Variants of uncertain significance in prenatal microarrays: a retrospective cohort study.

OBJECTIVE: To categorise the variants of uncertain significance found with prenatal chromosomal microarray and determine the proportion of such variants that are associated with a well-known phenotype in order to establish how often they remain truly of uncertain significance. DESIGN: Retrospective cohort study. SETTING: The University of California, San Francisco. POPULATION: All patients with a variant of uncertain significance on prenatal microarray between 2014 and 2018. METHODS: Each variant was classified as a copy number variant that (a) contains Online Mendelian Inheritance in Man (OMIM)-annotated disease-causing genes ('OMIM morbid genes'); (b) confers autosomal recessive carrier status; (c) is associated with incomplete penetrance; (d) is >1 Mb in size without OMIM morbid genes; (e) demonstrates mosaicism; or (f) contains significant regions of homozygosity. For each variant of uncertain significance, we examined the existing literature to determine whether the predicted phenotype(s) was known. MAIN OUTCOME MEASURE: Prevalence and classification of variants and how much information is available regarding the likelihood of an affected phenotype. RESULTS: Of 970 prenatal microarrays, 55 (5.8%) had at least one variant of uncertain significance. The most common were copy number variants containing OMIM morbid genes (36.8%). In all, 48 (84.2%) were associated with a known phenotype; 55 (96.5%) had data available regarding the likelihood of an affected phenotype. CONCLUSIONS: The prevalence of variants of uncertain significance with prenatal microarray was 5.8%. In the large majority of cases, data were available regarding the predicted phenotype. TWEETABLE ABSTRACT: Variants of uncertain significance occur in 5.8% of prenatal microarrays. In the overwhelming majority of cases, outcome information is available.

Fetal hydrops and the Incremental yield of Next-generation sequencing over standard prenatal Diagnostic testing (FIND) study: prospective cohort study and meta-analysis.

OBJECTIVE: To determine the incremental yield of exome sequencing (ES) over chromosomal microarray analysis (CMA) or karyotyping in prenatally diagnosed non-immune hydrops fetalis (NIHF). METHODS: A prospective cohort study (comprising an extended group of the Prenatal Assessment of Genomes and Exomes (PAGE) study) was performed which included 28 cases of prenatally diagnosed NIHF undergoing trio ES following negative CMA or karyotyping. These cases were combined with data from a systematic review of the literature. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched electronically (January 2000 to October 2020) for studies reporting on the incremental yield of ES over CMA or karyotyping in fetuses with prenatally detected NIHF. Inclusion criteria for the systematic review were: (i) at least two cases of NIHF undergoing sequencing; (ii) testing initiated based on prenatal ultrasound-based phenotype; and (iii) negative CMA or karyotyping result. The incremental diagnostic yield of ES was assessed in: (i) all cases of NIHF; (ii) isolated NIHF; (iii) NIHF associated with an additional fetal structural anomaly; and (iv) NIHF according to severity (i.e. two vs three or more cavities affected). RESULTS: In the extended PAGE study cohort, the additional diagnostic yield of ES over CMA or karyotyping was 25.0% (7/28) in all NIHF cases, 21.4% (3/14) in those with isolated NIHF and 28.6% (4/14) in those with non-isolated NIHF. In the meta-analysis, the pooled incremental yield based on 21 studies (306 cases) was 29% (95% CI, 24-34%; P < 0.00001; I2 = 0%) in all NIHF, 21% (95% CI, 13-30%; P < 0.00001; I2 = 0%) in isolated NIHF and 39% (95% CI, 30-49%; P < 0.00001; I2 = 1%) in NIHF associated with an additional fetal structural anomaly. In the latter group, congenital limb contractures were the most prevalent additional structural anomaly associated with a causative pathogenic variant, occurring in 17.3% (19/110) of cases. The incremental yield did not differ significantly according to hydrops severity. The most common genetic disorders identified were RASopathies, occurring in 30.3% (27/89) of cases with a causative pathogenic variant, most frequently due to a PTPN11 variant (44.4%; 12/27). The predominant inheritance pattern in causative pathogenic variants was autosomal dominant in monoallelic disease genes (57.3%; 51/89), with most being de novo (86.3%; 44/51). CONCLUSIONS: Use of prenatal next-generation sequencing in both isolated and non-isolated NIHF should be considered in the development of clinical pathways. Given the wide range of potential syndromic diagnoses and heterogeneity in the prenatal phenotype of NIHF, exome or whole-genome sequencing may prove to be a more appropriate testing approach than a targeted gene panel testing strategy. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Anthropogenic control over wintertime oxidation of atmospheric pollutants.

