Coexistence of superconductivity and antiferromagnetism in (Li0.8Fe0.2)OHFeSe.

Iron selenide superconductors exhibit a number of unique characteristics that are helpful for understanding the mechanism of superconductivity in high-Tc iron-based superconductors more generally. However, in the case of AxFe2Se2 (A = K, Rb, Cs), the presence of an intergrown antiferromagnetic insulating phase makes the study of the underlying physics problematic. Moreover, FeSe-based systems intercalated with alkali metal ions, NH3 molecules or organic molecules are extremely sensitive to air, which prevents the further investigation of their physical properties. It is therefore desirable to find a stable and easily accessible FeSe-based superconductor to study its physical properties in detail. Here, we report the synthesis of an air-stable material, (Li0.8Fe0.2)OHFeSe, which remains superconducting at temperatures up to ~40 K, by means of a novel hydrothermal method. The crystal structure is unambiguously determined by a combination of X-ray and neutron powder diffraction and nuclear magnetic resonance. Moreover, antiferromagnetic order is shown to coexist with superconductivity. This synthetic route opens a path for exploring superconductivity in other related systems, and confirms the appeal of iron selenides as a platform for understanding superconductivity in iron pnictides more broadly.

Emergent Kondo Lattice Behavior in Iron-Based Superconductors AFe_{2}As_{2} (A=K, Rb, Cs).

Here, we experimentally study the origin of d-electron heavy fermion (HF) behavior in iron-based superconductors (FeSCs) AFe_{2}As_{2} (A=K, Rb, Cs). Nuclear magnetic resonance on ^{75}As reveals a universal coherent-incoherent crossover with a characteristic temperature T^{*}. Below T^{*}, a so-called "Knight shift anomaly" is first observed in FeSCs, which exhibits a scaling behavior similar to f-electron HF materials. Furthermore, the scaling rule also regulates the manifestation of magnetic fluctuation. These results undoubtedly support an emergent Kondo lattice scenario for the d-electron HF behavior, which qualifies the AFe_{2}As_{2} (A=K, Rb, Cs) as d-electron HF superconductors.

Ultralow-Frequency Collective Compression Mode and Strong Interlayer Coupling in Multilayer Black Phosphorus.

The recent renaissance of black phosphorus (BP) as a two-dimensional (2D) layered material has generated tremendous interest, but its unique structural characters underlying many of its outstanding properties still need elucidation. Here we report Raman measurements that reveal an ultralow-frequency collective compression mode (CCM) in BP, which is unprecedented among similar 2D layered materials. This novel CCM indicates an unusually strong interlayer coupling, and this result is quantitatively supported by a phonon frequency analysis and first-principles calculations. Moreover, the CCM and another branch of low-frequency Raman modes shift sensitively with changing number of layers, allowing an accurate determination of the thickness up to tens of atomic layers, which is considerably higher than previously achieved by using high-frequency Raman modes. These findings offer fundamental insights and practical tools for further exploration of BP as a highly promising new 2D semiconductor.

Evolution of High-Temperature Superconductivity from a Low-T_{c} Phase Tuned by Carrier Concentration in FeSe Thin Flakes.

We report the evolution of superconductivity in an FeSe thin flake with systematically regulated carrier concentrations by the liquid-gating technique. With electron doping tuned by the gate voltage, high-temperature superconductivity with an onset at 48 K can be achieved in an FeSe thin flake with T_{c} less than 10 K. This is the first time such high temperature superconductivity in FeSe is achieved without either an epitaxial interface or external pressure, and it definitely proves that the simple electron-doping process is able to induce high-temperature superconductivity with T_{c}^{onset} as high as 48 K in bulk FeSe. Intriguingly, our data also indicate that the superconductivity is suddenly changed from a low-T_{c} phase to a high-T_{c} phase with a Lifshitz transition at a certain carrier concentration. These results help to build a unified picture to understand the high-temperature superconductivity among all FeSe-derived superconductors and shed light on the further pursuit of a higher T_{c} in these materials.

Pressure-Induced Electronic Transition in Black Phosphorus.

