Auxin and strigolactone signaling are required for modulation of Arabidopsis shoot branching by nitrogen supply.

The degree of shoot branching is strongly affected by environmental conditions, such as nutrient availability. Here we demonstrate that nitrate limitation reduces shoot branching in Arabidopsis (Arabidopsis thaliana) both by delaying axillary bud activation and by attenuating the basipetal sequence of bud activation that is triggered following floral transition. Ammonium supply has similar effects, suggesting that they are caused by plant nitrogen (N) status, rather than direct nitrate signaling. We identify increased auxin export from active shoot apices, resulting in increased auxin in the polar auxin transport stream of the main stem, as a likely cause for the suppression of basal branches. Consistent with this idea, in the auxin response mutant axr1 and the strigolactone biosynthesis mutant more axillary growth1, increased retention of basal branches on low N is associated with a failure to increase auxin in the main stem. The complex interactions between the hormones that regulate branching make it difficult to rule out other mechanisms of N action, such as up-regulation of strigolactone synthesis. However, the proposed increase in auxin export from active buds can also explain how reduced shoot branching is achieved without compromising root growth, leading to the characteristic shift in relative biomass allocation to the root when N is limiting.

FHY3 promotes shoot branching and stress tolerance in Arabidopsis in an AXR1-dependent manner.

The transposase-related transcription factor FAR-RED ELONGATED HYPOCOTYL3 (FHY3) promotes seedling de-etiolation in far-red light, which is perceived by phytochrome A (phyA). In this role, FHY3 indirectly mediates the nuclear import of light-activated phyA, which triggers downstream transcriptional responses. Here, we present genetic evidence for additional roles of FHY3 in plant development and growth. New fhy3 alleles were isolated as suppressors of max2-1 (more axillary branching2-1), a strigolactone-insensitive mutant characterised by highly branched shoots. Branching suppression by fhy3, in both wild-type and max2-1 backgrounds, resulted from inhibition of axillary bud outgrowth. Additional roles in axillary meristem initiation were revealed in the revoluta (rev) fhy3 double mutant, with fhy3 enhancing rev mutant defects in axillary shoot meristem formation, as well as in floral meristem maintenance. fhy3 also affected embryonic and floral patterning with low penetrance, and displayed oxidative stress-related phenotypes of retarded leaf growth and of cell death. The fhy3 phenotypes of axillary bud outgrowth suppression and of stress-induced leaf growth retardation both required the AUXIN-RESISTANT1 gene, and are independent of phyA. Consistent with the recent discovery that FHY3 regulates many Arabidopsis promoters, our results suggest much wider roles for FHY3 in growth and development, either in concert with, or beyond, light signalling.

Strigolactones enhance competition between shoot branches by dampening auxin transport.

Strigolactones (SLs), or their derivatives, were recently demonstrated to act as endogenous shoot branching inhibitors, but their biosynthesis and mechanism of action are poorly understood. Here we show that the branching phenotype of mutants in the Arabidopsis P450 family member, MAX1, can be fully rescued by strigolactone addition, suggesting that MAX1 acts in SL synthesis. We demonstrate that SLs modulate polar auxin transport to control branching and that both the synthetic SL GR24 and endogenous SL synthesis significantly reduce the basipetal transport of a second branch-regulating hormone, auxin. Importantly, GR24 inhibits branching only in the presence of auxin in the main stem, and enhances competition between two branches on a common stem. Together, these results support two current hypotheses: that auxin moving down the main stem inhibits branch activity by preventing the establishment of auxin transport out of axillary branches; and that SLs act by dampening auxin transport, thus enhancing competition between branches.

Cell wall composition contributes to the control of transpiration efficiency in Arabidopsis thaliana.