During winter in the mid-latitudes, photochemical oxidation is significantly slower than in summer and the main radical oxidants driving formation of secondary pollutants, such as fine particulate matter and ozone, remain uncertain, owing to a lack of observations in this season. Using airborne observations, we quantify the contribution of various oxidants on a regional basis during winter, enabling improved chemical descriptions of wintertime air pollution transformations. We show that 25-60% of NOx is converted to N2O5 via multiphase reactions between gas-phase nitrogen oxide reservoirs and aerosol particles, with ~93% reacting in the marine boundary layer to form >2.5 ppbv ClNO2. This results in >70% of the oxidizing capacity of polluted air during winter being controlled, not by typical photochemical reactions, but from these multiphase reactions and emissions of volatile organic compounds, such as HCHO, highlighting the control local anthropogenic emissions have on the oxidizing capacity of the polluted wintertime atmosphere.

Assessment of alendronate and dietary treatment in the management of feline idiopathic ionised hypercalcaemia and ionised hypercalcaemia associated with chronic kidney disease: 29 cases (2016-2022).

OBJECTIVES: This retrospective cohort multicentre study aimed to characterise the signalment, clinicopathologic data, complications and the association between treatment and outcome (the reduction in ionised calcium concentration) in cats with idiopathic or chronic kidney disease-associated ionised hypercalcaemia managed with alendronate and standard treatment or standard treatment alone, and to compare the outcome between the two groups. MATERIALS AND METHODS: Medical records for cats diagnosed with idiopathic or chronic kidney disease-associated ionised hypercalcaemia were retrospectively reviewed. Cats treated with alendronate and standard treatment were assigned to the alendronate group and cats treated with standard treatment alone were assigned to the control group. The standard treatment was defined as dietary modification and/or monitoring of ionised calcium concentrations and management of complications secondary to hypercalcaemia. The follow-up period was selected as 6 months. RESULTS: Twenty-nine cats were enrolled in the study. Nine cats were included in the control group and 20 cats in the alendronate group. A significant reduction in serum ionised calcium was observed in both groups between the baseline and the follow-up visit; however, this reduction did not differ significantly between both groups (the mean change in the ionised calcium concentration in alendronate and control group was -0.18 and -0.17, respectively). Suspected bisphosphate-related osteonecrosis of the jaw was reported in one cat receiving alendronate. CLINICAL SIGNIFICANCE: In this study, similar reduction in serum ionised calcium concentration was observed in cats with ionised hypercalcaemia treated with diet alone and in cats treated with diet and alendronate. These results should be interpreted with caution, as the study was underpowered for meaningful statistical comparison. Cats receiving alendronate should be monitored for the development of adverse reactions, including osteonecrosis of the jaw.

Diagnostic findings in sinonasal aspergillosis in dogs in the United Kingdom: 475 cases (2011-2021).

OBJECTIVES: To describe the diagnostic tests used and their comparative performance in dogs diagnosed with sinonasal aspergillosis in the United Kingdom. A secondary objective was to describe the signalment, clinical findings and common clinicopathologic abnormalities in sinonasal aspergillosis. MATERIALS AND METHODS: A multi-centre retrospective survey was performed involving 23 referral centres in the United Kingdom to identify dogs diagnosed with sinonasal aspergillosis from January 2011 to December 2021. Dogs were included if fungal plaques were seen during rhinoscopy or if ancillary testing (via histopathology, culture, cytology, serology or PCR) was positive and other differential diagnoses were excluded. RESULTS: A total of 662 cases were entered into the database across the 23 referral centres. Four hundred and seventy-five cases met the study inclusion criteria. Of these, 419 dogs had fungal plaques and compatible clinical signs. Fungal plaques were not seen in 56 dogs with turbinate destruction that had compatible clinical signs and a positive ancillary test result. Ancillary diagnostics were performed in 312 of 419 (74%) dogs with observed fungal plaques permitting calculation of sensitivity of cytology as 67%, fungal culture 59%, histopathology 47% and PCR 71%. CLINICAL SIGNIFICANCE: The sensitivities of ancillary diagnostics in this study were lower than previously reported challenging the clinical utility of such tests in sinonasal aspergillosis. Treatment and management decisions should be based on a combination of diagnostics including imaging findings, visual inspection, and ancillary testing, rather than ancillary tests alone.

