainly both species burrow actively in mud where reduced oxygen conditions can occur.
A hydrobiological survey of a small Spanish river grossly polluted by oil refinery and petrochemical wastes
Authors: MEYNELL P. J.
Published: May 2006

In a 2½‐month hydrobiological survey of the Rio Ojailén, a tributary of the Rio Guadalquivir in Spain, four aspects of the pollution from an oil refinery and petrochemical complex were considered: physical, chemical, macrobiological and toxico‐Iogical. Near its source the river receives a combined waste making up 75% of its dry weather flow. The wastes are grossly polluting‐from oil, phenols, ammonia, hydrocarbons and other organic materials as well as suspended solids. Though inhibitory to biological degradation, the wastes are gradually purified and diluted with passage downstream and retention in a man‐made lake. No macroinvertebrate life is found for 43 km downstream of the complex, in spite of incoming pure streams which were sampled for comparison. Diptera followed by Odonata are the first to return. The effect of the lake on purification is considerable. Toxicity tests of river water upon mosquito fish show a similar decline in toxicity. An attempt has been made to predict the recovery of the river once treatment plants have been installed by the autumn of 1973.
Observations on the limnology and primary production of a small man‐made lake in the West African savanna
Authors: THOMAS J. D. , RATCLIFFE P. J.
Published: May 2006

1. The results of limnological studies on a small, 35‐ha, triangular man‐made lake and a small adjacent fish pond in the coastal savanna of Ghana are described.

2. The lake, which has a renewal time of approximately 0.96 years, is subject to large, predictable seasonal changes. Water volume and surface area rapidly reach maximum values in the wet season from April to June despite the low runoff values which average only 1.2% of the precipitation. Minimum values occur in the dry season when up to 76% of the lake area may be exposed. Most of the water is lost by evaporation which may amount to 193 cm annually.

3. The annual cycle in water temperature follows that in solar radiation with peaks towards the end of the dry season in March to April and deep troughs in the wet season from April to June. During the dry season the water column is characterized by greater stability, a higher degree of stratification, and a much higher amplitude of diurnal temperature change (4‐5°C) than in the wet season (1°C). Isothermal conditions tend to be approached nocturnally and even during the day in the wet season.

4. The ionic content of the water is low and dominated by bicarbonate, sodium, silica and iron. During the wet season flood water results in a decline in conductivity from 214 to 30 μmhos/cm2, a decrease in pH and transparency, and an increase in oxidizable organic material. Except for the conductivity these values return to normal in about 6 weeks as a result of rapid decomposition of allochthonous materials.

5. The oxygen pulse is strong and photosynthetic activity by phytoplankton high during the dry season whereas in the wet season the converse is true. As a result of the low concentration of organic carbon (0.10–0.35%) in the sediments their oxygen demands are low. Consequently, dissolved oxygen values near the sediment are relatively high and oxygen stratification poorly‐developed. Most of the organic carbon appears to be recycled in the water column rather than in the sediments as is generally the case in tropical ecosystems.

6. Rooted vegetation became permanently established in the fish pond but not i n the lake itself. Emergent and floating vegetation which grows profusely in the draw‐down area in the wet season is for the most part exported from the system by wind and biological agencies and, therefore, contributes little to the energy and mineral budgets of the lake. Primary production in the water column is mainly by Myxophyceae and Bacillariophyceae and is low during the dry season (1.35 gC/m2/day) and very low in the wet season. Possible reasons for the low level of primary production are discussed.
Emergence patterns of Plecoptera in a stream in Oregon, USA
Authors: KERST CARY D. , ANDERSON N. H.
Published: May 2006

Forty‐three species of Plecoptera were collected from emergence traps in an Oregon woodland stream. Adults occurred during every month of the year, but the largest numbers and most species emerged from April to June. Temporal separation of con‐generic species occurred within the suborder of Filipalpia, but not in Setipalpia. Some species of Nemoura had split emergence periods.

The onset of emergence for a species from year to year generally varied by less than 2 weeks. Peak emergence occurred at least 1‐2 weeks after the start ofthe emergence period.
Seasonal variation of sieving efficiency in a lotic habitat*
Authors: BARBER WILLARD E. , KEVERN N. R.
Published: May 2006

Sieving efficiency, defined as the percent increase in yield of numbers or biomass of organisms, obtained by use of a sieve with 0‐25‐mm mesh openings instead of a 0‐50‐mm meshed sieve, was investigated in a lotic habitat over a 12‐month period. Greatest elficiencies obtained were 300 to 600% for mayflies, chironomids, simuliids, ‘other dipterans,’ water mites and plecopterans and 90 and 190% for trichopterans and coleopterans, respectively. For the fauna as a whole, efficiency varied from 95 to 325% over the study period.

