Dietary Flaxseed Oil Supplementation Mitigates the Effect of Lead on the Enzymes of Carbohydrate Metabolism, Brush Border Membrane, and Oxidative Stress in Rat Kidney Tissues

Lead is a heavy metal widely distributed in the environment. Lead is a ubiquitous environmental toxin that is capable of causing numerous acute and chronic illnesses. Human and animal exposure demonstrates that lead is nephrotoxic. However, attempts to reduce lead-induced nephrotoxicity were not found suitable for clinical use. Recently, flaxseed oil (FXO), a rich source of ω-3 fatty acids and lignans, has been shown to prevent/reduce the progression of certain types of cardiovascular and renal disorders. In view of this, the present study investigates the protective effect of FXO on lead acetate (PbAc)-induced renal damage. Rats were pre-fed normal diet and the diet rich in FXO for 14 days, and then, four doses of lead acetate (25 mg/kg body weight) were administered intraperitoneally while still on diet. Various serum parameters, enzymes of carbohydrate metabolism, brush border membrane (BBM), and oxidative stress were analyzed in rat kidney. PbAc nephrotoxicity was characterized by increased serum creatinine and blood urea nitrogen. PbAc increased the activities of lactate dehydrogenase and NADP-malic enzyme, whereas it decreased malate and glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, fructose-1, 6-bisphosphatase, and BBM enzyme activities. PbAc caused oxidant/antioxidant imbalances as reflected by increased lipid peroxidation and decreased activities of superoxide dismutase, glutathione peroxidase, and catalase. In contrast, FXO alone enhanced the enzyme activities of carbohydrate metabolism, BBM, and antioxidant defense system. FXO feeding to PbAc-treated rats markedly enhanced resistance to PbAc-elicited deleterious effects. In conclusion, dietary FXO supplementation ameliorated PbAc-induced specific metabolic alterations and oxidative damage by empowering antioxidant defense mechanism and improving BBM integrity and energy metabolism.     

"In vitro" study on release of cyclic AMP and thyroid hormone in autonomously functioning thyroid nodules

The TSH effect on slice and the incubation medium cyclic AMP levels and T3 and T4 released from 8 autonomously functioning thyroid nodules (AFTN) and their respective perinodular (PN) tissues were examined. The thyroid slices were incubated in Eagle's Medium containing TSH (5 to 100 mU/ml) for 60 min and 300 min for tissue cyclic AMP generation and for cyclic AMP, T3 and T4 release, respectively. Basal cyclic AMP levels were not different either in AFTN and in PN slices or into the incubation medium. In both tissues TSH produced a similar cyclic AMP generation. In contrast, cyclic AMP released into the incubation medium was significantly higher in AFTN than in PN tissues, after TSH stimulation. Basal T3 values and TSH-stimulated T3 release in AFTN were not different from PN tissue. However, basal T4 levels were significantly higher in AFTN than in PN tissue as well as T4 released in response to TSH. In addition, T3/T4 ratio was lower in AFTN than in PN tissues. The cyclic AMP released into the incubation medium correlated with both T3 and T4 release in PN tissue but in the AFTN tissue no correlations were found. These findings suggest that the adenylate cyclase-cyclic AMP system is more sensitive to TSH-stimulation in AFTN when compared with PN tissue and that AFTN tissue has a preferential T4 secretion.     

Glucocorticoid inhibition of immunoreactive beta-endorphin release from the anterior lobe of the rat pituitary: in vitro and in vivo studies

Glucocorticoid control of pituitary beta-endorphin (beta-END) release was investigated in vitro and in vivo. Cultured cells of both rat anterior (AL) and neurointermediate (NIL) lobe released beta-END-like immunoreactivity (beta-END-LI) in response to epinephrine (10(-7) M); however, only the response of AL cells was prevented by corticosterone (10(-8)-10(-6) M) or dexamethasone (10(-9)-10(-7) M). Gel chromatographic analysis (Sephadex G-50) revealed that the major forms of beta-END-LI released by AL cells corresponded to beta-END and beta-lipotropin (beta-LPH) in molecular size, whereas virtually all of the immunoreactivity released by NIL cells resembled beta-END. In vivo administration of dexamethasone attenuated the stress-induced release of beta-END-LI in a dose- and time-related fashion, having a more pronounced effect on plasma levels of beta-END-LI corresponding to beta-LPH in molecular size. Metyrapone (100 mg/kg), an inhibitor of glucocorticoid synthesis, evoked a rapid (20-40 min) four- to sixfold increase in total plasma beta-END-LI and 75% of this rise was due to immunoreactivity resembling beta-LPH in size. This response was diminished by coadministration of either dexamethasone (0.05-1.25 mg/kg) or corticosterone (0.05-1.25 mg/kg) and completely prevented by 4-hr pretreatment with dexamethasone (50 micrograms/kg). The briskness of the plasma beta-END-LI response to acute changes in glucocorticoid status suggests that a "rapid" feedback mechanism operates in the physiologic control of pituitary beta-END-LI secretion. Moreover, the ability of glucocorticoids to selectively inhibit AL release of beta-END-LI in vitro and their pronounced effect on plasma levels of beta-END-LI resembling beta-LPH, a marker of AL secretion, together indicate that glucocorticoids exert a selective influence over the secretion of AL corticotrophs in vivo. This demonstration of differential regulation of the AL versus IL secretion of beta-END-LI in vivo most likely reflects a phenomena having biologic importance related to the different physiologic actions of the several molecular forms of beta-END-LI secreted by the two tissues.     

Isolation and characterization of Y chromosome DNA probes.

A sorted, cloned Y chromosome phage library was screened for unique Y chromosome sequences. Of the thousands of plaques screened, 13 did not hybridize to radiolabeled 46,XX total chromosomal DNA. Three plaques were characterized further. Clone Y1 hybridized to multiple restriction enzyme fragments in both male and female DNA with more intense bands in male DNA. Clone Y2, also found in female and male DNA, is probably located in the pseudosutosomal region because extra copies of either the X or Y chromosomes increased Y2 restriction enzyme fragment intensity in total cellular DNA. Clone Y5 was male specific in three of four restriction enzyme digests although in the fourth a light hybridizing band was observed in both male and female DNA. Clone Y5 was sublocalized to band Yq 11.22 by hybridization to a panel of cellular DNA from patients with Y chromosome rearrangements. Clone Y5 can be used to test for retention of the proximally long arm Y suggested to cause gonadal cancer in carrier females. The long series of GA repeats in Y5, anticipated to be polymorphic, may provide a sensitive means to follow Y chromosome variation in human populations.     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.