To identify loci in Arabidopsis involved in the control of transpirational water loss and transpiration efficiency (TE) we carried out an infrared thermal imaging-based screen. We report the identification of a new allele of the Arabidopsis CesA7 cellulose synthase locus designated AtCesA7(irx3-5) involved in the control of TE. Leaves of the AtCesA7(irx3-5) mutant are warmer than the wild type (WT). This is due to reduced stomatal pore widths brought about by guard cells that are significantly smaller than the WT. The xylem of the AtCesA7(irx3-5) mutant is also partially collapsed, and we suggest that the small guard cells in the mutant result from decreased water supply to the developing leaf. We used carbon isotope discrimination to show that TE is increased in AtCesA7(irx3-5) when compared with the WT. Our work identifies a new class of genes that affects TE and raises the possibility that other genes involved in cell wall biosynthesis will have an impact on water use efficiency.

MAX1 encodes a cytochrome P450 family member that acts downstream of MAX3/4 to produce a carotenoid-derived branch-inhibiting hormone.

The plant shoot body plan is highly variable, depending on the degree of branching. Characterization of the max1-max4 mutants of Arabidopsis demonstrates that branching is regulated by at least one carotenoid-derived hormone. Here we show that all four MAX genes act in a single pathway, with MAX1, MAX3, and MAX4 acting in hormone synthesis, and MAX2 acting in perception. We propose that MAX1 acts on a mobile substrate, downstream of MAX3 and MAX4, which have immobile substrates. These roles for MAX3, MAX4, and MAX2 are consistent with their known molecular identities. We identify MAX1 as a member of the cytochrome P450 family with high similarity to mammalian Thromboxane A2 synthase. This, with its expression pattern, supports its suggested role in the MAX pathway. Moreover, the proposed enzymatic series for MAX hormone synthesis resembles that of two already characterized signal biosynthetic pathways: prostaglandins in animals and oxilipins in plants.

Monitoring microemboli during cardiopulmonary bypass with the EDAC quantifier.

Gaseous emboli may be introduced into the bypass circuit both from the surgical field and during perfusionist interventions. While circuits provide good protection against massive air embolism, they do not remove gaseous microemboli (GME) from the bypass circuit. The purpose of this preliminary study is to assess the incidence of GME during bypass surgery and determine if increased GME counts were associated with specific events during bypass surgery. In 30 cases divided between 15 coronary artery bypass grafts and 15 valve repairs, GME were counted and sizedt the three locations on the bypass circuit using the EDAC" Quantifier (Luna Innovations, Roanoke, VA). A mean of 45,276 GME were detected after the arterial line filter during these 30 cases, with significantly more detected (p = .04) post filter during valve cases (mean = 72,137 +/- 22,113) than coronary artery bypass graft cases (mean = 18,416 +/- 7831). GME detected post filter were significantly correlated in time with counts detected in the venous line (p < .001). Specific events associated with high counts included the initiation of cardiopulmonary bypass, heart manipulations, insertion and removal of clamps, and the administration of drugs. Global factors associated with increased counts post filter included higher venous line counts and higher post reservoir/bubble trap counts. The mean number of microemboli detected during bypass surgery was much higher than reported in other studies of emboli incidence, most likely due to the increased sensitivity of the EDAC Quantifier compared to other detection modalities. The results furthermore suggest the need for further study of the clinical significance of these microemboli and what practices may be used to reduce GME incidence. Increased in vitro testing of the air handling capability of different circuit designs, along with more clinical studies assessing best clinical practices for reducing GME activity, is recommended.

The identification of genes involved in the stomatal response to reduced atmospheric relative humidity.

Stomatal pores of higher plants close in response to decreases in atmospheric relative humidity (RH). This is believed to be a mechanism that prevents the plant from losing excess water when exposed to a dry atmosphere and as such is likely to have been of evolutionary significance during the colonization of terrestrial environments by the embryophytes. We have conducted a genetic screen, based on infrared thermal imaging, to identify Arabidopsis genes involved in the stomatal response to reduced RH. Here we report the characterization of two genes, identified during this screen, which are involved in the guard cell reduced RH signaling pathway. Both genes encode proteins known to be involved in guard cell ABA signaling. OST1 encodes a protein kinase involved in ABA-mediated stomatal closure while ABA2 encodes an enzyme involved in ABA biosynthesis. These results suggest, in contrast to previously published work, that ABA plays a role in the signal transduction pathway connecting decreases in RH to reductions in stomatal aperture. The identification of OST1 as a component required in stomatal RH and ABA signal transduction supports the proposition that guard cell signaling is organized as a network in which some intracellular signaling proteins are shared among different stimuli.