Efficiency in estimating biomass was not as great as that with numbers and generally was below 10% for trichopterans. mayflies, ‘other dipterans’, coleopterans and the fauna taken as a whole. For chironomids, simuliids and water mites efficiencies generally were higher than 10% and reached as high as 174%, 60% and 80%, respectively. In all groups efficiency varies throughout the year with lowest occurring during winter months.

The findings are compared with data found in the literature and discussed in relation to structural, behavioural, and life history characters.
A silica budget for Lough Neagh 1970–1972
Authors: DICKSON E. L.
Published: May 2006

In this study of the Lough Neagh catchment a relationship has been sought between the loads of dissolved and total silica and the flow of each of the six inflowing rivers. Two of these rivers‐the Main and Six Mile Water‐carry a higher ratio of dissolved to total silica than do the remaining four rivers due to the geology of the catchment. The multiple regressions of loads in tonnes against river flows in cubic metres show a linear relationship for dissolved but not for total silica. The explanation for this non‐linearity has been sought in the river proaies, where the fall for the last 30 m varies from 5 to 25 km depending on the river. The rivers Main and Six Mile Water are the steepest, and linear relationships were obtained in their regressions while the shallowest profile was found in the Blackwater where non‐linearity in the multiple regression was obtained.

In Lough Neagh the dissolved silica content was gradually reduced from early winter through to springtime by diatom growth and a balance has been drawn up for this utilization. This reduction also compares with the quantity in the diatom crop at maximum based on cell volume measurements. The summer build up of the dissolved silica content of the lough has been shown to be greater than the quantity contributed by the inflowing rivers from late spring to autumn and the data show that the recycling of silica from some 65% of the frustules from the spring crop after its collapse would account for the summer increase.
Weight of food and time required to satiate brown trout, Salmo trutta L.
Authors: ELLIOTT J. M.
Published: May 2006

Brown trout of different weights (range 8‐358 g) were fed to satiation at fifteen different water temperatures (range 3.8–21.6°C. Both the weight of the trout (Wg) and the water temperature (T°C) affected the maximum weight of food (Q mg) consumed in a meal, and the relationship between the three variables was well described by a multiple regression equation which can be used to estimate the value of Q (with 95% confidence limits) for trout of different weights at different temperatures between 3.8°C and 21.6°C. The satiation time (with 95% confidence limits) can also be estimated from a multiple regression equation for trout of different weights at temperatures between 6.8°C and 18.1°C. Estimates from the multiple regression equations were applicable to a wide range of food organisms with the exception of larvae ofTenebrio molitor (mealworms). Appetite (measured by voluntary food intake) varied with temperature and was greatest between 13.3°C and 18.4°C. From comparisons with the results of other workers, it was concluded that the maximum amount of food consumed in a meal may provide sufficient calories for both the daily metabolic requirements and the daily maintenance requirements of a trout at temperatures between 3.8°C and 18.4°C, but not at temperatures above 18.4°C.
Critical notes on a proposed method to estimate production
Authors: ZWICK PETER
Published: May 2006

To estimate annual production, Hamilton (1969) initially calculated mean losses/sample, as did Hynes (1961) and Hynes & Coleman (1968). While the latter failed to convert these means to annual production, Hamilton has overcome this problem by assuming a population at equilibrium. Then, production may be calculated by multiplying mean losses with the number of classes through which specimens can grow. The method was claimed to be suitable for unidentified material and not to depend strongly on growth patterns; both claims are refuted here. The main objection is that for calculations, populations must be divided into fractions. While equilibrium might be acceptable for an entire population, it is not for any of its fractions. The particular conversion factor therefore has no justification and the method becomes inapplicable.
Food of the New Zealand trichopterans Hydrobiosis parumbripennis McFarlane and Hydropsyche colonica McLachlan
Authors: CROSBY T.K.
Published: May 2006