In a semimetal, both electrons and holes contribute to the density of states at the Fermi level. The small band overlaps and multiband effects engender novel electronic properties. We show that a moderate hydrostatic pressure effectively suppresses the band gap in the elemental semiconductor black phosphorus. An electronic topological transition takes place at approximately 1.2 GPa, above which black phosphorus evolves into a semimetal state that is characterized by a colossal positive magnetoresistance and a nonlinear field dependence of Hall resistivity. The Shubnikov-de Haas oscillations detected in magnetic field reveal the complex Fermi surface topology of the semimetallic phase. In particular, we find a nontrivial Berry phase in one Fermi surface that emerges in the semimetal state, as evidence of a Dirac-like dispersion. The observed semimetallic behavior greatly enriches the material property of black phosphorus and sets the stage for the exploration of novel electronic states in this material.

Screening of polymorphisms located in the FGF20 and TMEM175 genes in North Chinese Parkinson's disease patients.

Genome-wide association studies have reported numerous susceptibility loci for Parkinson's disease (PD). However, there have been few replication studies examining these loci in northern Chinese populations. To evaluate the relationships among 3 polymorphic markers located in the fibroblast growth factor 20 and transmembrane protein 175 genes and the genetic susceptibility to PD in northern Chinese subjects, 2 single nucleotide polymorphisms, and 1 insertion/deletion marker (rs591323 in FGF20; rs6599388 and rs142821586 in transmembrane protein 175 near the G-associated kinase/diacylglycerol kinase theta region) were investigated in 313 PD patients and 318 matched controls. Mismatched multiplex polymerase chain reaction-restriction fragment length polymorphism analysis as well as sequence-specific primer polymerase chain reaction and restriction fragment length polymorphism assays were performed. The genotypic frequency of rs591323 differed significantly between the patient and control groups; however, neither rs6599388 nor rs142821586 was associated with PD. We corrected the Hardy-Weinberg disequilibrium for rs6599388, which was previously reported to be common in 4 Asian descent populations into equilibrium status by simultaneously genotyping rs6599388 and rs142821586. In summary, we found that rs591323 was associated with PD but rs6599388 and rs142821586 were not associated with PD in a northern Chinese population.

Effects of supplemental zinc source and level on antioxidant ability and fat metabolism-related enzymes of broilers.

The objective of the present study was to investigate the effects of dietary supplemental Zinc (Zn) source and level on antioxidant ability and fat metabolism-related enzymes of broilers. Dietary treatments included the Zn-unsupplemented corn-soybean meal basal diet (control) and basal diets supplemented with 60, 120, or 180 mg Zn/kg as Zn sulfate, Zn amino acid chelate with a weak chelation strength of 6.5 quotient of formation (Qf) (11.93% Zn) (Zn-AA W), Zn proteinate with a moderate chelation strength of 30.7 Qf (13.27% Zn) (Zn-Pro M), or Zn proteinate with an extremely strong chelation strength of 944.0 Qf (18.61% Zn) (Zn-Pro S). The results showed that dietary supplemental Zn increased (P < 0.01) Zn contents in the liver, breast, and thigh muscles of broilers, and up-regulated mRNA expressions of copper and Zn containing superoxide dismutase (CuZnSOD) and metallothioneins (MT) in the liver (P < 0.01) and thigh muscle (P < 0.05), and also enhanced (P < 0.05) CuZnSOD activities in the breast and thigh muscles, which exerted antioxidant ability and a decreased malondialdehyde (MDA) level in the liver (P < 0.01) and breast and thigh muscles (P < 0.05) of broilers. Furthermore, supplemental Zn increased activities of malate dehydrogenase (MDH) and lipoprotein lipase (LPL) in the abdominal fat (P < 0.05), and fatty acid synthetase (FAS) and LPL in the liver (P < 0.01), which were accompanied with up-regulation (P < 0.01) of the mRNA expressions levels of these enzymes in the abdominal fat and liver of broilers. Dietary Zn source, and an interaction between Zn source and level, had no effects on any measurements. It is concluded that dietary Zn supplementation improved Zn status and resulted in promoting antioxidant ability and activities and gene expressions of fat metabolism-related enzymes of broilers regardless of Zn source and level, and the addition of 60 mg Zn/kg to the corn-soybean meal basal diet (a total dietary Zn of approximately 90 mg/kg) was appropriate for improving the above aspects of broilers.

Enhancement of focusing energy of ultra-thin planar lens through plasmonic resonance and coupling.

