Suffering in silence: How COVID-19 school closures inhibit the reporting of child maltreatment.

To combat the spread of COVID-19, many primary and secondary schools in the United States canceled classes and moved instruction online. This study examines an unexplored consequence of COVID-19 school closures: the broken link between child maltreatment victims and the number one source of reported maltreatment allegations-school personnel. Using current, county-level data from Florida, we estimate a counterfactual distribution of child maltreatment allegations for March and April 2020, the first two months in which Florida schools closed. While one would expect the financial, mental, and physical stress due to COVID-19 to result in additional child maltreatment cases, we find that the actual number of reported allegations was approximately 15,000 lower (27%) than expected for these two months. We leverage a detailed dataset of school district staffing and spending to show that the observed decline in allegations was largely driven by school closures. Finally, we discuss policy implications of our findings for the debate surrounding school reopenings and suggest a number of responses that may mitigate this hidden cost of school closures.

Similar response patterns to topical minoxidil foam 5% in frontal and vertex scalp of men with androgenetic alopecia: a microarray analysis.

BACKGROUND: There are regional variations in the scalp hair miniaturization seen in androgenetic alopecia (AGA). Use of topical minoxidil can lead to reversal of miniaturization in the vertex scalp. However, its effects on other scalp regions have been less well studied. OBJECTIVES: To determine whether scalp biopsies from men with AGA show variable gene expression before and after 8 weeks of treatment with minoxidil topical foam 5% (MTF) vs. placebo. METHODS: A placebo-controlled double-blinded prospective pilot study of MTF vs. placebo was conducted in 16 healthy men aged 18-49 years with Hamilton-Norwood type IV-V thinning. The subjects were asked to apply the treatment (active drug or placebo) to the scalp twice daily for 8 weeks. Stereotactic scalp photographs were taken at the baseline and final visits, to monitor global hair growth. Scalp biopsies were taken at the leading edge of hair loss from the frontal and vertex scalp before and after treatment with MTF and placebo, and microarray analysis was performed using the Affymetrix GeneChip HG U133 Plus 2.0. RESULTS: Global stereotactic photographs showed that MTF induced hair growth in both the frontal and vertex scalp of patients with AGA. Regional differences in gene expression profiles were observed before treatment. However, MTF treatment induced the expression of hair keratin-associated genes and decreased the expression of epidermal differentiation complex and inflammatory genes in both scalp regions. CONCLUSIONS: These data suggest that MTF is effective in the treatment of both the frontal and vertex scalp of patients with AGA.

Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants.

Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended.

Does poor sleep quality affect skin ageing?

BACKGROUND: Sleep is important for growth and renewal of multiple physiological systems. The effects of chronic poor sleep quality on human skin function and visible signs of ageing have not been elucidated. AIM: To evaluate the effect of chronic poor sleep quality on measures of skin health and ageing. Self-perceived satisfaction with appearance was also assessed. METHODS: 60 healthy caucasian women, who were categorized as poor quality sleepers [Pittsburg Sleep Quality Index (PSQI) > 5, sleep duration ≤ 5 h] or good quality sleepers (PSQI ≤ 5, sleep duration 7-9 h). A validated clinical tool, SCINEXA(TM) , was used to assess intrinsic and extrinsic skin ageing. Dark under-eye circles were evaluated using standardized photos. Measurement of in vivo transepidermal water loss (TEWL) was used to assess recovery of the skin barrier after tape stripping. Subjects were exposed to simulated solar ultraviolet light, and recovery from erythema was monitored. Subjects also completed a questionnaire evaluating self-perception of attractiveness. RESULTS: Good sleepers had significantly lower intrinsic skin ageing scores by SCINEXA(TM) . At baseline, poor sleepers had significantly higher levels of TEWL. At 72 h after tape stripping, good sleepers had 30% greater barrier recovery compared with poor sleepers. At 24 h after exposure to ultraviolet light, good sleepers had significantly better recovery from erythema. Good sleepers also reported a significantly better perception of their appearance and physical attractiveness compared with poor sleepers. CONCLUSIONS: This study indicates that chronic poor sleep quality is associated with increased signs of intrinsic ageing, diminished skin barrier function and lower satisfaction with appearance.

