Antioxidant and Antimutagenic Activities of Mexican Oregano (Lippia graveolens Kunth)

Free essential oil methanolic extracts from three different geographical populations of Lippia graveolens in México were screened for antioxidant and antimutagenic properties by the DPPH and Kado microsuspension assay, respectively. Total phenolic and flavonoid contents as well as HPLC identification and quantification of naringenin and rosmarinic acid were also carried out. In addition, a taxonomical phenetic analysis was performed. The L. graveolens extracts showed varying content of phenols and flavonoids. Significant concentration of rosmarinic acid was found for the first time in the species. All the extracts were capable of scavenging DPPH radicals in a concentration dependent fashion; the IC₅₀ values correlate with the phenolic content. None of the extracts was toxic to TA100 and TA98 strains at the concentrations tested; moreover, the extracts at a concentration equivalent to 200 μg of gallic acid inhibited a 39 and 30% the mutagenicity induced by 4-nitro-o-phenylenediamine and sodium azide, respectively. The results suggest that the Mexican oregano is a source of polar bioactive ingredients for the food industry.     

Effect of nixtamalization on morphological and rheological characteristics of maize starch

Nixtamalization of maize grain is an ancient process that until now is used for tortilla production. This thermal-alkaline process produces important changes in morphology and rheological characteristics of starch that is the major component of maize. The aim of this study was to evaluate changes in the morphological and rheological properties of starch brought by nixtamalization of maize using image analysis and dynamic rheometry, respectively. Nixtamalized maize starch (NS) presented granule sizes higher than starch isolated from raw maize (S) due to the partial swelling produced in the nixtamalization process. In dynamic tests during the retrogradation kinetics, an inverse effect of the temperature was observed in the re-arrangement of starch components. NS was affected due to the thermal-alkaline process presenting an annealing that provoked a reduction in its ability to develop gels. This information is important during the processing of nixtamalized maize to masa and tortilla production.     

Evidence for a relationship between bovine erythrocyte lipid membrane peculiarities and immune pressure from ruminal ciliates

Erythrocytes of bovines and other ruminants have a strikingly anomalous phospholipid composition, with low or absent phosphatidylcholine (PC) together with high sphingomyelin (SM) content. Here, we report the presence in normal bovine serum of high levels of anti-phospholipid antibodies of IgM isotype against, PC and the phosphono analogue of phosphatidylethanolamine, aminoethylphosphonolipid (AEPL), normally produced by rumen ciliates. In contrast, no antibodies were detected against SM or N-acyl-phosphatidylethanolamine (NAPE), the major components of bovine erythrocytes. In addition, we found that exposure of the ciliate Tetrahymena thermophila to bovine serum results in rapid lysis, an effect that was inhibited by adsorption of the serum with SM/AEPL liposomes. Furthermore, incubation with bovine serum had a similar effect on freshly obtained ruminal ciliates, and the lytic activity was eliminated by pre-adsorption of the serum with SM/PE liposomes. The ruminant mode of life with its concomitant ciliate fauna is hereby linked to the peculiar conformation of bovine erythrocyte membranes. We propose that the unique phospholipid composition of bovine erythrocytes appears as an evolutionary adaptation to tolerate the lytic effects of anti-phospholipid antibodies generated against AEPL, a membrane component of the huge mass of ruminal ciliates, necessary commensals of this group of mammals.     

Reproductive outcomes of anestrous goats supplemented with spineless Opuntia megacantha Salm-Dyck protein-enriched cladodes and exposed to the male effect

Tropical Animal Health and Production - The possible influence of the “male effect” upon reproductive outcomes of adult anestrous goats under marginal rangeland conditions and...     

Genetic parameters for nitrogen fractions content in Mexican Brown Swiss cattle milk

Tropical Animal Health and Production - Nitrogen plays an important role in the metabolism of living organisms due to the variety of physiological functions that involve molecules that contain it....     

