Fabricio Damián Cid

Imidacloprid (IMI) is a widely used neonicotinoid insecticide that presents potential risks to non‐target avian species. This study investigated the sublethal effects of IMI on the health of the eared dove ( Zenaida auriculata ), a common granivorous bird in South America. The objective was to characterize the impacts of subchronic oral exposure to IMI on behavioral, physiological, hematological, and biochemical parameters. Eighteen adult male doves ( n = 18) were randomly assigned to three groups: a control group receiving water orally, and two treatment groups receiving IMI dissolved in water at doses equivalent to 1/15th (low dose, LD, 3.93 mg/kg b.m.) and 1/5th (high dose, HD, 11.8 mg/kg b.m.) of the oral LD ₅₀ , administered daily by gavage for 21 days. Health biomarkers measured included water intake, body mass, somatic indices, hematological profiles, and plasma biochemical parameters. Results indicated a significant decrease in body mass in the HD group of doves exposed to IMI. In this group, only an increase in the heterophil/lymphocyte ratio was observed among the hematological parameters. Biochemical parameters showed decreased lactate dehydrogenase (LDH) and increased serum butyrylcholinesterase (BuChE) activities. These findings suggest that IMI, even at sublethal doses, can trigger physiological stress responses, generate metabolic alterations, and exert neurotoxic effects in eared doves. Exposure levels in this study were below those allowed for IMI‐treated seeds in Argentina, underscoring the environmental risks to wild birds. Application of sensitive health biomarkers underscores the need for further ecotoxicological research and regulatory measures to mitigate the environmental impact of neonicotinoids on birds.

Oil and gas extraction, refining, reforming and transport are important production activities mainly conducted in the Southern Patagonia region of Argentina. Several threats to natural ecosystems have been associated with this industry, most of them related to the increase in toxic metals and metalloids in the environment and biota. Birds of prey are widely used to assess metals and metalloids pollution in the environment. This study determined levels of selected trace elements including both essential and toxic metals in the blood of Crested Caracara (Caracara plancus) nestlings and evaluated relationships between the trace elements composition levels and the distance between nests and oil production plants and the prevailing wind in Southern Patagonia, Argentina. Pb, As, Zn, Se, Ni, Cu, Cr, Cd and V were determined by inductively coupled plasma-mass spectrometry. Two groups of trace elements were correlated according to the blood levels detected (As-V-Cr; Zn-V-Cr), suggesting a common source of exposure to these trace elements. The prevailing wind constituted a promising mechanism to explain an association between the oil pipe-derived trace elements and the exposure of nestlings. Nestlings showed elevated levels of As, Se, Cd, Ni and Zn, which were higher than reference levels reported for other raptor populations. These results indicate that nestling Crested Caracaras are exposed to toxic trace elements in Southern Patagonia. This is the first report of trace elements in the blood of Crested Caracara nestlings inhabiting Southern Continental Patagonia, Argentina, and provides baseline data of this contamination in this species.

Lead (Pb) is a prevalent toxic metal in contaminated ecosystems, posing a real threat to living organisms. Although birds are highly sensitive to Pb, there is little information on its impact on the avian digestive system. This study was designed to compare the effects of chronic Pb exposure (for 15 and 30 days) on the activities of digestive enzymes—aminopeptidase-N (APN), maltase-glucoamylase (MG), and sucrase-isomaltase (SI)—between eared doves (Zenaida auriculata) and house sparrows (Passer domesticus). Our results showed that Pb-exposed sparrows exhibited inhibited digestive enzyme activities compared to the control, while treated doves did not show significant changes in enzyme activity. This difference in sensitivity between sparrows and doves may be due to physiological differences and water consumption. In conclusion, this study provides the first evidence of inhibited APN, MG, and SI activity in sparrows as a result of chronic Pb exposure through drinking water. Furthermore, our work contributes to the understanding of Pb toxicology in the digestive system of birds and its effect on the acquisition of energy, which should be considered when evaluating the impact of environmental pollutants on wildlife.

Lead (Pb) is a metal that can produces irreversible damage in living organisms. Some studies had reported that Pb produces histophysiological alterations in the digestive system (mainly liver) of birds; however, the effect of this metal on small intestine has not been fully examined. Additionally, little information is available on Pb disturbances in native birds of South America. The present study aimed to evaluate the effect of different Pb exposure times on blood δ-aminolevulinic acid dehydratase (δ-ALAD) activity and on the histological and morphometric characteristics of the digestive system (liver and proximal intestine) of eared doves (Zenaida auriculata). A decrease of the blood δ-ALAD activity, dilatation of blood vessels and leukocyte infiltrates in intestinal submucosa and muscular layers, and reduction of the enterocyte nuclear diameter and Lieberkühn crypts area were observed. In liver were noted steatosis, proliferation of bile ducts, dilated sinusoids, leukocyte infiltrates, and melanomacrophage centers. The portal tract area and the thickness of the portal vein wall were increased. In conclusion, the results showed that Pb produces histological and morphometric alterations on the liver and small intestine according to the exposure time, which should be considered when the dangerousness of environmental pollutants is evaluated in wild animals.