The food of the larvae of two New Zealand Trichoptera, Hydrobiosis parumbripennis and Hydropsyche colonica, was investigated between March and November 1971 at the Wainui Valley Stream, Canterbury, New Zealand. Most samples were collected from an experimental channel constructed in the stream in 1970. The first three instars of H. parumbripennis were mainly detrital feeders, whereas the two later instars were exclusively carnivorous. In contrast, H. colonica was omnivorous. The main prey taken by H. parumbripennis were larvae of a simuliid, Austrosimulium tillyardianum, Chironomidae (subfamily Orthocladiinae), and an ephemeropteran, Deleatidium sp. The first three instars appeared to select chironomids in preference to simuliids, whereas the converse was true for the final two instars. The main prey taken by H. colonica was A. tillyardianum. The size of prey and the mean number of prey found per larva of H. parumbripennis increased with each instar. Forage ratios indicated that H. parumbripennis were eating A. tillyardianum at the same relative frequency as their abundance in the fauna, but that the chironomids and Deleatidium sp. were being preferentially selected as prey. Cased caddis larvae were avoided as food items, as was the mollusc Potamopyrgus antipodarum. Although H. parumbripennis was the most important predator of A. tillyardianum in the stream, it is considered that it has little effect on the simuliid population.
The distribution and habitat separation of three corixids (Hemiptera: Heteroptera) in western Colorado
Authors: DODSON VIRGINIA E.
Published: May 2006

Three species of Corixidae (Hemiptera : Heteroptera) were studied in thirty montane, sub‐alpine, and alpine ponds in Western Colorado. Callicorixa audeni Hung, had the widest altitudinal range (2800‐3400 m). Cenocorixa bifida Hung, was most common in montane ponds. Arctocorisa lawsoni Hung, was found only above 3100 m. C. audeni was significantly associated with C. bifida and A. lawsoni. Habitat selection was studied in two montane (2900 m) and one alpine (3480 m) pond. C. audeni utilized both mud and emergent sedges as perching and feeding sites, occurring more frequently in the sedges in the montane ponds. C. bifida was confined to the mud. In the alpine pond, A. lawsoni was most abundant on the mud; C. audeni occurred equally on the mud and in the sedges. All three species preferred shallow water (less than 0·5 m). A. lawsoni occupied deeper water more often than C. audeni. In substrate selection experiments C. audeni occupied emergent sedges more than C. bifida, confirming field observations. C. bifida occurred in sedges in the aquaria, but not in the montane ponds, suggesting that an interspecific interaction may be excluding C. bifida from the sedges in nature.
A pneumatic grab for obtaining large, undisturbed mud samples: its construction and some applications for measuring the growth of larvae and emergence of adult Chironomidae
Authors: MURRAY T. D. , CHARLES W. N.
Published: May 2006

A description is given of the construction and operation of a pneumatic grab taking samples of mud 0.25 m2 in area, which can be removed without disturbance. These are of value in a variety of studies, and examples are given of their use for maintaining enclosed benthic populations and for measuring the emergence of adult Chironomidae.
Seasonal changes of Bosmina (Crustacea, Cladocera) in Frains Lake, Michigan: laboratory observations of phenotypic changes induced by inorganic factors
Authors: KERFOOT W. CHARLES
Published: May 2006

In Frains Lake, individuals of the species Bosmina longirostris decrease relative mucro and antennule lengths during the spring and summer, and increase them again during the fall. The cyclomorphosis involves both embryonic and post‐embryonic events, since the relative sizes of parts in neonates and the relative growth rates of parts in later instars change seasonally. Antennules grow during winter, but may even regress during summer. Mucrones show an opposite pattern, growing maximally during late summer and fall.

The kinds of cyclomorphotic changes in Bosmina suggest evolutionary adjustments to two principle types of predators: visual vertebrates and blindly grasping invertebrates. While laboratory experiments implicate temperature and turbulence as proximate factors in the cyclomorphotic changes, some unknown factor (or factors) also appears necessary to stimulate the magnitude of responses observed in nature.
Periphyton production and grazing by chironomids in Alderfen Broad, Norfolk
Authors: MASON C. F. , BRYANT R.J.
Published: May 2006

The standing crops of periphyton were measured on dead Typha stems and glass rods in a small, eutrophic lake from February to November. Chironomid larvae were also counted on the Typha stems; very few were present on the glass rods. The standing crop of periphyton on the Typha stems fell from 1.8 mg cm−2 in early April to nearly zero in November. On the glass rods the periphyton reached a peak of 1.93 mg cm−2 in late May and 1.94 mg cm−2 in July, thereafter falling to a steady level of 1.6 mg cm−2. The population of chironomids showed a peak in late May and then declined. The alimentary canals of chironomids collected fromTyphastems contained diatoms and filamentous algae so it appeared that chironomids were grazing down the periphyton. Chironomids moved on to theTyphastems in spring and returned to the mud in autumn. The periphyton is a richer source of essential amino acids than the mud, so that a movement from mud to reedstems in spring may increase the rates of growth and metamorphosis of the larvae.