The effect of vitrification of immature bovine oocytes to the subsequent in vitro development and gene expression.

Immature bovine oocytes were vitrified using the cryotop method and their post-warming survivability and capability to undergo in vitro maturation, fertilization and subsequent embryonic development were evaluated. In addition throughout the embryonic 2-cell, 4-cell, morula and blastocyst stages, the expression of four developmentally important genes (Cx43, CDH1, DNMT1 and HSPA14) was analysed using the real-time polymerase chain reaction (PCR). Immature oocytes (n = 550) were randomly assigned to non-vitrified (fresh) or cryotop vitrification groups using ethylene glycol (EG) with 1,2 propanediol (PROH) or dimethylsulphoxide (DMSO). After warming, oocytes survivability, embryo cleavage and embryonic developmental rates were not statistically different between the two cryoprotectants groups. However, the DMSO group had a lower (P < 0.05) oocyte maturation rate compared with the fresh and PROH groups. For morula and blastocyst rates, the DMSO group achieved a lower (P < 0.05) morula rate compared with the fresh group, while at the blastocyst stage, there were no differences between fresh and both cryoprotectants groups. For molecular analysis, at the 4-cell stage, most studied genes showed an inconsistent pattern of expression either from the PROH or DMSO groups. Noteworthily, these differences were limited at the morula and blastocyst stages. In conclusion, the cryotop method is sufficient for vitrification of immature bovine oocytes, both for embryonic developmental competence and at the molecular level. Moreover, PROH showed some advantage over DMSO as a cryoprotectant.

OPTIMISATION OF TOTAL RNA EXTRACTION FROM BOVINE OOCYTES AND EMBRYOS FOR GENE EXPRESSION STUDIES AND EFFECTS OF CRYOPROTECTANTS ON TOTAL RNA EXTRACTION.

Gene expression is required for understanding bovine oocytes meiotic maturation as well as the potential of embryonic development. In the present study a standardized reagent protocol for total RNA extraction was designed for bovine oocytes and embryos, which is considered specific and less expensive. For such purpose oocytes (n = 795) recovered from about 80 ovaries were divided in three groups: Group 1 modified Trizol (MTP, n = 355); Group 2 Guanidinium thiocyanate protocol (GNTC, n = 140) and Group 3 Commercial Kit protocol (CKP, n = 60). Oocytes belonging to group 1 (n = 100) and 3 (n = 20) were subjected to vitrification using two cryoprotectants 1,2 propandiol (PROH) or Dimethylsulfoxide (DMSO). The 240 remaining oocytes were divided into 3 groups in which 100 were used, in fresh, for in vitro fertilization, and 140 oocytes were vitrified using PROH (n = 70) and DMSO (n = 70) as cryoprotectants, being then fertilized in vitro after thawing. Embryos were used nine days after fertilization. Gene amplification (SDHA, (GAPDH and DNMT1) was performed in oocytes, and gene quantification (DNMT1) in in vitro produced embryos at the stage of blastocyst (n = 10). Efficiency of the extraction was further compared. The purity of all samples to different protocols ranged from 1.10 to 1.25 for GNTC protocol; from 2.05 to 2.63 for the CKP and from 1.50 to 2.11 for the developed MTP, being the last one nearest to the expected purity levels for RNA samples (1.7 to 2.0). On average, for 30 fresh oocytes, from spectrophotometer readings, total RNA concentration was 127.8 ± 9.3 ng µl(-1) for MTP, against 46.4 ± 9.5 ng µl(-1) from CKP and 476 ± 12.9 ng µl(-1) for GNTC protocol. Using the MTP to evaluate RNA in 30 vitrified/thawed oocytes, resulted in a total RNA concentration of 61.3 ± 3.3 ng µl(-1) and 40.0 µ 12.4 ng µ(-1), respectively for DMSO and PROH. Regarding total RNA concentration and purity, in blastocyst stage, more purity was observed in DMSO as compared to PROH (1.8 vs 1.2) (p < 0.05). Better results were also observed on the MTP for gene amplification when compared with the other protocols. For gene quantification, the proposed protocol quantified DNMT1 gene with PCR efficiency (0.933) after normalization against GAPDH and SDHA. Amplification and quantification of genes proved specificity and efficiency of the MTP over the other protocols.