Young women and limits to the normalisation of condom use: a qualitative study.

Encouraging condom use among young women is a major focus of HIV/STI prevention efforts but the degree to which they see themselves as being at risk limits their use of the method. In this paper, we examine the extent to which condom use has become normalised among young women. In-depth interviews were conducted with 20 year old women from eastern Scotland (N=20). Purposive sampling was used to select a heterogeneous group with different levels of sexual experience and from different social backgrounds. All of the interviewees had used (male) condoms but only three reported consistent use. The rest had changed to other methods, most often the pill, though they typically went back to using condoms occasionally. Condoms were talked about as the most readily available contraceptive method, and were most often the first contraceptive method used. The young women had ingrained expectations of use, but for most, these norms centred only on their new or casual partners, with whom not using condoms was thought to be irresponsible. Many reported negative experiences with condoms, and condom dislike and failure were common, lessening trust in the method. Although the sexually transmitted infection (STI) prevention provided by condoms was important, this was seen as additional, and secondary, to pregnancy prevention. As the perceived risks of STIs lessened in relationships with boyfriends, so did condom use. The promotion of condoms for STI prevention alone fails to consider the wider influences of partners and young women's negative experiences of the method. Focusing on the development of condom negotiation skills alone will not address these issues. Interventions to counter dislike, method failure, and the limits of the normalisation of condom use should be included in STI prevention efforts.

Limits to modern contraceptive use among young women in developing countries: a systematic review of qualitative research.

BACKGROUND: Improving the reproductive health of young women in developing countries requires access to safe and effective methods of fertility control, but most rely on traditional rather than modern contraceptives such as condoms or oral/injectable hormonal methods. We conducted a systematic review of qualitative research to examine the limits to modern contraceptive use identified by young women in developing countries. Focusing on qualitative research allows the assessment of complex processes often missed in quantitative analyses. METHODS: Literature searches of 23 databases, including Medline, Embase and POPLINE(R), were conducted. Literature from 1970-2006 concerning the 11-24 years age group was included. Studies were critically appraised and meta-ethnography was used to synthesise the data. RESULTS: Of the 12 studies which met the inclusion criteria, seven met the quality criteria and are included in the synthesis (six from sub-Saharan Africa; one from South-East Asia). Sample sizes ranged from 16 to 149 young women (age range 13-19 years). Four of the studies were urban based, one was rural, one semi-rural, and one mixed (predominantly rural). Use of hormonal methods was limited by lack of knowledge, obstacles to access and concern over side effects, especially fear of infertility. Although often more accessible, and sometimes more attractive than hormonal methods, condom use was limited by association with disease and promiscuity, together with greater male control. As a result young women often relied on traditional methods or abortion. Although the review was limited to five countries and conditions are not homogenous for all young women in all developing countries, the overarching themes were common across different settings and contexts, supporting the potential transferability of interventions to improve reproductive health. CONCLUSION: Increasing modern contraceptive method use requires community-wide, multifaceted interventions and the combined provision of information, life skills, support and access to youth-friendly services. Interventions should aim to counter negative perceptions of modern contraceptive methods and the dual role of condoms for contraception and STI prevention should be exploited, despite the challenges involved.

Young women's continued use of oral contraceptives over other hormonal methods: findings from a qualitative study.

BACKGROUND: Long-acting reversible contraceptives (LARC) have become more commonly promoted in the UK, but most young women still rely on the contraceptive pill. Here, we describe young women's accounts of hormonal contraceptive use to explore why this might be the case. METHODS: In-depth interviews with twenty 20-year-old women from eastern Scotland in the UK. RESULTS: All but one woman reported use of the pill. It was the method they expected to use, sought out, and received. Belief in the pill's efficacy was maintained even when knowledge or experience of failure suggested otherwise. Only four women reported using alternative hormonal methods and only did so after experiencing unmanageable problems with the pill (side effects or forgetting to take it). All then discontinued use because of weight gain or dislike of menstrual suppression. CONCLUSIONS: Attempts to promote LARC must address these issues. Pill use can be unproblematic if managed well, and should continue to be promoted as an appropriate contraceptive for young women.

