Associations of intestinal helminth infections with health parameters of spring-migrating female lesser scaup (Aythya affinis) in the upper Midwest, USA.

Thousands of lesser scaup (Aythya affinis) die during spring and fall migrations through the upper Midwest, USA, from infections with Cyathocotyle bushiensis and Sphaeridiotrema spp. (Class: Trematoda) after ingesting infected intermediate hosts, such as non-native faucet snails (Bithynia tentaculata). The lesser scaup is a species of conservation concern and is highly susceptible to these infections. We collected female lesser scaup from spring migratory stopover locations throughout Illinois and Wisconsin and assessed biochemical and morphological indicators of health in relation to intestinal helminth loads. Helminth species diversity, total trematode abundance, and the infection intensities of the trematodes C. bushiensis and Sphaeridiotrema spp. were associated with percent body fat, blood metabolites, hematological measures, and an index of foraging habitat quality. Helminth diversity was negatively associated with percent body fat, albumin concentrations, and monocytes, whereas glucose concentrations displayed a slight, positive association. Total trematode abundance was negatively associated with blood concentrations of non-esterified fatty acids and albumin. Infections of C. bushiensis were positively related to basophil levels, whereas Sphaeridiotrema spp. infection intensity was negatively associated with packed cell volume and foraging habitat quality. Thus, commonly measured health metrics may indicate intestinal parasite infections and help waterfowl managers understand overall habitat quality. Intestinal parasitic loads offer another plausible mechanism underlying the spring condition hypothesis.

Spatiotemporal distributions of intestinal helminths in female lesser scaup Aythya affinis during spring migration from the upper Midwest, USA.

We examined the associations between intestinal helminth infracommunity structure and infection parameters and the age, size, and year and region of collection of 130 female lesser scaup (Aythya affinis) during their 2014-2015 spring migrations through the upper Midwest, USA. We identified a total of 647,174 individual helminths from 40 taxa, including 20 trematodes, 14 cestodes, 4 nematodes and 2 acanthocephalans parasitizing lesser scaup within the study area. Lesser scaup were each infected with 2-23 helminth taxa. One digenean, Plenosoma minimum, is reported for the first time in lesser scaup and in the Midwest. Mean trematode abundance and total helminth abundance was significantly less in 2015 than 2014, and we suspect that colder weather late in 2015 impacted the intermediate host fauna and caused the observed differences. Brillouin's species diversity of helminths was greatest in the northernmost region of the study area, which coincides with the range of a non-indigenous snail that indirectly causes annual mortality events of lesser scaup. While host age and size were not determined to be influential factors of helminth infracommunity structure, non-parametric ordination and permutational analysis of co-variance revealed that year and region of collection explained differences in helminth infracommunities. Our results suggest that spatiotemporal variations play an important role in the structure of intestinal helminth infracommunities found in migrating lesser scaup hosts, and may therefore impact host ability to build endogenous reserves at certain stopover locations in the Midwest.

Lysine partitioning in broiler breeders is not affected by energy or protein intake when fed at current industry levels.

A study was conducted to determine the effects of dietary energy and protein intake on the partitioning of lysine in broiler breeder hens. One hundred twenty-six broiler breeders were randomly assigned to 1 of 6 dietary treatments in a 2 (390, 450 kcal/d) × 3 (22, 24, 26 g of CP/d) fashion. Thirty-six hens were administered a daily oral dose of 15 mg of (15)N-Lys for a period of 2 wk or until first egg. After the 2-wk enrichment period, no isotopes were given for 2 d. After 2 d, a daily oral dose of 15 mg of (2)D4-Lys was administered until the 2nd, 3rd, and 4th egg (saved) after the initial (2)D4-Lys was given, at which point pectoralis muscle was sampled. Weeks 25, 29, and 45 were assessed. Isotopic enrichment of pectoralis muscle, egg yolk, and albumen was determined via gas chromatography-mass spectrometry. The (15)N-Lys was intended to represent endogenous lysine, whereas the (2)D4-Lys was intended to represent dietary lysine. Greater than 78% of all labeled lysine ((15)N and (2)D4-Lys) was found in breast muscle. Endogenous muscle was the main source of lysine for yolk formation at wk 25 and 45. Diet was the main source of lysine for albumen formation at wk 25 and 29. A consistent decrease in the (15)N-Lys in breast muscle from the 2nd to the 3rd egg was observed, while also seeing an increase in the (15)N-Lys in the egg from the 3rd to the 4th egg. No difference in the partitioning of lysine was determined by energy or protein intake at levels typical for the current poultry industry. Rather, age, and possibly rate of production, appear to be the main drivers of lysine partitioning in the broiler breeder hen.