Pollen season and climate: is the timing of birch pollen release in the UK approaching its limit?

In light of heightened interest in the response of pollen phenology to temperature, we investigated recent changes to the onset of Betula (birch) pollen seasons in central and southern England, including a test of predicted advancement of the Betula pollen season for London. We calculated onset of birch pollen seasons using daily airborne pollen data obtained at London, Plymouth and Worcester, determined trends in the start of the pollen season and compared timing of the birch pollen season with observed temperature patterns for the period 1995-2010. We found no overall change in the onset of birch pollen in the study period although there was evidence that the response to temperature was nonlinear and that a lower asymptotic start of the pollen season may exist. The start of the birch pollen season was strongly correlated with March mean temperature. These results reinforce previous findings showing that the timing of the birch pollen season in the UK is particularly sensitive to spring temperatures. The climate relationship shown here persists over both longer decadal-scale trends and shorter, seasonal trends as well as during periods of 'sign-switching' when cooler spring temperatures result in later start dates. These attributes, combined with the wide geographical coverage of airborne pollen monitoring sites, some with records extending back several decades, provide a powerful tool for the detection of climate change impacts, although local site factors and the requirement for winter chilling may be confounding factors.

A survey on Shar Pei autoinflammatory disease in the United Kingdom.

OBJECTIVES: To characterise the fever episodes attributed to Shar Pei autoinflammatory disease and to identify common diagnostic and management strategies in the United Kingdom. A secondary objective was to determine risk factors associated with Shar Pei autoinflammatory disease fever episodes. METHODS: A retrospective survey was performed to characterise episodes of Shar Pei autoinflammatory disease fever and to identify commonly used treatments in affected dogs. Clinical data were collected from owners and veterinarians. Frequencies of previously proposed risk factors (skin thickness and folding, muzzle conformation) and comorbid conditions were compared between dogs that had exhibited fever episodes consistent with Shar Pei autoinflammatory disease and those who had not. RESULTS: At least one episode of fever attributed to Shar Pei autoinflammatory disease was reported in 52 of 106 (49%) Shar Pei. Nine other dogs had fever episodes consistent with Shar Pei autoinflammatory disease reported by their owners but not by veterinarians. Median rectal temperature at presentation for Shar Pei autoinflammatory disease fever was 40.1°C [104.2°F] (39.9 to 41.3°C [103.8 to 106.3°F]) and owners reported associated hyporexia (n=33, 63%) and vomiting (n=8, 15%) more frequently than veterinary records (n=22, 42% and n=0, 0%, respectively). The median number of veterinary appointments for Shar Pei autoinflammatory disease was two per dog (1 to 15) while owners reported a median of four episodes per dog per year. None of the assessed phenotypic variants or comorbidities were significantly associated with exhibiting Shar Pei autoinflammatory disease fever episodes. CLINICAL SIGNIFICANCE: Episodes of Shar Pei autoinflammatory disease fever were reported approximately twice as frequently by owners compared to veterinary records, suggesting the burden of this condition may be underestimated by veterinarians. Specific risk factors for Shar Pei autoinflammatory disease fever were not identified.

Impending macrosomia: will induction of labour modify the risk of caesarean delivery?

OBJECTIVE: To compare the annual incidence rates of caesarean delivery between induction of labour and expectant management in the setting of macrosomia. DESIGN: This is a retrospective cohort study. SETTING: Deliveries in the USA in 2003. POPULATION: Singleton births of macrosomic neonates to low-risk nulliparous women at 39 weeks of gestation and beyond. METHODS: Women who had induction of labour at 39 weeks of gestation with a neonatal birthweight of 4000 ± 125 g (3875-4125 g) were compared with women who delivered (either induced or spontaneous labour) at 40, 41 or 42 weeks (i.e. expectant management), assuming an intrauterine fetal weight gain of 200 g per additional week of gestation. Similar comparisons were made at 40 and 41 weeks of gestation. Chi-square test and multivariable logistic regression analysis were used for statistical comparison. MAIN OUTCOME MEASURES: Method of delivery, 5-minute Apgar scores, neonatal injury. RESULTS: There were 132,112 women meeting the study criteria. In women whose labours were induced at 39 weeks and who delivered a neonate with a birthweight of 4000 ± 125 g, the frequency of caesarean was lower compared with women who delivered at a later gestational age (35.2% versus 40.9%; adjusted OR 1.25, 95% CI 1.17-1.33). This trend was maintained at both 40 weeks (36.1% versus 42.6%; adjusted OR 1.31, 95% CI 1.23-1.40) and 41 weeks (38.9% versus 41.8%; adjusted OR 1.16, 95% CI 1.06-1.28) of gestation. CONCLUSIONS: In the setting of known birthweight, it appears that induction of labour may reduce the risk of caesarean delivery. Future research should concentrate on clinical and radiological methods to better estimate birthweight to facilitate improved clinical care. These findings deserve examination in a large, prospective, randomised trial.