What explains between-school differences in rates of sexual experience?

BACKGROUND: Schools have the potential to influence their pupils' behaviour through the school's social organisation and culture, as well as through the formal curriculum. This paper provides the first attempt to explain the differences between schools in rates of reported heterosexual sexual experience amongst 15 and 16 year olds. It first examined whether variations in rates of sexual experience remained after controlling for the known predictors of sexual activity. It then examined whether these residuals, or 'school effects', were attributable to processes within the school, or were more likely to reflect characteristics of the neighbourhood. METHODS: Longitudinal survey data from 4,926 pupils in 24 Scottish schools were linked to qualitative and quantitative data on school processes including quality of relationships (staff-pupil, etc), classroom discipline, organisation of Personal and Social Education, school appearance and pupil morale. Multi-level modelling was used to test a range of models and the resulting 'school effects' were then interpreted using the process data. RESULTS: Overall, 42% of girls and 33% of boys reported experience of sexual intercourse, with rates by school ranging from 23% to 61%. When individual socio-economic and socio-cultural factors were taken into account the school variation dropped sharply, though pupils' attitudes and aspirations had little effect. There was very little correlation between boys' and girls' rates of sexual experience by school, after controlling for known predictors of sexual activity. Girls were more influenced by individual socio-economic factors than boys. School-level socio-economic factors were predictive even after taking account of individual socio-cultural factors, suggesting that the wider socio-economic environment further influenced young people's sexual experience. CONCLUSION: Importantly, school processes did not explain the variation between schools in sexual experience. Rather, the variation may have been due to neighbourhood culture.

Prevalence of anthelmintic resistance on sheep and goat farms in the southeastern United States.

OBJECTIVE: To determine prevalence of anthelmintic resistance on sheep and goat farms in the southeastern United States. DESIGN: Cross-sectional study. ANIMALS: Sheep and goats from 46 farms in 8 southern states, Puerto Rico, and St Croix in the US Virgin Islands. PROCEDURES: Parasite eggs were isolated from fecal samples, and susceptibility to benzimidazole, imidathiazole, and avermectin-milbemycin anthelmintics was evaluated with a commercial larval development assay. RESULTS: Haemonchus contortus was the most common parasite on 44 of 46 farms; Trichostrongylus colubriformis was the second most commonly identified parasite. Haemonchus contortus from 45 (98%), 25 (54%), 35 (76%), and 11 (24%) farms were resistant to benzimidazole, levamisole, ivermectin, and moxidectin, respectively. Resistance to all 3 classes of anthelmintics was detected on 22 (48%) farms, and resistance to all 3 classes plus moxidectin was detected on 8 farms (17%). CONCLUSIONS AND CLINICAL RELEVANCE: Findings provided strong evidence that anthelmintic resistance is a serious problem on small ruminant farms throughout the southeastern United States. Owing to the frequent movement of animals among regions, the prevalence of resistance in other regions of the United States is likely to also be high. Consequently, testing of parasite eggs for anthelmintic resistance should be a routine part of parasite management on small ruminant farms.

Young women under 16 years with experience of sexual intercourse: who becomes pregnant?

BACKGROUND: The UK has the highest rate of teenage pregnancies in western Europe. Although there is a large body of literature focusing on predictors of conception among this age group, almost all the work compares those young women who have become pregnant with their peers, regardless of whether or not their peers have experienced sexual intercourse. OBJECTIVE: To compare 16-year-old young women who have become pregnant with their peers who also have experience of sexual intercourse, but who have not conceived. DESIGN: Analysis of data from the baseline and follow-up surveys conducted as part of a trial of sex education. SETTING AND PARTICIPANTS: Female school students aged 14-16 years from the East of Scotland. MAIN RESULTS: Young age of self and partner, and non-use of contraception, all at first intercourse, are most strongly associated with pregnancy. CONCLUSIONS: Those who engage in sexual intercourse at a relatively young age will often have had more opportunity to become pregnant than those whose sexual debut comes later. Similarly, the fact that those who use contraception at first intercourse have been less likely to conceive than those who do not could reflect the overall patterns of contraceptive use: young women who have used contraception at each occasion of intercourse will have had less chance to conceive than those who have not. Having a young partner at first intercourse suggests that, if this pattern continues, the couple may lack the resources needed to prevent a pregnancy due to the immaturity of both partners.