Gas chromatography/tandem mass spectrometry method for the simultaneous analysis of 19 brominated compounds in environmental and biological samples.

A methodology for the simultaneous analysis of eight polybrominated diphenyl ethers (PBDEs); eight methoxylated PBDEs (MeO-PBDEs); and three emerging flame retardants, hexabromobenzene (HBB), pentabromoethyl benzene (PBEB), and decabromodiphenyl ethane (DBDPE) by gas chromatography coupled to tandem mass spectrometry (GC-MS-MS) was developed for two environmental matrices (sediment and sludge) and three biological matrices (fish, dolphin blubber, and bird eggs). The use of selective reaction monitoring (SRM) allows a high selectivity, which is critical in the analysis of complex samples like blubber. Analytical parameters such as linearity, reproducibility, or accuracy were evaluated. Method limits of detection and quantification were evaluated and compared with GC-EI-MS and GC-NCI-MS. Method detection limits were valid for the environmental analysis in all cases, with values between 0.01 and 1.65 ng/g dw for sediment, 0.05 and 2.78 ng/g dw for sludge, 0.04 and 10.6 ng/g lw for fish, 0.01 and 1.11 ng/g lw for dolphin blubber, and 0.03 and 3.20 ng/g lw for bird eggs. The developed method was applied to five samples of each matrix. PBDEs were detected in all samples, while MeO-PBDEs were only detected in dolphin blubber. DBDPE was detected in sediment and sludge.

Screening and pathways to maternal mental health care in a South African antenatal setting.

In low-resource settings, a stepped care approach is necessary to screen and provide care for pregnant women with mental health problems. This study sought to identify screening items that were most robust at differentiating women experiencing psychological distress and requiring counselling [assessed by screening with the Edinburgh Postnatal Depression Scale (EPDS) and a Risk Factor Assessment (RFA)] from those with a psychiatric disorder as diagnosed by a psychiatrist. Case records of women in an antenatal mental health service in Cape Town were reviewed. Composite scores and individual items on screening scales (EPDS, RFA) of participants who qualified for counselling (n = 308) were compared to those of participants who were diagnosed with a psychiatric disorder (n = 58). All participants with a psychiatric disorder were diagnosed with either depression or anxiety disorders. These participants had higher mean scores on the EPDS and RFA than those who qualified for counselling (p < 0.01). Logistic regression and ROC analyses suggested that the best items to distinguish women with depression or anxiety from those qualifying for counselling were 'I have felt sad and miserable', 'I am not pleased about being pregnant' and 'I have had serious depression, panic attacks or problems with anxiety before' (sensitivity 0.655, specificity 0.750 for this combination of three items). A small number of items may be useful in screening for mental illness in pregnancy which requires higher levels of care. Such screening may contribute to a more efficient stepped care approach.

Effect of bovine ovarian tissue vitrification on the structural preservation of antral follicles.

This study was performed to evaluate the structural preservation of antral follicles after bovine ovarian tissue vitrification using histological analysis. Ovaries (n = 30) of slaughtered cows were cut into small fragments using a scalpel blade, and the ovarian tissues were randomly assigned to vitrification using 15% dimethyl sulphoxide (DMSO) and 15% ethylene glycol (EG) and fresh tissues (control) groups. For histological evaluations, fresh and post-thawing ovarian tissues were immediately fixed, serially sectioned into 5-µm sections and stained with haematoxylin and eosin (H&E). Nine serial sections per fragment were subjected for morphological assessment. The diameter of the antral follicles was determined and classified into four groups: 1 (≤1 mm), 2 (>1-2 mm), 3 (>2-3 mm) and 4 (>3-4 mm). Then, follicular morphology was evaluated in relation to atresia and categorized into seven grades: Grade A (healthy follicle); Grades B, C and D (early atresia); Grades E and F (moderate atresia); and Grade G (advanced atresia). The results revealed that small diameters of antral follicles (1 and 2 mm) were more susceptible for cryoinjury. The normal follicular morphology (Grade A) was not affected by vitrification throughout follicle diameters. Nevertheless, some damage features were monitored after vitrification. In conclusion, the morphological structure of bovine antral follicles could be successfully preserved by ovarian tissue vitrification.