A metal-insulator-metal (MIM) structure which is used to enhance the focusing energy of planar lens is developed in this work. The top of the MIM structure is formed by circularly arranged V-shaped nanoantennas whose double resonance effect makes it possible for light to obtain great phase changes within an ultra-thin area. The middle and bottom of the structure is medium and gold film layer respectively. This structure produces plasmonic coupling between the antenna layer and gold film, thus reducing Ohmic loss and enhancing the effect of plasmonic excitation. When the distance between the antenna layer with a thickness of 30 nm and gold film is 88 nm, and the thickness of gold film is 20 nm, the enhancement of plasmonic coupling reaches to the strongest when the focusing intensity is 1.33 times higher than the lens only. With the advantages of small size, ultra-thin, great phase changes and high-efficient focusing ability, the enhanced plasmonic coupling lens structure can be widely applied in photoetching, and integrated optics.

Relative bioavailability of iron proteinate for broilers fed a casein-dextrose diet.

An experiment was carried out to determine the bioavailability of organic Fe as Fe proteinate (Alltech, Nicholasville, KY) relative to inorganic Fe source (FeSO4•7H2O) for broiler chicks fed a casein-dextrose diet. A total of 448 1-d-old Arbor Acres commercial male broiler chicks were randomly allotted to 1 of 8 replicate cages (8 chicks per cage) for each of 7 treatments in a completely randomized design involving a 2 × 3 factorial arrangement of treatments with 2 Fe sources (Fe proteinate and Fe sulfate) and 3 levels of added Fe (10, 20, or 40 mg of Fe/kg) plus a Fe-unsupplemented control diet containing 4.56 mg of Fe/kg by analysis. Feed and distilled-deionized water were available ad libitum for an experimental phase of 14 d. At 14 d of age, blood samples were collected for testing hemoglobin (Hb) and hematocrit, and calculating total body Hb Fe, whereas liver and kidney samples were excised for Fe analyses. The results showed that ADG, ADFI, blood Hb, hematocrit, and total body Hb Fe and Fe concentrations in liver and kidney increased linearly (P < 0.0001), whereas mortality decreased linearly (P < 0.0001) as dietary Fe level increased. However, only blood Hb concentration and total body Hb Fe differed (P < 0.004) between the 2 Fe sources. Based on slope ratios from the multiple linear regression of Hb concentration and total body Hb Fe on daily intake of analyzed dietary Fe, the bioavailability of Fe proteinate relative to FeSO4•7H2O (100%) was 117 and 114%, respectively (P < 0.009). The results indicated that blood Hb concentration and total body Hb Fe were sensitive indices in reflecting differences in bioavailability among different Fe sources, and Fe proteinate was significantly more available to broilers than inorganic Fe sulfate in enhancing Hb concentration and total body Hb Fe.

Hybrid phase-change plasmonic crystals for active tuning of lattice resonances.

Tunable lattice resonances are demonstrated in a hybrid plasmonic crystal incorporating the phase-change material Ge2Sb2Te5 (GST) as a 20-nm-thick layer sandwiched between a gold nanodisk array and a quartz substrate. Non-volatile tuning of lattice resonances over a range Δλ of about 500 nm (1.89 µm to 2.27 µm) is achieved experimentally via intermediate phase states of the GST layer. This work demonstrates the efficacy and ease of resonance tuning via GST in the near infrared, suggesting the possibility to design broadband non-volatile tunable devices for optical modulation, switching, sensing and nonlinear optical devices.

Effect of intravenously injected zinc on tissue zinc and metallothionein gene expression of broilers.

1. The effect of intravenously injected zinc (Zn) on tissue Zn concentrations and pancreas metallothionein (MT) gene expression in broilers was investigated to detect differences in the tissue utilisation of Zn from different Zn sources. 2. A total of 432 male chickens were randomly allotted on d 22 post-hatch to one of nine treatments in a completely randomised design. Chickens were injected with either a 0.9% (w/v) NaCl solution (control) or a saline solution supplemented with Zn sulphate or one of three organic Zn chelates with weak (Zn-AA W), moderate (Zn-Pro M) or strong (Zn-Pro S) chelation strengths at two injected Zn dosages calculated according to two Zn absorbability levels (6 and 12%). 3. Bone and pancreas Zn concentrations, pancreas MT mRNA levels and MT concentrations increased on d 6 and 12 after Zn injections as the injected Zn dosages increased. Chickens injected with the Zn-Pro S had lower bone Zn concentration than those injected with the Zn-Pro M or Zn-AA W on d 6 after injections. However, no differences among Zn sources were observed in bone Zn concentration on d 12 after injections, pancreas Zn concentrations, pancreas MT mRNA levels and MT concentrations on both d 6 and d 12 after injections. 4. It was concluded that the injected Zn-Pro S was the least favourable for bone Zn utilisation of broilers. The pancreas Zn concentration and pancreas MT gene expressions might not be sensitive enough to detect differences in the tissue utilisation of injected Zn in broilers between organic and inorganic Zn sources or among organic Zn sources.