The relationship between phosphorus retention and fibroblast growth factor 23 in broiler breeders.

Previous studies with broiler breeders indicate a P retention threshold when fed daily dietary levels of non-phytate P (NPP) exceeding 320 mg. Fibroblast growth factor 23 (FGF23) is a hormone secreted by osteocytes which modulates P retention and could be the biological agent which controls the P threshold in breeders. To evaluate the relationship between FGF23 and the P retention threshold, a 4-wk study with 32-wk-old breeders was conducted with 6 dietary treatments with daily NPP intake of 216 to 576 mg/d/h with increments of 80 mg/kg diet. The goals were 1) to elucidate how plasma FGF23 corresponds with the P retention threshold in broiler breeders and 2) to determine the amount of P for optimal egg production and bone health. Results showed that between daily 288 mg and 360 mg dietary NPP intake, P retention decreased from 33 to 26% but FGF23 levels increased from 130 pg/mL to 220 pg/mL with increasing NPP. The elevation of plasma FGF23 between the range of 288 mg to 360 mg dietary NPP/d intake suggests that FGF23 is related to the P retention threshold and may be the major hormone for regulating physiological P levels when intake of daily dietary P levels are increased above 288 mg NPP.

Efficacy of surgeon-performed, intra-operative ultrasound scan for localisation of parathyroid adenomas in patients with primary hyperparathyroidism.

BACKGROUND: In the UK, guidance recommends ultrasound scanning alone or in combination with sestamibi scintigraphy to guide surgery in patients with primary hyperparathyroidism. If an adenoma is localised on imaging, this can facilitate targeted or minimally invasive surgery. Surgeon-performed ultrasound scan on the operating table benefits from being performed on an anaesthetised patient with optimal positioning. The aim of this study was to investigate the efficacy of intra-operative, blinded, surgeon-performed ultrasound scan in localisation of parathyroid adenomas. METHODS: Prospective data were collected on consecutive patients undergoing surgery for primary hyperparathyroidism at a single tertiary centre from November 2019 to June 2021. Patients underwent blinded, surgeon-performed ultrasound scan under general anaesthesia immediately prior to surgery. Localisation results from pre-operative imaging and surgeon-performed ultrasound scan were then compared with the intra-operative findings. RESULTS: Forty-nine patients underwent surgery and were found to have single-gland disease. Sestamibi scintigraphy, radiologist-performed ultrasound scan and surgeon-performed ultrasound scan had sensitivities of 59.4, 43.75 and 73.8 per cent, respectively. Surgeon-performed ultrasound scan had a statistically significantly increased sensitivity compared with radiologist-performed ultrasound (p < 0.05). CONCLUSION: Intra-operative, surgeon-performed ultrasound scan is effective in localising parathyroid adenomas and may be a useful adjunct to facilitate minimally invasive parathyroid surgery.

An update on the management of thyroid nodules: rationalising the guidelines.

BACKGROUND: Guidance for the management of thyroid nodules has evolved over time, from initial evaluation based predominantly on clinical grounds to now including the established role of ultrasound and fine needle aspiration cytology in their assessment. There is, however, significant variation in the management of thyroid nodules depending on which national guidelines are followed. In addition, there are certain clinical situations such as pregnancy and paediatric thyroid nodules that have differing evaluation priorities. OBJECTIVES: This review aimed to provide an overview of currently accepted practices for the initial investigation and subsequent management of patients with thyroid nodules for the non-specialist. The review also addresses areas of variance between the systems in common clinical use, as well as newer, evolving technologies, including molecular testing in the evaluation of malignancy in thyroid nodules.

Parasite Prevalence in Feral Swine (Sus scrofa) from the Great Smoky Mountains National Park, USA.

Feral swine (Sus scrofa) are an introduced species to the Great Smoky Mountains National Park (GSMNP), US, and serve as carriers of several diseases that are considered a threat to other wildlife, domestic animals, and humans. During 2013 and 2015, fecal samples from 67 feral swine from the GSMNP within both Tennessee and North Carolina, US, were opportunistically collected as part of a feral swine removal program and submitted to the University of Tennessee College of Veterinary Medicine, Knoxville, Tennessee, for parasite screening by centrifugal sugar flotation. Ten taxa from the phyla Acanthocephala, Apicomplexa, and Nematoda were identified: Ascaris spp., Strongylid-type spp., Capillaria spp., Trichuris suis, Metastrongylus spp., Macracanthorhynchus spp., Coccidia, Sarcocystis spp., and Cryptosporidium spp. In 98.5% of samples, at least one parasite was found. No differences in parasite prevalence or species diversity were noted based on state of collection (Tennessee or North Carolina), sex, or age. The high prevalence of gastrointestinal parasites in these feral swine, some of which are zoonotic, represents a potential public health risk as well as a concern for free-range swine farmers.