Increased plasma concentration of vascular endothelial growth factor in patients with atopic dermatitis and its relation to disease severity and platelet activation.

BACKGROUND: Overproduction of vascular endothelial growth factor (VEGF) in atopic dermatitis (AD) lesions has previously been observed. It is also known that platelet is an important source of VEGF and platelet factor 4 (PF-4), a potential marker of AD severity. AIM: To evaluate concentrations of VEGF and its soluble receptors (sVEGF-R1 and sVEGF-R2) in the plasma of AD patients and to examine its possible correlation with disease severity and plasma concentrations of PF-4, a platelet activation marker. METHODS: Plasma concentrations of VEGF and its receptors and levels of PF-4 were measured by an immunoenzymatic assay in 51 AD patients and in 35 healthy non-atopic controls. The severity of the disease was evaluated using the eczema area and severity index. RESULTS: AD patients showed significantly increased VEGF and PF-4 plasma concentrations as compared with the controls. Plasma concentrations of sVEGF-R1 and sVEGF-R2 did not differ between the groups. There were no remarkable correlations between plasma VEGF concentration and disease severity or between VEGF and PF-4 concentration. CONCLUSIONS: This study shows that plasma concentration of VEGF may be increased in patients suffering from AD. It seems that plasma VEGF concentration is not a useful marker of disease severity and, apart from platelets, other cells might also release the cytokine.

Dechlorane Plus and related compounds in aquatic and terrestrial biota: a review.

Dechlorane Plus, dechlorane 602, dechlorane 603 and dechlorane 604 are flame retardants that have been used for a long time as a substitute for mirex, but they have not been noticed as environmental contaminants until recently (2006). Regardless of their large molecular size and very high lipophilicity (log K(OW) > 9), Dechlorane Plus and related compounds have been detected in different aquatic and terrestrial species, supporting their bioaccumulation and biomagnification. Moreover, some studies showed different behaviour of the syn-Dechlorane Plus and anti-Dechlorane Plus isomers in the environment and different biomagnification factors in biota. This review describes the different analytical approaches applied to the determination of Dechlorane Plus and related compounds. Moreover, a summary of their levels in aquatic and terrestrial biota, as well as in humans, is presented, showing also current research results on their bioaccumulation and biomagnification potential. Finally, isomer-specific bioaccumulation of Dechlorane Plus is also discussed.

SNP identification and polymorphism analysis in exon 2 of the horse myostatin gene.

The myostatin gene (MSTN) belongs to the TGF-ß superfamily of secreted growth and differentiation factors and is responsible for embryonic and adult skeletal muscle development. In this study, exon 2 of the MSTN gene, which encodes part of the TGF-ß pro-peptide, was sequenced in 332 horses of 20 different breeds and compared with the horse MSTN gene sequence deposited in GenBank. The sequences obtained revealed the presence of 11 haplotypes represented by 10 variable nucleotide mutations, eight of them corresponding to amino acid sequence changes. This gene shows a high variability when compared with other genes. This might be an indication that some breeds have the same ancestry but different pressures of selection.

Quantitative trait loci associated with chemical composition of the chicken carcass.

Major objectives of the poultry industry are to increase meat production and to reduce carcass fatness, mainly abdominal fat. Information on growth performance and carcass composition are important for the selection of leaner meat chickens. To enhance our understanding of the genetic architecture underlying the chemical composition of chicken carcasses, an F(2) population developed from a broiler × layer cross was used to map quantitative trait loci (QTL) affecting protein, fat, water and ash contents in chicken carcasses. Two genetic models were applied in the QTL analysis: the line-cross and the half-sib models, both using the regression interval mapping method. Six significant and five suggestive QTL were mapped in the line-cross analysis, and four significant and six suggestive QTL were mapped in the half-sib analysis. A total of eleven QTL were mapped for fat (ether extract), five for protein, four for ash and one for water contents in the carcass using both analyses. No study to date has reported QTL for carcass chemical composition in chickens. Some QTL mapped here for carcass fat content match, as expected, QTL regions previously associated with abdominal fat in the same or in different populations, and novel QTL for protein, ash and water contents in the carcass are presented here. The results described here also reinforce the need for fine mapping and to perform multi-trait analyses to better understand the genetic architecture of these traits.