A crude production estimate gave a net primary production of periphyton of 170 mg dry wt m−2 day−1; the periphyton, however, would have contained bacteria and many small animals as well as algae.
Downstream drift of invertebrates in a river in southern Ghana
Authors: HYNES J. D.
Published: May 2006

The results of quantitative sampling of the drifting invertebrates from a riffle area in the upper reaches of the Pawmpawm River in the forest of Ghana are presented. The observations were made once a month during 14 months, April 1970 to May 1971, and also on a daily basis for 3 weeks. Changes in numbers and composition of the animals drifting were examined in relation to the volume of water flowing and the current; there appeared to be two distinct drift phenomena, ‘true’ and ‘background’ drift. The animals belonging to each of these two components are discussed in relation to their response to light, to diurnal fluctuations in total drift and to the phases of the moon. There was a peak drift activity after sunset in those animals which are affected by light, e.g. Centroptilum, Austrocaenis, Chironomidae, Simulium. It is concluded that drift may be simply a function of the activity patterns of the insects.
Chemistry and biology of the South Winterbourne, Dorset, England
Authors: CASEY H. , LADLE M.
Published: May 2006

Changes in discharge and chemical composition are related to biological and physical conditions at eight sites on the South Winterbourne from the source to the confluence with the River Frome. The results show a complex pattern of discharge with nitrate peaks at high discharge values. Mean phosphate values varied from 34·2 μg l−1 (at the source) to 164·6 μg l−1.

The Winterbourne has a rich flora of algae and higher plants of which the annual sequence is influenced by the flow regime and the effects of human interference by cutting and removal of plants and addition of nutrients. The fauna has much in common with permanent chalk streams but temporary flow conditions favour insects having prolonged resting stages or those which are able to colonize quickly from other areas when flow commences. Many non‐insect groups particularly snails, are able to withstand relatively long dry periods.
Biomass and energy transfer by a specialized predator of aquatic snails
Authors: ECKBLAD JAMES
Published: May 2006

The predatory larvae of Sepedon fuscipennis (Diptera: Sciomyzidae) feed only on aquatic pulmonate snails. Under laboratory conditions these larvae utilized ingested snail tissue more efficiently when a lower snail biomass was ingested at lower snail densities. The adaptive value of this response to fluctuating prey availability is suggested.
The colonization of squares of plastic suspended in midwater
Authors: MACAN T. T. , KITCHING ANNETTE
Published: May 2006

(1) A flat substratum hung in midwater is colonized rapidly by a number of species normally found in vegetation. Some have been recorded consistently, a greater number occasionally, but only a few have not been recorded at all. Evidently most species are moving round frequently, even those, such as snails and case‐building caddis‐larvae, that cannot swim. (2) It seems likely from this that the identity of the plant cover has less influence on the structure of a community than some have thought. (3) A comparison of flat sheet, pleated sheet and artificial Littorella suspended in midwater makes possible certain statements and deductions. (i) Leptophlebia, Enallagma and chironomid larvae are more numerous on artificial Littorella; their natural habitat is within the vegetation cover. (ii) Cloeon, Cyrnus and Holocentropus are as numerous on the sheets or more numerous than in the artificial vegetation; they inhabit the surface of the plant cover where Cloeon is protected by its speed, and where the polycentropopids, protected by their nets, can trap both the true plankton and the Cladocera which feed in the vegetation. (iii) The foot of a snail and the suckers of a leech are most effective on a flat surface, which also provides a good feeding place for a snail. The higher numbers of Lymnaea and Erpobdella on the pleated compared with the flat sheets indicates the importance of cover for these two animals. (4) Flat plastic sheets hanging in the illuminated zone would improve the production of fish a little, pleating the sheets would improve it a little more, and best results would come from hanging something with a greater resemblance to natural vegetation.
Observations on the superficial sediment temperatures of some lakes in the southeastern United States*
Authors: LEWIS WILLIAM M.
Published: May 2006

Temperatures of the water column and upper 5 cm of sediment were monitored over a yearly cycle in two South Carolina lakes. Occasional supportive data were also obtained for several lakes in north central Florida. Plans are given for a new type of sediment‐interface sampler that is useful in obtaining detailed temperature or chemical profiles extending from the sediment surface upward. The sampler was used in the investigation to demonstrate the thermal microstratigraphy near the mud surface.