Accuracy of physician and nurse practitioner colposcopy to effect improved surveillance of cervical cancer.

PURPOSE: To compare physician and nurse practitioner accuracy in recognizing cervical dysplasia during colposcopy. MATERIALS AND METHODS: A retrospective review was performed of cervical excisional biopsies from 2007 to 2009 performed by gynecologists and nurse practitioners in the same patient population. Cervical cone biopsy and loop electrosurgical excision procedure (LEEP) pathology were used as a gold standard compared to the previous colposcopy biopsies. RESULTS: Four hundred fifty-five patients qualified for the study. Patients were stratified according to age: under 30 years, 30-39, and 40 and above. For physicians, 77% of high-grade colposcopy biopsy results agreed with high-grade pathology on cone biopsy or LEEP. This was statistically similar to nurse practitioner results (p = 0.12). Likewise, there was no significant difference between physician and nurse practitioner accuracy within the various patient age strata. CONCLUSION: Colposcopy biopsy results compared to cone biopsy or LEEP results were statistically similar between gynecologists and nurse practitioners.

The effects of pullet body weight, dietary nonpyhtate phosphorus intake, and breeder feeding regimen on production performance, chick quality, and bone remodeling in broiler breeders.

A 3 × 2 × 2 factorial experiment, consisting of 52 hens per treatment, was conducted to determine the effects of pullet BW, dietary nonphytate phosphorus (NPP), and feeding regimen on performance, progeny quality, and bone remodeling. Cobb 500 broiler breeder pullets were reared to 3 different growth curves: 20% under, Cobb standard, and 20% over. Body weights were recorded weekly and feed adjustments made accordingly. At 21 wk, 624 hens were fed one of 2 breeder diets differing only in the amount of dietary NPP: 0.15 or 0.40%. A normal feeding regimen was appropriate for the particular growth curve; an alternative regimen considered the 3 growth curves together as a flock. At 24, 26, and 29 wk, blood was collected from 5 hens per treatment every 4 h over a 24-h period. Plasma samples were analyzed for total alkaline phosphatase, tartrate-resistant acid phosphatase, parathyroid hormone-related peptide, Ca, and inorganic P. Eggs per hen housed were diminished in hens fed the low dietary NPP and by low pullet target weight. Hens fed low dietary NPP also had lower egg weights but better eggshell quality. Mortality was significantly higher in hens fed low dietary NPP. Breeder tibia relative strength and ash were also significantly lower in hens fed low dietary NPP, regardless of the quantitative amount. Progeny tibia ash was not affected by any treatment. Total alkaline phosphatase responded to pullet BW, however by wk 29, total alkaline phosphatase also became sensitive to dietary NPP. The NPP by pullet BW interaction for tartrate-resistant acid phosphatase levels became significant by 29 wk, and pullet BW was significant at wk 24. The NPP by pullet growth curve interaction was also critical for plasma inorganic P levels throughout the sampling period. In summary, both 0.15% dietary NPP and reared pullets 20% under standard BW negatively affect egg production but do not impair progeny productivity. Body composition appears to be a main contributor in bone remodeling mechanisms, especially during the transition into egg production.

Is sonographic intra-nodular vascularity a reliable predictor of thyroid malignancy? A UK tertiary centre study.

OBJECTIVE: British Thyroid Association 2014 guidelines emphasised ultrasound assessment of nodules. One ultrasonographic differentiator of debatable relevance is intra-nodular vascularity. This is the first UK study conducted to address this question. METHODS: Ultrasound reports for thyroid surgery patients over 10 years were retrospectively reviewed. Reports documenting 'intra-nodular vascularity or flow' were analysed. Reports identifying peripheral vascularity only or no intra-nodular flow formed the control group. Concordance with final histology was used to determine the odds ratio for malignancy. RESULTS: A total of 306 patients were included, and 119 (38.9 per cent) nodules demonstrated intra-nodular vascularity. Of these, 60 (50.4 per cent) were malignant compared with 42 per cent in the control group. Intra-nodular vascularity was not a statistically significant predictor of malignancy with an odds ratio of 1.39 (p = 0.18, 95 per cent confidence interval, 0.86-2.23). CONCLUSION: Intra-nodular vascularity in isolation was not a reliable predictor of malignancy. This supports other world literature studies. Although intra-nodular flow should not be relied upon in isolation, interpretation in conjunction with other suspicious findings enhances the predictive value.