Successful cutaneous delivery of the photosensitizer silicon phthalocyanine 4 for photodynamic therapy.

BACKGROUND: Photodynamic therapy (PDT) has been shown to be effective in the treatment of malignancies of a variety of organ systems, including the lungs, bladder, gastrointestinal tract and skin. Cutaneous lesions serve as ideal targets of PDT because of the accessibility of the skin to light. To achieve optimum results, the photosensitizer must be delivered effectively into the target layers of the skin within a practical timeframe, via noninvasive methods. AIM: To determine whether topical application of a second-generation photosensitizer, silicon phthalocyanine (Pc) 4 [SiPc(OSi(CH3)2 (CH2)3 N(CH3)2)(OH)], results in effective penetration of the skin barrier. METHODS: Penetration of Pc 4 was evaluated using standard Franz-type vertical diffusion cell experiments on surrogate materials (silicone membranes) and laser-scanning confocal microscopy of normal skin biopsy samples from human volunteers. RESULTS: The Franz diffusion data indicate that Pc 4 formulated in an ethanol/propylene glycol solution (70/30%, v/v) can penetrate the membrane at a flux that is appreciable and relatively invariant. Using the same formulation, Pc 4 uptake could be detected in human skin via laser-scanning confocal microscopy. CONCLUSION: After topical application, Pc 4 is absorbed into the epidermis in as little as 1 h, and the absorption increased with increasing time and dose. Pc 4 can be effectively delivered into human skin via topical application. The data also suggest that the degree of penetration is time- and dose-dependent.

QTL for percentage of carcass and carcass parts in a broiler x layer cross.

An F2 experimental population, developed from a broiler layer cross, was used in a genome scan of QTL for percentage of carcass, carcass parts, shank and head. Up to 649 F2 chickens from four paternal half-sib families were genotyped with 128 genetic markers covering 22 linkage groups. Total map length was 2630 cM, covering approximately 63% of the genome. QTL interval mapping using regression methods was applied to line-cross and half-sib models. Under the line-cross model, 12 genome-wide significant QTL and 17 suggestive linkages for percentages of carcass parts, shank and head were mapped to 13 linkage groups (GGA1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 14, 18 and 27). Under the paternal half-sib model, six genome-wide significant QTL and 18 suggestive linkages for percentages of carcass parts, shank and head were detected on nine chicken linkage groups (GGA1, 2, 3, 4, 5, 12, 14, 15 and 27), seven of which seemed to corroborate positions revealed by the previous model. Overall, three novel QTL of importance to the broiler industry were mapped (one significant for shank% on GGA3 and two suggestive for carcass and breast percentages on GGA14 and drums and thighs percentage on GGA15). One novel QTL for wings% was mapped to GGA3, six novel QTL (GGA1, 3, 7, 8, 9 and 27) and suggestive linkages (GGA2, 4, and 5) were mapped for head%, and suggestive linkages were identified for back% on GGA2, 11 and 12. In addition, many of the QTL mapped in this study confirmed QTL previously reported in other populations.

PDT in squamous cell carcinoma of the skin.

Topical photodynamic therapy (PDT) has been demonstrated to be an effective and safe treatment option for pre-malignancies such as actinic keratoses (AK) and Bowen's disease (BD), with an increasing amount of evidence indicating good long term outcomes. Studies comparing PDT to other options such as cryotherapy and 5-fluorouracil generally demonstrate that PDT is equal to or better than these therapies with respect to patient satisfaction, cosmesis, and efficacy for AK and BD. While there are studies using squamous cell carcinoma (SCC) cells to elucidate the cellular and molecular mechanisms of PDT, this therapy is currently not indicated for treating SCC and surgery is still the first line of therapy. There has been special interest in using PDT to prevent warts, basal cell carcinoma, AK, and BD in solid organ transplant recipients, as these skin lesions are more common in immunosuppressed patients, and trials have been somewhat successful and very promising. Pain remains an obstacle for some patients and techniques such as nerve blocks, cooling packs, and hydration have been attempted to mitigate pain with an overall reduction in pain scores. Optimizing PDT is still a priority and the delivery of pro-drug as well as induction of cellular differentiation are being explored as ways to improve the efficacy of PDT. Perhaps the most interesting use of PDT in treating SCC is the potential for a tumor-specific vaccine, which is currently being developed.