The phenology of Rubus fruticosus in Ireland: herbarium specimens provide evidence for the response of phenophases to temperature, with implications for climate warming.

To date, phenological research has provided evidence that climate warming is impacting both animals and plants, evidenced by the altered timing of phenophases. Much of the evidence supporting these findings has been provided by analysis of historic records and present-day fieldwork; herbaria have been identified recently as an alternative source of phenological data. Here, we used Rubus specimens to evaluate herbaria as potential sources of phenological data for use in climate change research and to develop the methodology for using herbaria specimens in phenological studies. Data relevant to phenology (collection date) were recorded from the information cards of over 600 herbarium specimens at Ireland's National Herbarium in Dublin. Each specimen was assigned a score (0-5) corresponding to its phenophase. Temperature data for the study period (1852 - 2007) were obtained from the University of East Anglia's Climate Research Unit (CRU); relationships between temperature and the dates of first flower, full flower, first fruit and full fruit were assessed using weighted linear regression. Of the five species of Rubus examined in this study, specimens of only one (R. fruticosus) were sufficiently abundant to yield statistically significant relationships with temperature. The results revealed a trend towards earlier dates of first flower, full flower and first fruit phenophases with increasing temperature. Through its multi-phenophase approach, this research serves to extend the most recent work-which validated the use of herbaria through use of a single phenophase-to confirm herbarium-based research as a robust methodology for use in future phenological studies.

Diagnosis and morbidity of placenta accreta.

OBJECTIVE: To examine the diagnostic precision of ultrasound examination for placenta accreta in women with placenta previa and to compare the morbidity associated with accreta to that of previa alone. METHODS: This was a retrospective cohort study of all women with previa with/without accreta examined at the University of California, San Francisco (UCSF) between 2002 and 2008. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) of ultrasound examination for the diagnosis of accreta were calculated and compared with results from similar studies in the literature. Univariable analysis was used to compare clinical outcomes. RESULTS: The PPV of an ultrasound diagnosis of accreta was 68% and NPV was 98%. Ultrasound had a sensitivity of 89.5%. Compared with previa alone, accreta had an odds ratio (OR) of 89.6 (95% CI, 19.44-412.95) for estimated blood loss > 2 L, an OR of 29.6 (95% CI, 8.20-107.00) for transfusion and an OR of 8.52 (95% CI, 2.58-28.11) for length of hospital stay > 4 days. CONCLUSION: Placenta accreta is associated with greater morbidity than is placenta previa alone. Ultrasound examination is a good diagnostic test for accreta in women with placenta previa. This is consistent with most other studies in the literature.

Maternal arrhythmia and perinatal outcomes.

OBJECTIVE: The objective of this study was to determine whether arrhythmia in the setting of maternal cardiac disease (MCD) affects perinatal outcomes. STUDY DESIGN: This is a retrospective cohort study of pregnant women with MCD who delivered during 2008 to 2013. Perinatal outcomes among women with an arrhythmia were compared with those without. RESULTS: Among 143 women, 36 (25%) had an arrhythmia. Those with an arrhythmia were more likely to have a spontaneous vaginal delivery (64 vs 43%, P<0.05) and required fewer operative vaginal births (8 vs 27%, P=0.02). Pregnancies were more likely to be complicated by intrauterine growth restriction (IUGR) (17 vs 5%, P<0.05), although there were no differences in the rate of small for gestational age. The risk of IUGR remained increased after controlling for confounding (adjusted odds ratio 6.98, 95% confidence interval 1.59 to 30.79, P=0.01). Two cases of placental abruption were identified among mothers with arrhythmia while none were identified in the controls (P<0.05). CONCLUSION: Patients with arrhythmias were more likely to have a spontaneous vaginal delivery. Our data suggest that these pregnancies were an increased risk for IUGR.