Detection of p53 gene mutation by using a novel biosensor based on localized surface plasmon resonance.

Few studies to date have reported on the development and application of a nanobiosensor based on localized surface plasmon resonance (LSPR) for detecting gene mutations. This study aimed to develop a novel LSPR biosensor used for detecting p53 mutation. Nanosphere lithography was used to fabricate the silver nanoparticles. The DNA probe was designed to recognize the target sequence and immobilized on the chip surface by a covalent-coupling method using amine-group ligands. Synthetic oligonucleotides or PCR products were amplified from genomic DNA taken from blood samples and hybridized with the immobilized probe. Wild-type and mutant p53 was detected by measuring shifts in peak of LSPR extinction spectra. The low detection limit of the sensor for target sequence was 10 nM, and detection occurred over a wide dynamic range (10 nM - 10 µM). Importantly, the differences in measuring signal between wild-type and mismatched p53 DNA was significant, allowing for this sensor to effectively discriminate against single base mutations. In conclusion, we developed a biosensor with potential as a rapid, label-free, sensitive, and low-cost method for detecting p53 mutation. Our results suggest that such an LSPR-based biosensor provides an attractive alternative for clinical detection of genetic mutation.

Reduced expression of myocardin and serum response factor in the cavernous tissue of diabetic rats.

This study aimed to investigate the expression of myocardin and serum response factor (SRF) in the cavernous tissue of diabetic rats. The experimental diabetes model was induced in 8-week-old male Sprague-Dawley rats (200-220 g) by a single administration of streptozotocin. Both the diabetes mellitus group (DM group, n = 20) and the control group (NDM group, n = 10) were injected with a low dose of apomorphine to allow for the measurement and comparison of the corresponding penile erections. Western blot and qRT-PCR were used to determine the protein and mRNA expression levels of myocardin and SRF. Erectile function was significantly decreased in the DM group compared with the control group (P < 0.001). The mRNA and protein expression levels of myocardin and SRF were reduced in the cavernous tissue of diabetic rats compared with the control group (P < 0.001). It is concluded that diabetes inhibits the mRNA and protein expression of both myocardin and SRF in the cavernous tissue. This could play a key role in the development of erectile dysfunction in diabetic rats.

Estimation of standardized phosphorus retention for corn, soybean meal, and corn-soybean meal diet in broilers.

Two experiments were conducted to estimate standardized phosphorus (P) retention (SPR) of corn, soybean meal (SBM), and corn-soybean meal (C-SBM) diet in broilers and verify the additivity of SPR for feed formulation of broilers. In total, ninety-six 22-d-old male broilers with similar BW were used in each experiment. After 3 d of acclimation, chicks were fasted for 24 h and then fed P-free, corn, SBM, or C-SBM diets, respectively for 4 h in experiment 1 or 72 h in experiment 2. In experiment 1, the results showed that the excreta collection time of 52 h (48 h after feed withdrawal) was adequate for the estimation of SPR. The basal endogenous P loss (EPL) of chicks fed the P-free diet was estimated to be 123±7 mg/52 h per bird. The values of SPR corrected by basal EPL were 37.6 and 50.5% for corn and SBM, respectively. The determined value of SPR of the C-SBM diet was very close (P>0.79) to the predicted summation of SPR from corn and SBM (44.4 vs. 43.5%). In experiment 2, the results showed that the excreta collection time of 96 h (24 h after feed withdrawal) was sufficient for the estimation of SPR. The basal EPL of chicks fed the P-free diet was estimated to be 85.4±4.0 mg/96 h per bird. The values of SPR corrected by basal EPL were 40.2 and 52.9% for corn and SBM, respectively. The determined value of SPR of the C-SBM diet was lower (P<0.001) than the predicted summation of SPR from corn and SBM (39.7 vs. 46.0%), which might be due to the effect of higher total P intake. The results from the current study demonstrated that the P-free diet could be used for measuring basal EPL in broilers and then estimating the SPR values of feedstuffs for broilers. However, the additivity of SPR in the diet formulation needs to be studied further.

Evaluation of the compositional and nutritional values of phytase transgenic corn to conventional corn in roosters.