Mixed infection involving Actinomyces, Aggregatibacter, and Fusobacterium species presenting as perispinal tumor.

A representative case in which a polymicrobial infection involving Fusobacterium nucleatum, Actinomyces israelii and Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans was initially diagnosed as malignancy in an edentulous patient. Additional history obtained after the nature of the syndrome was elucidated revealed that he had had his two remaining teeth extracted four months prior to this episode.

Photoprotection with clothing and sunscreens.

Skin cancer is an ever-expanding global health issue. UV radiation is the main etiological agent of most types of skin cancer. Photoprotection is critical to in skin cancer prevention. Sunscreens and physical barriers are the two primary photoprotective measures. This review summarizes current options in photoprotection, including physical barrier such as shade and clothing as well as sunscreens. In addition we look at how these photoprotective measures have influenced skin cancer rates and what can be done to improve the efficacy of existing photoprotective agents and devices.

Trends in invasive disease due to Candida species following heart and lung transplantation.

Although invasive candidiasis (IC) causes significant morbidity and mortality in patients who undergo heart, lung, or heart-lung transplantation, a systematic study in a large cohort of thoracic organ transplant recipients has not been reported to date. Clinical and microbiological data were reviewed for 1305 patients who underwent thoracic organ transplantation at Stanford University Medical Center between 1980 and 2004. We identified and analyzed 76 episodes of IC in 68 patients (overall incidence 5.2% per patient).The incidence of IC was higher in lung (LTx) and heart-lung transplant (HLTx) recipients as compared with heart transplant (HTx) recipients (risk ratio [RR] 1.7, 95% confidence interval [CI] 1.1-2.7).The incidence of IC decreased over time in all thoracic organ transplant recipients, decreasing from 6.1% in the 1980-1986 time period to 2.1% in the 2001-2004 era in the HTx recipients, and from 20% in the 1980-1986 period to 1.8% in the 2001-2004 period in the LTx and HLTx recipients.The most common site of infection differed between the HTx and LTx cohorts, with bloodstream or disseminated disease in the former and tracheobronchitis in the latter. IC in the first year after transplant was significantly associated with death in both HTx (RR 2.9, 95% CI 1.8-4.6, P=0.001) and LTx and HLTx patients (RR 3.0, 95% CI 1.9-4.6, P<0.001). The attributable mortality from IC decreased during the 25-year period of observation, from 36% to 20% in the HTx recipients and from 39% to 15% in the LTx and HLTx recipients. There were a significant number of cases caused by non-albicans Candida species in all patients, with a trend toward higher mortality in the HTx group. In conclusion, the incidence and attributable mortality of IC in thoracic organ transplant recipients has significantly declined over the past 25 years.The use of newer antifungal agents for prophylaxis and treatment, the decrease in the incidence of cytomegalovirus disease, and the use of more selective immunosuppression, among other factors, may have been responsible for this change.

Quantitative trait loci for performance traits in a broiler x layer cross.

An F(2) resource population, derived from a broiler x layer cross, was used to map quantitative trait loci (QTL) for body weights at days 1, 35 and 41, weight gain, feed intake, feed efficiency from 35 to 41 days and intestinal length. Up to 577 F(2) chickens were genotyped with 103 genetic markers covering 21 linkage groups. A preliminary QTL mapping report using this same population focused exclusively on GGA1. Regression methods were applied to line-cross and half-sib models for QTL interval mapping. Under the line-cross model, eight QTL were detected for body weight at 35 days (GGA2, 3 and 4), body weight at 41 days (GGA2, 3, 4 and 10) and intestine length (GGA4). Under the half-sib model, using sire as common parent, five QTL were detected for body weight at day 1 (GGA3 and 18), body weight at 35 days (GGA2 and 3) and body weight at 41 days (GGA3). When dam was used as common parent, seven QTL were mapped for body weight at day 1 (GGA2), body weight at day 35 (GGA2, 3 and 4) and body weight at day 41 (GGA2, 3 and 4). Growth differences in chicken lines appear to be controlled by a chronological change in a limited number of chromosomal regions.