Chlamydia trachomatis testing among 13-25-year-olds in non-genitourinary medicine settings.

OBJECTIVES: In this paper we examine Chlamydia trachomatis testing in settings other than genitourinary medicine (GUM) clinics, focusing on the factors associated with chlamydial infection and with postal testing. METHODS: Analysis of tests collected from young people aged 13-25 years (n = 4475) between May 2001 and June 2004 via postal testing kits, at a local sexual health clinic, and at further education colleges in Lothian, Scotland. RESULTS: 84.8% of the testers were female and 15.2% were male. 84 men (12.3%, 95% CI 10.1-15.0) and 403 women (10.6%, 95% CI 9.7-11.6) tested positive. The odds of a positive result was nearly doubled for postal and clinic testers, relative to college testers; and increased by 70% for 16-19-year-olds, compared with 13-15-year-olds. Postal testing was the main source for men (80.2%) while 46.1% of women used postal and 48.1% used clinic testing. Postal testing was significantly associated with age, sex and National Health Service (NHS) board area, with odds increasing with age, and lower odds among females than males, and among Lothian residents than those outwith this NHS board area. CONCLUSIONS: Substantial chlamydial infection was apparent among the young people in this study and positivity rates were highest among postal and clinic testers and those in the 16-19-year age group. While postal kits were the main source for men, and should be used to target them, the combination of this approach with continuing screening programmes in clinic settings would be most effective at targeting those most at risk.

Validation of the FAMACHA© system in South American camelids.

Haemonchus contortus resistant to multiple anthelmintics threaten the viability of the small ruminant industry in areas where this parasite is prevalent. In response to this situation, the FAMACHA© system was developed and validated for use with small ruminants as a way to detect clinical anemia associated with haemonchosis. Given that H. contortus and multiple anthelmintic resistance is a similar problem in camelids, the FAMACHA© system might also provide the same benefits. To address this need, a validation study of the FAMACHA© system was conducted on 21 alpaca and llama farms over a 2-year period. H. contortus was the predominant nematode parasite on 17 of the 21 farms (10 alpaca and 7 llama farms) enrolled in the study, based on fecal culture results. The FAMACHA© card was used to score the color of the lower palpebral (lower eye lid) conjunctiva on a 1-5 scale. Packed cell volume (PCV) values were measured and compared to FAMACHA© scores using FAMACHA© score cutoffs of ≥3 or ≥4 and with anemia defined as a PCV ≤15%, ≤17%, or≤20%. PCV was significantly associated with FAMACHA© score, fecal egg count (FEC), and body condition score (BCS), regardless of the FAMACHA© cutoff score or the PCV% chosen to define clinical anemia (p<0.01 in all cases). The use of FAMACHA© scores ≥3 and PCV ≥ 15% indicating anemia provided the best sensitivity (96.4% vs 92.9% for FAMACHA© ≥4), whereas FAMACHA scores ≥ 4 and PCV ≤20% provided the best specificity (94.2% vs 69.1% for FAMACHA© ≥3). The data from this study support the FAMACHA© system as a useful tool for detecting clinical anemia in camelids suffering from haemonchosis. Parameters for making treatment decisions based on FAMACHA© score in camelids should mirror those established for small ruminants.

Pathology of Haemonchus contortus in New World camelids in the southeastern United States: a retrospective review.