Three experiments were conducted to evaluate the compositional and nutritional values of corn grains [phytase transgenic corn (PTC) and isogenic conventional corn (CC)] and compare the efficacy of corn-based phytase and extraneous microbial phytase for enhancing the utilization of phytate phosphorus (P) in single corn or corn-soybean mixed meals (corn:soybean = 2.5:1, wt:wt) fed to roosters. Following a 48-h fasting period, 16 roosters were given 50 g of each sample via crop intubation and excreta were collected for 48 h. Nitrogen-free and phosphorus-free diets were used to evaluate endogenous amino acid and endogenous P losses, respectively. Chemical composition was not different between PTC and CC, whereas the phytase content for PTC was greater than CC (8,047 vs. 37 FTU/kg of corn, DM basis; P < 0.001). No difference was observed in the TME and true amino acid availability values between the PTC and CC in roosters. The true P utilization for PTC was greater than CC (37.92 vs. 55.85%; P < 0.001), and CC and PTC contained 0.13 and 0.19% available P (AP, DM basis; P < 0.001), respectively. There was no difference in P utilization (72.76 vs. 70.23%; P > 0.05) between roosters fed PTC and extraneous microbial phytase in equivalent FTU/kg of diets. The results of this study indicated that the chemical composition, TME, and true amino acid availability in PTC are essentially equivalent to that in CC, and the true P utilization for roosters is higher in PTC than in CC. Corn expressing phytase is as efficacious as equivalent microbial phytase when supplemented in corn-soybean diets for chickens.

Effects of supplemental zinc source and level on growth performance, carcass traits, and meat quality of broilers.

The objective of this study was to investigate the effects of dietary supplemental Zn on growth performance, carcass traits, and meat quality of broilers. Dietary treatments included the corn-soybean meal-based diet (control) and the basal diet supplemented with 60, 120, or 180 mg of Zn/kg as ZnSO(4), Zn amino acid A, Zn proteinate B, or Zn proteinate A. The results showed that birds fed diets supplemented with Zn had higher ADFI, ADG, and percentage of eviscerated yield than birds fed the control diet. Supplemental Zn significantly increased the redness value in breast muscle and pH values in thigh muscle, decreased shear force in thigh muscle, and decreased drip loss in breast and thigh muscle. The DM and intramuscular fat contents of the breast muscle in broilers fed diets with supplemental Zn were higher than those of the control. Results from this study indicated that Zn could promote growth and improve production performance of broilers independent of Zn source.

Doping dependence of heat transport in the iron-arsenide superconductor Ba(Fe(1-x)Co(x))2As2: from isotropic to a strongly k-dependent gap structure.

The temperature and magnetic field dependence of the in-plane thermal conductivity kappa of the iron-arsenide superconductor Ba(Fe(1-x)Co(x))2As2 was measured down to T approximately 50 mK and up to H = 15 T as a function of Co concentration x in the range 0.048 < or = x < or = 0.114. At H = 0, a negligible residual linear term in kappa/T as T-->0 at all x shows that the superconducting gap has no nodes in the ab plane anywhere in the phase diagram. However, while the slow H dependence of kappa(H) at T-->0 in the underdoped regime is consistent with a superconducting gap that is large everywhere on the Fermi surface, the rapid increase in kappa(H) observed in the overdoped regime shows that the gap acquires a deep minimum somewhere on the Fermi surface. Outside the antiferromagnetic-orthorhombic phase, the superconducting gap structure has a strongly k-dependent amplitude.

Room-temperature ferromagnetism and the scaling relation between magnetization and average granule size in nanocrystalline Zn/ZnO core-shell structures prepared by sputtering.

Ferromagnetism is found in nanocrystalline Zn/ZnO core-shell structures prepared by sputtering pure Zn with subsequent oxidation. The saturation magnetization (M(S)) of the passivated ZnO shells increases with decrease in average particle size (d). The Curie temperature of the samples is above 400 degrees C. It is found that the ferromagnetism has a close relationship with point defects in ZnO shells. The maximum magnetization is estimated to be 28 emu cm(-3) (i.e. 0.14 mu(B) per unit cell) at 300 K, which is over three orders of magnitude larger than that of undoped ZnO nanoparticles or nanorods (10(-3)-10(-2) emu cm(-3)). More importantly, there is a scaling relation of M(s) alpha 1/d(n) (n = 5.20 +/- 0.20) for samples with d

Effects of zinc source and phytate on zinc absorption by in situ ligated intestinal loops of broilers.