Mitochondrial growth and division during the cell cycle in HeLa cells.

The growth and division of mitochondria during the cell cycle was investigated by a morphometric analysis of electron micrographs of synchronized HeLa cells. The ratio of total outer membrane contour length to cytoplasmic area did not vary significantly during the cell cycle, implying a continuous growth of the mitochondrial outer membrane. The mean fraction of cytoplasmic area occupied by mitochondrial profiles was likewise found to remain constant, indicating that the increase in total mitochondrial volume per cell occurs continuously during interphase, in such a way that the mitochondrial complement occupies a constant fraction( approximately 10-11(percent)) of the volume of the cytoplasm. The mean area, outer membrane contour length, and axis ratio of the mitochondrial profiles also did not vary appreciably during the cell cycle; furthermore, the close similarity of the frequency distributions of these parameters for the six experimental time-points suggested a stable mitochondrial shape distribution. The constancy of both the mean mitochondrial profile area and the number of mitochondrial profiles per unit of cytoplasmic area was interpreted to indicate the continuous division of mitochondria at the level of the cell population. Furthermore, no evidence was found for the occurrence of synchronous mitochondrial growth and division within individual cells. Thus, it appears that, in HeLa cells, there is no fixed temporal relationship between the growth and division of mitochondria and the events of the cell cycle. A number of statistical methods were developed for the purpose of making numerical estimates of certain three-dimensional cellular and mitochondrial parameters. Mean cellular and cytoplasmic volumes were calculated for the six time-points; both exhibited a nonlinear, approx. twofold increase. A comparison of the axis ratio distributions of the mitochondrial profiles with theoretical distributions expected from random sectioning of bodies of various three-dimensional shapes allowed the derivation of an "average" mitochondrial shape. This, in turn, permitted calculations to be made which expressed the two-dimensional results in three-dimensional terms. Thus, the estimated values for the number of mitochondria per unit of cytoplasmic volume and for the mean mitochondrial volume were found to remain constant during the cell cycle, while the estimated number of mitochondria per cell increase approx. twofold in an essentially continuous manner.

Past glacial activity in the canadian high arctic.

Field observations on northeast Ellesmere Island indicate that the maximum advance of the northwest Greenland Ice Sheet was about 100 kilometers beyond its present margin. This occurred before the outermost Ellesmere Island ice advance, which took place more than 30,000 years before present (B.P.). Recession from the Ellesmere Island ice margin began at least 28,000 to 30,000 and possibly more than 35,000 years B.P. During this sequence of glacial events, significant land areas remained free of ice. The late Wisconsin ice extent along both northeast Ellesmere Island and northwest Greenland was extremely limited, leaving an ice-free corridor along Kennedy and Robeson channels. Recession from these ice margins is indicated by initial postglacial emergence around 8100 to 8400 years B.P. The relatively minor extent of late Wisconsin ice in the High Arctic probably reflects a period of extreme aridity occasioned by the buildup of the Laurentide Ice Sheet to the south.

Predicting nutrient digestibility and energy value for broilers.

Digestibility coefficients of nutrients, metabolizable energy (ME), net energy (NE) and the ratio of NE to ME (NE/ME) of 20 diets were measured in broiler chickens (1 to 21 d). Dietary nutrients were formulated to keep similar ME/nutrient ratios, except for dietary protein, fat, and fiber using corn, soybean meal, animal protein blend, barley, poultry oil and an enzyme mixture of xylanase, glucanase, and phytase. Digestibility coefficients of nutrients and ME were measured in battery cages under free-access of feed, while NE was measured in floor pens feeding 75% of recommended ME intake each day. NE for maintenance was calculated on basis of mean metabolic weight using a coefficient from a previous study and NE for gain was calculated by body protein and fat gains using dual-energy x-ray absorptiometry. Digestibility coefficients of protein and neutral detergent fiber (NDF) were curvilinearly related to dietary protein and NDF, respectively, while digestibility coefficients of fat and starch were linearly correlated to dietary fat and starch, respectively. The inclusion of enzymes increased the digestion coefficient of NDF to predict the digestibility of protein, NDF, fat, and starch. MEn/gross energy ratio averaged 72.5% and was correlated to protein, fat, NDF, and starch. ME values were accurately predicted from chemical characteristics, where best equations were obtained from digestible nutrients. Energetic efficiencies of ME were 72% (NE/MEn) and 68% (NE/ME) and varied by about 20 and 18%, respectively. Ratios of energetic efficiency were 68% for digestible carbohydrates; 86% for digestible fat; and 76% (NE/MEn) and 59% (NE/ME) for digestible protein. According to the lowest residual standard deviation the best nutrient components to predict energy were digestible nutrients for predicting ME values (41 kcal/kg); digestible protein intake, fecal organic matter, and body fat and protein for predicting heat increment values (111 kcal/kg); and combination of ME and crude nutrient for predicting NE values (140 kcal/kg).