Effects of temperature and drought manipulations on seedlings of Scots pine provenances.

Rising temperatures and more frequent and severe climatic extremes as a consequence of climate change are expected to affect growth and distribution of tree species that are adapted to current local conditions. Species distribution models predict a considerable loss of habitats for Pinus sylvestris. These models do not consider possible intraspecific differences in response to drought and warming that could buffer those impacts. We tested 10 European provenances of P. sylvestris, from the southwestern to the central European part of the species distribution, for their response to warming and to drought using a factorial design. In this common-garden experiment the air surrounding plants was heated directly to prevent excessive soil heating, and drought manipulation, using a rain-out shelter, permitted almost natural radiation, including high light stress. Plant responses were assessed as changes in phenology, growth increment and biomass allocation. Seedlings of P. sylvestris revealed a plastic response to drought by increased taproot length and root-shoot ratios. Strongest phenotypic plasticity of root growth was found for southwestern provenances, indicating a specific drought adaptation at the cost of overall low growth of aboveground structures even under non-drought conditions. Warming had a minor effect on growth but advanced phenological development and had a contrasting effect on bud biomass and diameter increment, depending on water availability. The intraspecific variation of P. sylvestris provenances could buffer climate change impacts, although additional factors such as the adaptation to other climatic extremes have to be considered before assisted migration could become a management option.

Effects of elevated CO2 and temperature on growth and allometry of five native fast-growing annual species.

Whereas much is known of the short-term growth response to elevated atmospheric CO2 concentrations, [CO2 ]elev , there is relatively little information on how the response of native species is modified by temperature, despite the fact that an increase in global mean temperature is expected to accompany the rise in [CO2 ]. In this study, five functionally related annual native species were exposed to different combinations of ambient and elevated [CO2 ] and temperatures in order to assess their response in terms of growth and allometry. Fast-growing annuals were selected for the study because their growth responses could be assessed over a major portion of the plant's life cycle and in as short a period as 8 wk. Plants were grown in eight hemi-spherical glasshouses, programmed to track outside ambient conditions and provide a replicated experimental design. Treatments comprised (i) current ambient [CO2 ] and temperature, (ii) elevated [CO2 ] (ambient+34 kPa), and ambient temperature (iii) ambient [CO2 ] and elevated temperature (ambient+3°C) and (iv) elevated [CO2 ] and elevated temperature (T°Celev ). All five species responded positively to [CO2 ]elev , although the response was statistically significant for only one, Poa annua L. Averaged over all five species, [CO2 ]elev increased total plant biomass by 25% (P=0·005) at 56 d, reflecting a proportionally greater increase in leaf and stem mass relative to root weight. Elevated [CO2 ] had no effect on leaf area, either at the individual species level or overall. Elevated T°C, by contrast, had little effect on shoot growth but increased root mass on average by 43% and leaf area by 22%. Few interactions between elevated [CO2 ] and T°C were observed, with the CO2 response generally greater at elevated than ambient T°C. Both [CO2 ]elev and T°Celev resulted in a transient increase in relative growth rate, (rgr), during the first 14 d exposure and a 3°C increase in temperature had no effect on the duration of the response. CO2 stimulation of growth operated through a sustained increase in net assimilation rate. (nar), although the potential benefit to rgr was offset by a concurrent decline in leaf area ratio (lar), as a result of a decrease in leaf area per unit leaf mass (sla). The response to T°Celev was generally opposite of that to [CO2 ]elev . For example, T°Celev increased lar through an increase in sla and this, rather than any effect on nar, was the major factor responsible for the stimulation of rgr. Allometric analysis of CO2 effects revealed that changes in allocation observed at individual harvests were due solely to changes associated with plant size. Elevated T°C, by contrast, had a direct effect on allocation patterns to leaves, with an increase in leaf area expansion relative to whole plant mass during the initial stages of growth and subsequent increased allocation of biomass away from leaves to other regions of the plant. No change in the allometric relation between roots and shoots were observed at either elevated [CO2 ] or T°C. We conclude, therefore, that allocation of biomass and morphological characteristics such as sla, are relatively insensitive to [CO2 ], at least when analysed at the whole-plant level, and where changes have been observed, these are the product of comparing plants of the same age but different size.