Two experiments were conducted to investigate the effects of Zn source and phytate on Zn absorption in broilers. In experiment 1, eight different Zn sources, including ZnSO4, Zn Gly chelate, Zn Met chelate, and Zn amino acid C complex with the weak complex strength (Zn AA C), Zn protein B complex with the moderate complex strength (Zn Pro B), and zinc protein A complex with the strong complex strength (Zn Pro A), and the mixtures of ZnSO4 with either Gly or Met (Zn+Gly or Zn+Met, respectively) were used to study the effects of Zn sources on Zn absorption by in situ ligated intestinal loops of broilers. In experiment 2, 3×4 factorial arrangements of treatments involving 3 phytate levels and 4 Zn sources were used to investigate the effect of phytate on Zn absorption. Three molar ratios of phytate to Zn were 0, 2:1, and 10:1, respectively, and 4 Zn sources included ZnSO4, Zn AA C, Zn Pro B, and Zn Pro A, respectively. No differences (P>0.05) were found among the absorption percentages of Zn as Zn+Gly, Zn+Met, and ZnSO4 in 3 intestinal segments. The absorption percentages of Zn as Zn Gly chelate, Zn Met chelate, Zn AA C, Zn Pro B, and Zn Pro A in the duodenum and jejunum were 29 to 129% higher (P<0.05) than those of Zn as ZnSO4, Zn+Gly, and Zn+Met in the following order: Zn Pro A>Zn Pro B>Zn AA C>Zn Gly chelate or Zn Met chelate>ZnSO4, Zn+Met, or Zn+Gly. The changes of Zn absorption as different Zn sources in the ileum were also observed and were similar to those in the duodenum and jejunum. There was a significant interaction (P<0.05) between phytate levels and Zn sources on Zn absorption in 3 intestinal segments. The absorption percentage of Zn as ZnSO4 in the duodenum with a phytate-added group (10:1) was 40% (P<0.05) lower than that of Zn as ZnSO4 without a phytate-added group. With the increasing phytate levels, the changes of Zn absorption as organic Zn sources in 3 intestinal segments were similar to those of ZnSO4 in the duodenum. However, the reduction of Zn absorption as organic Zn sources was lessened with the increasing complex strengths, and the highest absorption of Zn as Zn Pro A was observed. These results indicated that the absorption of Zn as organic Zn was more effective than that of Zn as inorganic Zn. The organic Zn absorption increased with the increasing complex strengths as well. The simple mixture of ZnSO4 with amino acid did not increase Zn absorption. In addition, the phytate could reduce Zn absorption as different Zn sources in 3 intestinal segments. Organic Zn sources could lessen the negative effect of phytate on Zn absorption, and then the absorption of organic Zn, especially Zn Pro A with strong complex strength, was more effective than inorganic Zn under the high levels of phytate.

Effects of age and strain on the expression of leptin receptor, neuropeptide Y and pro-opiomelanocortin in the hypothalamus of young chickens.

1. An experiment was conducted to study changes in the expression of the hypothalamic leptin receptor, neuropeptide Y (NPY) and proopiomelanocortin (POMC) with age during the early neonatal period in two different strains of chickens: Beijing-You (BY) and Arbor Acres (AA). 2. Compared with BY chickens, AA chickens ate more, and grew faster. Hypothalamic NPY concentrations of both strains increased with age until d 7 followed by a decline. Hypothalamic NPY of BY chickens on d 7 was lower than in AA chickens at the same age. 3. No difference with age was observed in hypothalamic α-melanocyte-stimulating hormone (α-MSH) of BY chickens, while hypothalamic α-MSH in AA chickens on d 0 was higher than on the other days. Compared with AA chickens, BY chickens showed lower hypothalamic α-MSH on d 0. 4. Similar developmental changes between two strains were observed in the expression of leptin receptor, NPY or POMC genes in the hypothalamus. Hypothalamic mRNA of leptin receptor on d 0 was higher than on d 1 and 7. Unlike NPY, hypothalamic NPY mRNA on d 0 was higher than on the other days. 5. Hypothalamic POMC mRNA decreased gradually with age until 7 d followed by a slight increase. 6. The results showed that the developmental changes of hypothalamic signal molecules varied with age and strain. NPY, α-MSH and leptin receptor might be involved in the early programming of feed intake in newly hatched chickens.