Effect of body weight and energy intake on body composition analysis of broiler breeder hens.

A study was conducted to determine the effect of different feeding programs and energy intakes on the body composition of broiler breeders (BB) from 22 wk of age to 65 wk of age. Cobb 500 BB that had been reared using three growth curves: (1) the control group followed Cobb 500 guidelines (SBW) for target body weights (BW), (2) the second group target BW was 20% heavier (HBW) than the SBW group, and (3) the third group target BW was 20% lighter (LBW) than the SBW group. At 21 wk of age, pullets from each growth curve were assigned to be fed one of six treatments. Diets were formulated and allocated to provide 330, 360, 390, 420, 450, or 480 kcal ME/hen/d and 24 g protein/hen/d, at peak intake. Body composition (lean mass, fat mass, and mineral content) was measured by dual-energy x-ray absorptiometry throughout the production period. Significantly, greater (P < 0.05) amounts of fat mass and lower amounts of lean mass were evident at the beginning of the production period for HBW hens compared with SBW and LBW hens. Higher levels of energy intake also affected body composition. Namely, fat deposition was greatest throughout the production period in hens consuming 480 kcal/d at peak intake (P < 0.05). Critically, fluctuations to lean and fat mass throughout the production period are suggestive of underlying regulatory processes. Specifically, hens appears to maintain consistent lean mass throughout the production period with a coefficient of variation of <12% across all birds. The results of this study provide important BB body composition information from management and nutrition studies that showed the dynamics of body composition change during the production period.

Non-cellulosic polysaccharide content in feed ingredients and ileal and total tract non-cellulosic polysaccharide digestibility in 21- and 42-day-old broilers fed diets with and without added composite enzymes.

An initial study profiled non-cellulosic polysaccharide (NCP) levels in feed ingredient samples-corn, soybean meal (SBM), whole soybean, and distillers dried grains with solubles (DDGS). A separate NCP digestibility assay was performed in broilers at day 21 (grower phase) and day 42 (finisher phase) fed corn-soy based diets with and without composite enzymes (phytases, multi-carbohydrases, and proteases). Negative control (NC), NC + composite enzymes (NC+E), and positive control (PC) diets were tested. Negative control and NC + E diets were isocaloric, 3,020 kcal/kg ME at grower phase and 3,026 kcal/kg ME at finisher phase. Positive control diet was formulated to meet the Cobb standard nutrient specifications. Diets, pooled digesta, and excreta samples from all treatment diets were collected from 21- and 42-day-old birds and NCP content analyzed as soluble NCP (S-NCP) and insoluble NCP (I-NCP) fractions. Digestibility coefficient (DC) values were determined for all dietary treatments for both the feeding periods. Results from the ingredient analysis showed NCP levels of ∼7 to 10% in corn samples, ∼8 to 11% in SBM samples, ∼11 to 14% (including pectin level) in whole soybean, and ∼12 to 17% in DDGS samples, suggesting variation (P < 0.05) in NCP levels existed within ingredient samples. Digestibility assays showed that enzyme treated (NC + E) diet improved DC values at day 21 from 6 to 10 units and 6 to 9 units for ileal and total tract collection, respectively, for I-NCP fraction (P < 0.05) compared to DC values for NC or PC diets. The ileal DC values at day 42 were not different between treatment diets (∼0.6) but total tract DC values improved 9 to 11 units for broilers fed NC + E diet compared to NC or PC diets. Higher DC values for S-NCP were observed for all treatments for both feeding periods (∼0.7-ileal and ∼0.8-total tract) compared to DC values for I-NCP. Overall, the use of supplemental enzymes in corn-soy-based diets showed improvement in total NCP digestion.