Fluctuations in food supply are frequent in nature during seasons, in different stages of annual cycle of animals, and lately, climate change has become a strong driving force that could affect food supply. An animal's capacity to resist fasting is, therefore, determined by its ability to store energy and control its allocation during periods of food restriction. Daily variations of metabolic substrates and their fluctuations during fasting are relevant to understand the acclimation to fasting. Since fasting is an ecological stressor, we investigated the daily variation of corticosterone levels in feeding and fasting in House Sparrows (Passer domesticus (Linnaeus, 1758)), and its short-term effect on some biochemical parameters. We found daily variations in body mass, glucose, triglycerides, plasma total protein, uric acid, and corticosterone. However, we did not find diurnal variations of hematocrit and the heterophil:lymphocyte ratio (HL ratio). Moreover, we did not find sex-related differences in any parameter. Throughout fasting, we found variations of glucose, triglycerides, total protein, uric acid, HL ratio, and corticosterone. During the photophase, biochemical and physiological responses to food deprivation contributed to the efficient use of resources in this small bird. In the course of fasting period, corticosterone could be responsible for alterations of some blood parameters such as glucose.

The profile of volatile compounds from the aerial parts of Eupatorium buniifolium was assessed by capturing the aroma of fresh plants using three commercial SPME phases. These headspace solid phase microextraction procedures (HS-SPME) were coupled to GC-FID and GC-MS analysis. Hydrocarbon sesquiterpenes were the main components of E. buniifolium volatiles, followed by hydrocarbon monoterpenes. The three fiber performances were statistically comparable in the extraction of both terpene groups. E. buniifolium essential oil (EO) was obtained by steam distillation (SD) and assessed by both, direct injection and HS-SPME. The three fibers could reliably adsorb/absorb the aromas of E. buniifolium EOs, with comparable with EO composition. The fresh plant volatile profile significantly differed from its EO because some sesquiterpene fraction remained in the biomass after SD. Extracts of the fresh plant material were obtained using organic solvents and evaluated by direct injection. Ethanol and ethyl acetate extracts gave a different aroma profile of E. bunnifolium than the EO.

It is widely known that intestinal capacities such as the enzymatic hydrolysis of carbohydrates, lipids and proteins, and the subsequent absorption of the hydrolyzed products, are evolutionary matched to dietary loads and feeding behaviors. In this study, we demonstrate that the protein expression of apically located sodium-dependent glucose cotransporter-1 (SGLT-1) throughout rat ontogeny is daily adjusted to afford glucose uptake when the load of this metabolically essential monosaccharide in the intestinal lumen is maximum. The jejunal expression of SGLT-1 protein in 14 one-day-old suckling pups was found to increase at dark and early light phase (P < 0.05), when they have a better access to mother milk. In weaning 21-d-old and juvenile 28-d-old rats, the cotransporter expression was high throughout the entire day (P < 0.05). Finally, adult 90-d-old rats showed a well-developed circadian rhythm for SGLT-1 protein (P < 0.05), whose expression increased at late light and dark phase when the highest intestinal glucose load was achieved. To our knowledge, these results are the first reporting the daily profile of SGLT-1 expression during rat early developmental stage and may contribute to understand the biological significance of a well-established molecular capacity to deal with the crucial increase of glucose load in the diet during the weaning process.

The acid mine drainage that originates in the abandoned gold mine in San Luis, Argentina, is released into La Carolina stream. The aim of this study was to determine the influence of this mine drainage on the physicochemical parameters of the area studied and on both prokaryotic and eukaryotic community structure. In addition, specific relationships between microbial taxonomic groups and physicochemical parameters were established. The drainage that flows into La Carolina stream acidifies the stream and increases its sulfate, Zn, Cd and Te concentrations. Microbial analysis showed that prokaryotic community structure is mainly affected by pH values. Actinobacteria and Gammaproteobacteria were abundant in samples characterized by low pH values, while Nitrospirae, Chloroflexi, Deltaproteobacteria, Thaumarchaeota and Euryarchaeota were associated with high concentrations of heavy metals. Otherwise, Alphaproteobacteria was present in samples taken in sunlit areas. Regarding eukaryotic community structure, the sunlight had the greatest impact. Inside the mine, in the absence of light, fungi and protists members were the most abundant microorganisms, while those samples taken in the presence of light displayed algae (green algae and diatoms) as the most abundant ones. After receiving the mine drainage, the stream showed a decrease in the diatom abundance and green algae predominated.

Summary: Many species show diet‐induced flexibility of activity of intestinal enzymes; however, molecular and genetic mechanisms responsible for such modulation are less known, particularly in altricial birds. The goal of our study was to test whether a diet‐induced increase in activity of intestinal maltase and sucrase in house sparrow nestlings is matched with an increase in maltase–glucoamylase (MG) and sucrase–isomaltase (SI) complex mRNAs respectively. Both enzyme activities were significantly higher in mid‐intestine of nestlings fed a medium‐starch (MS) diet compared to those fed a starch‐free (SF) diet. In contrast to the similar pattern of dietary induction for both enzyme activities, diet MS elevated significantly only the level of MG mRNA, but not SI mRNA. The coordinated increase in activity of maltase and in MG mRNA is consistent with the hypothesis that dietary induction of this enzyme is under transcriptional control. In contrast, the lack of such coordination for changes in activity of sucrase and SI mRNA suggests that upregulation of this enzyme may be achieved by post‐translational factor(s). We conclude that genetic mechanisms responsible for diet‐induced flexibility of digestive enzymes in birds may differ from that observed in mammals.