Recent advances in bovine sperm cryopreservation techniques with a focus on sperm post‐thaw quality optimization

Sperm cryopreservation facilitates the storage and transport of germplasm for its use in artificial insemination (AI) and other advanced reproductive technologies. The cryopreservation process can damage sperm and compromise functionality. Several cryobiological studies have found that the physical and biological factors that affect sperm survival at low temperatures during the cryopreservation process often involve the integrity of sperm membrane. In this review, the behaviour of the sperm membrane against cooling, cold shock, ice crystal formation, oxidative stress, osmotic changes, reorganization of the lipid bilayer and addition of cryoprotective agents (CPA) is discussed. In addition, the phenomenon of reactive oxygen species (ROS) and its relationship with the cryopreservation process is also described. Semen cryopreservation techniques have progressed slowly in past years, and the current performance, measured as post‐thawed survival, is not very different compared to past decades. Recent advances in understanding the structure of the cell membrane, its function and metabolism have driven to new conservation systems, including lyophilization and vitrification. However, none of these technologies is commercially available, although its future appears very promising.     

Edge Effect on Acorn Removal and Oak Seedling Survival in Mexican Lower Montane Forest Fragments

Vegetation structure of forest edges and type of adjacent field can affect seed and seedling survival patterns of tree species. We investigated acorn removal and seedling survival of Quercus germana and Q. xalapensis in relation to woody plant density across old field-forest gradients with soft and abrupt edges. Experiments were established along four parallel bands located at 40–50 m in the forest, forest and field edges (0–10 m to each side of the border), and 20–30 m in the old field. Within each band, woody plant and acorn density was measured, and four points for acorn and seedling removal experiments were randomly positioned. In each position, 20 acorns or four seedlings were placed. Survival was monitored during one month. In abrupt edges, acorn density was higher along edges than in forest interior. Also, higher acorn removal and seedling mortality were observed in the adjacent old-field whereas acorn and seedling survival was the highest at the edges. Acorn and seedling survival was positively correlated to woody vegetation density. As the vegetation density of field and forest edges grows, abrupt edges develop into soft edges, and they become more hospitable to oak recruitment and then to forest cover expansion.     

Gross Morphology of Diseased Tissues in Nezara viridula (Hemiptera: Pentatomidae) and Molecular Characterization of an Associated Microsporidian

Nezara viridula (L.) (Hemiptera: Pentatomidae), commonly known in the U.S. as the southern green stink bug (SGSB), is a cosmopolitan, highly polyphagous feeder that causes severe damage to a wide range of agronomically important crops such as fruit, vegetable, grain, tobacco, and cotton, throughout much of the United States, and is a global pest of considerable ecological, agricultural, and economical interest. During dissection of female Nz. viridula, conspicuous black and brown spots or lesions were observed on various internal organs. To determine the cause of these spots or lesions, tissues of fat body, spermatheca, ovaries, and ovulated eggs were collected from healthy and infected individuals. The gross morphology of the spots was characterized, and the microorganisms associated with the infection were identified by amplicon sequencing of the V4 region of the small subunit rRNA gene. The presence of a microsporidian pathogen Nosema maddoxi, Becnel, Solter, Hajek, Huang, Sanscrainte, & Estep (Microsporidia: Nosematidae) which has been observed on other species of stink bug, was evidenced for the first time. The characterization of the gross morphology of this associated microsporidian may enable more rapid determination of microsporidia infection in stink bug colonies and field populations.     

Haematological and histological findings in birds experimentally infected with highly pathogenic H5N2 avian influenza virus

Experimental infection of specific-pathogen-free (SPF) Leghorn chickens with a highly pathogenic H5N2 avian influenza virus produced cellular hyperplasia in the bone marrow at 36 hours post infection (hpi) and haematological evidence of monocytosis, thrombocytopenia and heterophilia was also detected. An early, significant and progressive haematological change was thrombocytopenia starting at 24 hpi without an increase of prothrombin time. The findings suggest that highly pathogenic avian influenza virus interferes only with the primary haemostatic mechanisms by consumption of thrombocytes, while the secondary haemostatic mechanisms remain intact.