Effect of dietary nutrients on ileal endogenous losses of threonine, cysteine, methionine, lysine, leucine and protein in broiler chicks.

An isotope dose technique was utilized (i) to determine endogenous amino acid (AA) and protein losses and (ii) to propose adjusted values for AA requirements. The endogenous flow rate was calculated from the pool of enrichment in plasma AA, assuming similitude to enrichment of endogenous AA. In experiment 1, chicks were orally administered D4-lysine at 2% of estimated lysine intake from 16 to 24 days to find the isotopic steady state of the atom percent excess (APE) of lysine for plasma and jejunal and ileal digesta. The APE of D4-lysine in plasma, jejunal digesta and ileal digesta reached the isotopic steady state at 5.5, 3.4 and 2.0 days, respectively, by using the broken-line model. It was assumed that the isotopic steady state at 5 days identified for D4-lysine is also representative for the 15N-labeled AA. In experiment 2, chicks were fed diets from 1 to 21 days with increasing levels of fat (6%, 8%, 12%, 13% extract ether), protein (26%, 28.5%, 31% CP) or fiber (14%, 16%, 18% NDF) by adding poultry fat, soybean meal, blended animal protein or barley. Chicks were orally administered 15N-threonine, 15N-cysteine, 15N-methionine, 15N-lysine and 15N-leucine at 2% of estimated daily intake for 5 days from 17 to 21 days of age. Dietary nutrients influenced endogenous losses (EL), where dietary fat stimulated EL of lysine (P=0.06), leucine and protein (P=0.07); dietary protein enhanced EL of leucine and protein; and finally the dietary fiber increased EL of leucine. Dietary nutrients also affected apparent ileal digestibility (AID). Dietary fat increased AID of cysteine but decreased AID of lysine. Dietary protein reduced AID of protein, threonine, lysine and leucine, and similarly dietary fiber decreased AID of protein, threonine, methionine, lysine and leucine. In contrast, dietary fat or protein did not affect real ileal digestibility (RID) of protein and AA except threonine and leucine. The dietary fiber reduced the RID of protein, threonine and leucine. This indicate that variations of some endogenous AA and protein losses due to dietary nutrients almost eliminates the effects of RID, and thus the EL coming from the body should be utilized to adjust the AA requirement instead of changing the true digestible nutrients of ingredients. The present data suggest that 5 days' feeding labeled AA was enough to reach the isotopic steady state and AA requirements should be adjusted when additional dietary protein, fat or fiber is fed.

Mechanisms of lipid mobilization towards egg formation in broiler breeder hens using stable isotopes.

The contribution of dietary, mobilized, or newly synthesized fatty acids in yolk formation at different periods of egg production was determined. In an initial experiment, a single dose of 13C-linoleic acid was administered to pullets at the onset of egg production and their presence in follicles determined over the subsequent 10 days. In a second experiment, pullets were fed a daily 15 mg dose of U-13C-glucose beginning 2 wk prior to sexual maturity through the end of the experimental period. A 50 mg meal of U-13C-linoleic acid was orally administered approximately 10 d prior to sexual maturity (defined as first egg) representing body linoleic acid. Upon each hen's first egg, each bird received a 25 mg meal of 2D31-linoleic acid representing dietary linoleic acid. All eggs were collected for the next 10 days. The incorporation of labeled linoleic acid and palmitic acid in egg yolk was then determined using GC-MS. This process was repeated at peak production and at 45 wk of age. At sexual maturity, the deposition of labeled palmitic acid in the yolk was higher compared with its deposition at peak production and 45 wk of age. The deposition of both 13C- and 2D31-linoleic acid increased with hen age. These results suggest that dietary and tissue linoleic acid is utilized to a greater extent in older hens and that lipogenesis (synthesis of palmitic acid) plays a larger role at sexual maturity in the young hen.

Cell cycle control of cell morphogenesis in Caulobacter.

In Caulobacter crescentus, morphogenic events, such as cytokinesis, the establishment of asymmetry and the biogenesis of polar structures, are precisely regulated during the cell cycle by internal cues, such as cell division and the initiation of DNA replication. Recent studies have revealed that the converse is also true. That is, differentiation events impose regulatory controls on other differentiation events, as well as on progression of the cell cycle. Thus, there are pathways that sense the assembly of structures or the localization of complexes and then transduce this information to subsequent biogenesis or cell cycle events. In this review, we examine the interplay between flagellar assembly and the C. crescentus cell cycle.