Most small ruminant farms in tropical climates are plagued by Haemonchus contortus, a hematophagous, abomasal parasite. Heavy burdens of this parasite can cause anemia, hypoproteinemia, weight loss, and mortality in susceptible animals. Haemonchus contortus is becoming a major health concern in New World camelids as well, namely llamas (Llama glama) and alpacas (Vicugna pacos), yet little research has been conducted regarding its prevalence or pathology in these species. Herein, we present a retrospective review of llamas and alpacas that were admitted to The University of Georgia Veterinary Teaching Hospital and Athens Diagnostic Laboratory between the years 2002 and 2013. Antemortem fecal egg count (FEC) estimates performed on 30 alpacas were negatively correlated with hematocrit, hemoglobin, and red blood cell count. Total protein was not significantly correlated with FEC. On postmortem examination, 55 of 198 camelids, including 2 from the aforementioned antemortem review, were infected with H. contortus, with llamas (42.6%) having a significantly higher infection rate than alpacas (22.2%). In 15.7% of the total cases, the parasite was the major cause of death. Common gross lesions included peritoneal, thoracic, and pericardial effusions, visceral pallor, subcutaneous edema, and serous atrophy of fat. Histologic lesions included centrilobular hepatic necrosis, hepatic atrophy, lymphoplasmacytic inflammation of the mucosa of the third gastric compartment (C3), extramedullary hematopoiesis in both the liver and spleen, and the presence of nematodes in C3. Our study emphasizes the importance of H. contortus diagnosis and herd monitoring in New World camelids, particularly llamas.

Root system architecture determines fitness in an Arabidopsis mutant in competition for immobile phosphate ions but not for nitrate ions.

Plant root systems often have complex branching patterns. Models indicate that a complex architecture is only required for the acquisition of immobile resources, such as phosphate; mobile ions, notably nitrate, can be effectively taken up by very restricted root systems. We have tested this prediction using the axr4 mutation of Arabidopsis thaliana, the principal phenotypic effect of which is to reduce the number of lateral roots. Arabidopsis thaliana is not a host for mycorrhizal fungi and so acquires all its nutrients through the root system. In both a pot experiment and a field experiment conducted under natural conditions for A. thaliana, we found that only phosphate, and not nitrate, affected the fitness of the mutant relative to the isogenic wild-type line, Columbia. These results confirm model predictions and have implications both for the evolution of complex root systems and for the design of efficient root systems for crops.

Unintentional injury during foreign travel: a review.

Unintentional injury is a global public health problem. In 1990, an estimated 5 million people worldwide died as a result of an injury or poisoning. This accounted for 10% of deaths from all causes that year, and over half of the estimated 900 million years of life lost in 1990 due to premature death. Although mortality rates for ischemic heart disease, cerebrovascular disease, and cancer are higher, the majority of people dying of these causes are elderly, with far fewer potential years of life to live. Reasons for the increasing public health importance of injury include the decline of infectious disease, the processes of urbanization, industrialization, motorization, and increased opportunities to travel.

A familial degenerative neuromuscular disease of Gelbvieh cattle.

A degenerative skeletal muscle disease with vascular, neurologic, and renal lesions and a probable familial distribution was identified in 4-20-month-old purebred Gelbvieh cattle. Thirteen affected animals were confirmed from 6 separate beef herds, with a mortality rate of 100%. Clinical signs in affected animals consisted of ataxia, weakness, and terminal recumbency. Gross and histologic muscle lesions were indicative of nutritional myopathy of ruminants, with a lack of myocardial lesions in most cases and only rare myocardial changes in a few animals. Acute to chronic lesions in most large skeletal muscle groups consisted of degeneration, necrosis, regeneration, fibrosis, and atrophy. Fibrinoid necrosis of arterioles was a common feature in multiple tissues. Lesions in the spinal cord white matter and peripheral nerves consisted of degeneration of the dorsal columns and axons, respectively. Changes in the kidneys consisted of chronic interstitial nephritis with fibrosis, hyaline droplet change and tubular epithelial vacuolar change and were most severe in the older calves. Intracytoplasmic myoglobin and iron were demonstrated within the hyaline droplets in degenerate renal cortical tubular epithelial cells. Vitamin E levels were deficient in most (6/7) of the animals tested. Investigation of the pedigree of affected animals revealed a common ancestry for all but 1 of the animals whose parentage could be traced. This investigation suggests that a hereditary metabolic defect, possibly involving antioxidant metabolism, could be responsible for this condition. Renal disease, possibly secondary to myoglobinuria, may be unique to this bovine condition.