The deep‐water (16 m) temperature for the larger of the two South Carolina lakes changes seasonally from 10·5°C in February to 18·0°C in July. The smaller, shallower (11 m) lake follows an almost identical seasonal cycle but is always 4·0°C cooler because the larger lake receives a heated effluent that has a long‐term effect on hypolimnetic temperatures. In both lakes the uppermost sediments are warmer than the overlying water by an average of 0·1 to 1·0°C during the warming period. Heat accretion near the bottom continues but is slower after stratification, probably due to the relatively low temperature (density) differential between water layers in these warm lakes. Cooling in deep water begins long before breakdown of stratification and is apparently caused by cold density currents from the shallows. The coldest water is located in a thin layer just over the sediment. There is evidence from one of the South Carolina lakes and from the Florida lakes that when the density flows begin they at first flow over a warmer water layer that is more dense due to a high electrolyte content derived from the sediment.

There is a slight deep water warming in all of the lakes when stratification breaks down. After destratification, the deep water is cooled by turbulence rather than density flows. The surface sediments at this time are consistently warmer than the hypolimnion and remain so through the cooling period. There is strong evidence from one Florida lake that turbulence mixes the upper 3 cm of sediment during the isothermal period.

It is concluded that the sediment‐water interface of a warm lake will in general experience greater heat flux than that of a comparable cold lake during the periods of temperature maximum and minimum. Conversely, there is likely to be less heat flux during the warming and cooling periods of warm lakes than of cold lakes. Several expected differences in seasonal patterns of temperature and water movement in the deep water of warm and cold lakes are discussed.
Nitrogen nutrition of Myriophyllum spicatum: uptake and translocation of 15N by shoots and roots
Authors: NICHOLS DALE S. , KEENEY DENNIS R.
Published: May 2006

Intact Myriophyllum spicatum plants were grown in compartmentalized containers in a growth room so that the roots were separated from the shoots by a watertight partition. Nitrogen 15N was added to the water or sediment to trace the uptake of inorganic N by the plant shoots or roots. Myriophyllum spicatum is capable of taking up inorganic N through both roots and shoots. Plant N requirements can apparently be met by root uptake alone. However, when about 0·1 mg/l of NH4‐N were present in the water, foliar uptake supplied more N to the plants than did root uptake. Foliar uptake of NH4‐N was found to be several times faster than that of NO3‐N when both forms of N were present in the water. Only about 1% of the N taken up by the roots was subsequently released to the water through the foliage.
The distribution of the freshwater Malacostraca in the area of the Mersey and Weaver River Authority
Authors: HOLLAND D. G.
Published: May 2006

Freshwater Malacostraca distribution data acquired through the routine biological work of a river authority is of general scientific interest. The distribution of Asellus aquaticus and Gammarus pulex is related to pollution and natural factors. Although widespread in the area, both species are absent from an extensive part of the major river system. A. meridianus appears to be less successful in competition with A. aquaticus and is comparatively scarce, being mostly limited to isolated pools. The distribution of Crangonyx pseudogracilis in canals and static waters is also related to pollution and natural factors. Orchestia cavimana, a semi‐terrestrial amphipod, is shown to be an overlooked species which is common in canals.
The inland distribution of brackish‐water Gammarus species in the area of the Mersey and Weaver River Authority
Authors: HOLLAND D. G.
Published: May 2006

(1) Many inland saline waters exist in Cheshire and South Lancashire mostly in association with the Cheshire Salt Field.

(2) The presence of brackish‐water Gammarus species in this area has been known for many years but has never previously been fully documented.

(3) The saline waters are described in detail.

(4) The distribution of three species of Gammarus in all these waters is also described.

(5) Theories are put forward to explain the presentday distribution of the species in relation to the possible points of entry into the area.
A trap for capturing planktonic chironomid larvae
Authors: DAVIES BRYAN R.
Published: May 2006

This paper describes the construction and field operation of a trap designed to investigate the movements of larval Chironomidae in the open water of lakes. Although the trap was designed to be multidirectional, with six trapping bottles, only two directional components, vertical and horizontal, could be distinguished. This led to examination of three bottles only during later field studies, namely bottle 1 facing into the current, bottle 5 facing the substrate and bottle 6 facing the surface of the lake. Some results are presented and trap operation and sampling efficiency discussed.

A major advantage of the trap is its use as a long term accumulator of planktonic organisms as opposed to traditional spot sampling techniques which tend to miss the less numerous plankters.
A battery‐operated, flow‐through thermistor thermometer
Authors: MOORE W. H.
Published: May 2006

A battery‐operated self‐balancing thermistor temperature indicator is described, producing a D.C. voltage output, 1 V or less, to a recorder or moving coil meter.