Pharmacological characterization of dopamine receptors in the corpus allatum of Manduca sexta larvae.

Dopamine receptors previously identified in corpora allata (CA) of Manduca sexta last instars on the basis of dopamine effects on JH (juvenile hormone)/JH acid biosynthesis and cyclic AMP (cAMP) accumulation, were characterized pharmacologically. For this study, a broad spectrum of agonists or antagonists of D1, D2, D3 or D4 dopamine receptors, together with the dopamine metabolite N-acetyl-dopamine, other neurotransmitters and their agonists/antagonists, were tested for their effects on gland activity and cAMP production. The lack of effect of other neurotransmitters supports the specificity of the effect of dopamine and the dopamine specificity of the receptors. Only the D2 receptor antagonist spiperone had a potent effect on JH biosynthesis and cAMP formation by CA taken on day 0 of the last stadium, when dopamine stimulates both activities and thus appears to be acting via a D1-like receptor. Several other D2 receptor antagonists, and D1, D2/D1 and D4,3/D2 receptor antagonists were less effective. Thus, the D1-like receptor of the Manduca CA appears to be distinct pharmacologically from vertebrate D1 receptors. By contrast, a number of D2 agonists/antagonists had a significant effect on JH acid biosynthesis and cAMP production by the CA from day 6 of the last stadium, when dopamine inhibits both activities and thus appears to be acting via a D2-like receptor. Certain D1-specific agonists/antagonists were equally effective. The Manduca D2-like receptor therefore bears some pharmacological resemblance to vertebrate D2 receptors. N-acetyl dopamine acted as a dopamine agonist with day 6 CA, the first identified function for an N-acetylated biogenic amine in insects. Dopamine was found to have the same differential affect on the formation of cAMP in homogenates of day 0 and day 6 brains as it did with CA, and in the same concentration range. Dopamine receptor agonists/antagonists affecting cAMP formation by day 0 and day 6 CA homogenates had similar effects with brain homogenates. By contrast, dopamine only stimulated cAMP formation by homogenates of day 0 and day 6 abdominal or ventral nerve cord. These results suggest that D1- and D2-like dopamine receptors of Manduca are regionally as well as temporally localized.

Influences of population size and woodland area on bird species distributions in small woods.

Distributions of individual bird species in 151 small woods (size range 0.02-30 ha) were investigated in 3 consecutive years during which the abundance of certain species varied markedly. Relationships between the probabilities of certain bird species breeding and woodland area were described using incidence functions derived from logistic regression analysis. In general, for species which were largely dependent on woodland and seldom occurred in other habitats (such as hedgerows and gardens), the probability of breeding approached 100% only for woods of 10 ha and more, whereas species with less stringent habitat requirements occurred in the majority of woods, including those of 1 ha and less. The sensitivity of incidence functions to changes in regional abundance and the size distribution of the study woods was examined. For some species, distribution patterns could not be distinguished from those expected if pairs had been distributed in proportion to woodland area (random placement), but the majority did not conform to random placement in at least 1 of the 3 years. This nonconformity was consistent across all 3 years for some species, such as wren (Troglodytes troglodytes), despite substantial fluctuations in population sizes between years, while for others, such as robin (Erithacus rubecula), distribution patterns changed with changes in regional abundance. The results suggested that some species, such as wren and blackbird (Turdus merula), preferred small woods, while other species, such as chiffchaff (Phylloscopus collybita), preferred large woods. For several other species, including robin, great tit (Parus major), long-tailed tit (Aegithalos caudatus) and marsh tit (P. palustris), small woods appeared to be sub-optimal under at least some conditions.

The effect of variation in calcium intake on the growth of wood mice and bank voles.

Calcium intake by wild rodents varies with season and habitat. This may have important ecological consequences; several studies have suggested that calcium availability may limit growth and reproduction. We studied the effect on growth of varying the calcium intake of captive wood mice Apodemus sylvaticus (L.) and bank voles Clethrionomys glareolus (Schreber 1780). To determine whether effects observed in the laboratory could be detected in free-living animals, we also compared the body weights and lengths of free-living animals on calcium-poor gritstone areas with those of rodents on calcium-rich limestone habitats where the dietary calcium concentration was between 2 and 5 times higher. Captive wood mice fed high calcium (0.87%) diet grew at the same rate as mice fed low calcium (0.30%) diet but continued growing for longer, thereby achieving higher asymptotic weights. In contrast, captive bank voles fed the high calcium diet grew more slowly and had lower asymptotic weights than voles fed the low calcium diet. As expected from the laboratory growth study, the higher calcium intake of free-living wood mice on the limestone was associated with greater body size compared with mice on the gritstone. However, bank voles were also larger on the limestone, even though high calcium intake impaired growth in captive animals. The contrast between wood mice and bank voles in the effects of calcium on growth, the reason why impaired growth may not be apparent in bank voles from calcium-rich habitats and the ecological significance of these results are discussed.

