alpha-MSH enhances activity-based anorexia

Activity-based anorexia (ABA) is considered an animal model of anorexia nervosa (AN). In ABA, scheduled feeding in combination with voluntary access to running wheels, results in hyperactivity, hypophagia, body weight loss and activation of the HPA axis. Since stimulation of the melanocortin (MC) system has similar effects, this system is a candidate system involved in ABA. Here it is shown that chronic alpha-MSH treatment enhances ABA by increasing running wheel activity (RWA), decreasing food intake and increasing HPA axis activation.     

Circadian rhythmicity in substance use disorder male patients with and without comorbid depression under ambulatory and therapeutic community treatment

Although there have been described alterations of circadian rhythmicity both in patients with substance use disorder (SUD) and patients with major depressive disorder (MDD), the circadian characteristics of SUD patients with comorbid MDD (SUD-MDD) are unknown. Likewise, the possible influence of the different modalities of treatments (ambulatory or therapeutic community) upon the circadian rhythmicity of SUD patients has not been characterized. Therefore, this study analyzes the circadian rhythmic profiles of SUD and SUD-MDD patients under ambulatory and therapeutic community treatment. The sample was composed of 40 SUD and 40 SUD-MDD men, aged 22–55 yrs, under treatment and with abstinence for at least three months (including each group 20 ambulatory and 20 from therapeutic community). Patients completed a sociodemographic, clinical and sleep-wake schedules interview, the Composite Scale of Morningness, and wore on the wrist an ambulatory device known as iButton® Thermochron DS1921H, which registered their distal skin temperature every two minutes for 48 hours. All the groups showed a tendency to morningness without differences among them in concordance with their sleep-wake schedules. With regard to distal skin temperature circadian rhythm, SUD patients showed higher values than SUD-MDD in amplitude, relative amplitude, percentage rhythm, and first harmonic power, and lower minimum temperature in 10 consecutive hours (p < .043, in all cases). Therapeutic community group values were lower in minimum temperature and higher in amplitude, relative amplitude, and 12 harmonic accumulated power (p < .028, in all cases) as compared to ambulatory ones. Moreover, all groups showed higher Rayleigh vector and rhythm stability as compared to normative population (p < .043, in both cases). The circadian rhythmic differences observed for diagnosis and type of treatment are indicative of a higher circadian rhythmicity robustness in SUD and therapeutic community patients as compared to SUD-MDD and ambulatory ones, respectively. Although drug consumption exerts a negative effect on the circadian rhythmicity, our results (high amplitude and rhythm stability) are indicative of an adequate circadian functioning as well as of an adjustment to the light-dark cycle in both diagnosis and type of treatment which may constitute a marker of the adherence to treatment and recovery status.     

The historical biogeography of the southern group of the sucker genus Moxostoma (Teleostei: Catostomidae) and the colonization of central Mexico

The historical biogeography of the southern group of Moxostoma Rafinesque, 1820, a genus of Nearctic freshwater fishes belonging to the Catostomidae, along its entire distribution in North America was inferred to: (1) determine the biogeographical events responsible for its current pattern of diversity and distribution; (2) correlate the climatic and geologic history of the region with the biogeographical pattern observed; and (3) trace the colonization route into central Mexico and the western Pacific slope drainages. The sequences of mitochondrial cytochrome b and the third intron of the growth hormone were obtained for the members of the southern group and related species of the Catostomidae. Phylogenetic analyses and relaxed molecular clock analyses were performed to determine the relatedness of the species and to estimate divergence times. To uncover biogeographical patterns, a dispersal–extinction–cladogenesis (DEC) analysis was conducted. The phylogenetic analyses were consistent with the historical hydrographic scenario in the region. The divergence times show that the southern group evolved during the Pliocene–Pleistocene. The DEC analyses showed that vicariance and dispersal played an important role in the current distribution patterns of the lineages in central Mexico, and allow us to trace an independent route of colonization from the northern areas of North America into central Mexico.     