Comparison of mutagen accumulation in 3 estuarine species using the salmonella/microsome activation system.

3 Estuarine organisms- oysters (Crassostrea virginica), sea squirts (Mogulla sp.), and shrimp (Peneaus sp.)-were examined for Ames test detectable levels of mutagens. Whole-tissue extracts of these organisms were made and tested using S. Typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538, with and without S9 activation. Positive results were obtained with sea squirts and shrimp extracts. Activation was not necessary to show activity. Toxicity was encountered with oyster extracts. Histidine, a possible source of false positives, was eliminated from shrimp extracts using XAD-2 resin and thick-layer chromatography.

Natural products as insecticides: the biology, biochemistry and quantitative structure-activity relationships of spinosyns and spinosoids.

The spinosyns, a novel family of insecticidal macrocyclic lactones, are active on a wide variety of insect pests, especially lepidopterans and dipterans. The biological activity of a mixture (spinosad; Tracer, Spin-Tor, Success) of the two most abundant spinosyns (spinosyns A and D) against pest insects is on a par with that of many pyrethroid insecticides. The spinosyns also exhibit a very favorable environmental and toxicological profile, and possess a mode of action that appears unique, with studies to date suggesting that both nicotinic and gamma-aminobutryic acid receptor functions are altered in a novel manner. Compared to pyrethroids such as cypermethrin, spinosyn A is slow to penetrate into insect larvae such as tobacco budworm larvae (Heliothis virescens); however, once inside the insect, spinosyn A is not readily metabolized. To date, more than 20 spinosyns and more than 800 spinosoids (semi-synthetic analogs) have been isolated or synthesized, respectively. Artificial neural network-based quantitative structure activity relationship (QSAR) studies for the spinosyns suggested that modification of the 2',3',4'-tri-O-methylrhamnosyl moiety could improve activity and several spinosoids incorporating these modifications exhibited markedly improved lepidopteran activity compared to spinosad. Multiple linear regression-based QSAR studies also suggest that whole molecule properties such as CLogP and MOPAC dipole moment can explain much of the biological activity observed for the spinosyns and closely related spinosoids.

Recent advances in the chemistry of spinosyns.

The spinosyns are a new class of fermentation-derived insect control agents that are effective against a variety of chewing insect pests. The successful introduction of spinosad into the agricultural marketplace represents an important milestone in the use of natural products for commercial pest control. The development of a natural product presents additional limitations relative to a synthetic material. While the latter affords some degree of control in building appropriate physical attributes such as photostability, a natural product, designed to function in a different environment, is often less suited for traditional spray applications. Despite its intrinsic photolability, spinosad is stable enough to perform under field conditions. In an effort to generate analogs with improved physical characteristics, we have developed a variety of conditions for selectively modifying different portions of the molecule, and we have discovered analogs with greater activity against a broader spectrum of pests. The inability to translate improved greenhouse activity to actual field conditions resulted in a detailed study of the effects of formulations and crystallinity on biological activity. Through this effort, measurably improved field performance of synthetic spinosyn analogs relative to the natural product have now been observed.

Bioassay for detecting active site insensitivity in horn fly (Diptera: Muscidae) larvae.

A bioassay was used to detect active site insensitivity (knock-down resistance [kdr]) in pyrethroid resistant larvae of the horn fly, Haematobia irritans (L.). The larvae of the resistant population had KD50's 42.0-, 28.1- and 29.2-fold greater to permethrin, fenvalerate and lambda-cyhalothrin, respectively, compared with the susceptible population. In filter paper bioassays, resistant adult horn flies were 17 to 39.1 times less susceptible to the pyrethroids than susceptible adults at LC50. These results further document active site insensitivity as the major mechanism of pyrethroid resistance in the horn fly.