Sleep habits,circadian preferences and substance use in a Mexican population: the use of the Morningness-Eveningness-Stability-Scale improved (MESSi)

ABSTRACT

This study aimed to validate the Morningness-Eveningness-Stability-Scale improved (MESSi) in Mexico, analyzing the factor structure and sleep habits, combined with the proposal of cutoff values for the scales, and to assess the relationship with substance use. We applied the questionnaires through an online survey to a total sample of 510 Mexicans, aged 18–77 years (M = 27.79, SD = 10.24). The MESSi showed an acceptable fit and the Cronbach’s alpha coefficients were good to satisfactory in the Mexican sample in every subscale: Morning Affect (MA, α = 0.90), Eveningness (EV, α = 0.88), Distinctness (DI, α = 0.80). In order to obtain a better interpretation of the MESSi subscales, we decided to propose cutoff points corresponding to the 25th–75th percentile. The categories were depicted as strong trait presence, intermediate trait presence and weak trait presence. When applying the cutoff points for the MESSi sub-scales, with Morning Affect (MA), strong-types went to bed and woke up earlier and had more sleep than weak-types during weekdays and weekends and reported less social jetlag. For Eveningness (EV), strong-types went to bed and woke up later than weak-types on weekdays and weekends. Also, strong-types had a shorter time in bed during weekdays but not on weekends and reported more social jetlag. Lastly, with Distinctness (DI), the results reported that those with a strong-type showed greater amplitude on weekdays and weekends. Furthermore, the MESSi scale found that evening people consumed more alcohol and tobacco. Our study supported the validity and reliability of the MESSi in a Mexican population and the relationship between eveningness and substance consumption. Furthermore, the proposed cutoff scores for the MESSi sub-scales add a novel approach for the measurement and interpretation of the scale.     

Cross-Tissue and Tissue-Specific eQTLs: Partitioning the Heritability of a Complex Trait

Top signals from genome-wide association studies (GWASs) of type 2 diabetes (T2D) are enriched with expression quantitative trait loci (eQTLs) identified in skeletal muscle and adipose tissue. We therefore hypothesized that such eQTLs might account for a disproportionate share of the heritability estimated from all SNPs interrogated through GWASs. To test this hypothesis, we applied linear mixed models to the Wellcome Trust Case Control Consortium (WTCCC) T2D data set and to data sets representing Mexican Americans from Starr County, TX, and Mexicans from Mexico City. We estimated the proportion of phenotypic variance attributable to the additive effect of all variants interrogated in these GWASs, as well as a much smaller set of variants identified as eQTLs in human adipose tissue, skeletal muscle, and lymphoblastoid cell lines. The narrow-sense heritability explained by all interrogated SNPs in each of these data sets was substantially greater than the heritability accounted for by genome-wide-significant SNPs (∼10%); GWAS SNPs explained over 50% of phenotypic variance in the WTCCC, Starr County, and Mexico City data sets. The estimate of heritability attributable to cross-tissue eQTLs was greater in the WTCCC data set and among lean Hispanics, whereas adipose eQTLs significantly explained heritability among Hispanics with a body mass index ≥ 30. These results support an important role for regulatory variants in the genetic component of T2D susceptibility, particularly for eQTLs that elicit effects across insulin-responsive peripheral tissues.     

Effect of exogenous DNA on bovine sperm functionality using the sperm mediated gene transfer (SMGT) technique

Sperm mediated gene transfer (SMGT) could provide the opportunity to carry out transgenesis on a mass scale using spermatozoa as vectors for exogenous DNA. However, the efficiency of sperm‐mediated DNA transfer is still questionable, and the mode of transmission to the egg has not yet been well understood. Our aim was to investigate the capacity of bovine spermatozoa to carry exogenous DNA and its relationship to sperm functionality. We studied these parameters using flow cytometry to measure viability (necrosis and apoptosis) and capacitation status, computer‐assisted semen analysis (CASA) to measure motility parameters and in vitro fertilization (IVF) to assess fertilizing capacity. Furthermore, we studied the effect of capacitation status on interaction with exogenous DNA, and the role of heparin supplementation in this process. Bull spermatozoa showed a high capacity to bind DNA quickly and reached a maximum after 30 min, with approximately half of the DNA‐bound spermatozoa being viable. Incubation with exogenous DNA induced a decrease in sperm viability and motility and increased the proportion of apoptotic cells, but did not affect the cleavage rate in IVF assay. Heparin increased high‐lipid disorder and the number of sperm with DNA bound (viable and dead). In conclusion, this study shows that live spermatozoa can bind exogenous DNA with a slight negative effect in some parameters of sperm function that in our opinion, would not drastically compromise fertility. Mol. Reprod. Dev. 77: 687–698, 2010. © 2010 Wiley‐Liss, Inc.