67 research outputs found
Face Your Fears: Cleaning Gobies Inspect Predators despite Being Stressed by Them
Social stressors typically elicit two distinct behavioural responses in vertebrates: an active response (i.e., “fight or flight”) or behavioural inhibition (i.e., freezing). Here, we report an interesting exception to this dichotomy in a Caribbean cleaner fish, which interacts with a wide variety of reef fish clients, including predatory species. Cleaning gobies appraise predatory clients as potential threat and become stressed in their presence, as evidenced by their higher cortisol levels when exposed to predatory rather than to non-predatory clients. Nevertheless, cleaning gobies neither flee nor freeze in response to dangerous clients but instead approach predators faster (both in captivity and in the wild), and interact longer with these clients than with non-predatory clients (in the wild). We hypothesise that cleaners interrupt the potentially harmful physiological consequences elicited by predatory clients by becoming increasingly proactive and by reducing the time elapsed between client approach and the start of the interaction process. The activation of a stress response may therefore also be responsible for the longer cleaning service provided by these cleaners to predatory clients in the wild. Future experimental studies may reveal similar patterns in other social vertebrate species when, for instance, individuals approach an opponent for reconciliation after a conflict
Overview of phlorotannins’ constituents in Fucales
Fucales are an order within the Phaeophyceae that include most of the common littoral seaweeds in temperate and subtropical coastal regions. Many species of this order have long been a part of human culture with applications as food, feedand remedies in folk medicine. Apart from their high nutritional value, these seaweeds are also a well-known reservoir of multiple bioactive compounds with great industrial interest. Among them, phlorotannins, a unique and diverse class of brown algae-exclusive phenolics, have gathered much attention during the last few years due to their numerous potential health benefits. However, due to their complex structural features, combined with the scarcity of standards, it poses a great challenge to the identification and characterization of these compounds, at least with the technology currently available. Nevertheless, much effort has been taken towards the elucidation of the structural features of phlorotannins, which have resulted in relevant insights into the chemistry of these compounds. In this context, this review addresses the major contributions and technological advances in the field of phlorotannins extraction and characterization, with a particular focus on Fucales.This work received financial support from PT national funds (FCT/MCTES, Fundação
para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through
the projects UIDB/50006/2020 and UIDP/50006/2020. Thanks to PTDC/BAA-AGR/31015/2017,
“Algaphlor—Brown algae phlorotannins: From bioavailability to the development of new functional
foods”, co-financed by the Operational Programme for Competitiveness and Internationalization—
POCI, within the European Regional Development Fund (FEDER), and the Science and Technology
Foundation (FCT), through national funds. Silva S. thanks FCT for funding through program DL
57/2016–Norma transitória (Ref. SFRH/BPD/74299/2010)
Mitochondrial Preconditioning: A Potential Neuroprotective Strategy
Mitochondria have long been known as the powerhouse of the cell. However, these organelles are also pivotal players in neuronal cell death. Mitochondrial dysfunction is a prominent feature of chronic brain disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD), and cerebral ischemic stroke. Data derived from morphologic, biochemical, and molecular genetic studies indicate that mitochondria constitute a convergence point for neurodegeneration. Conversely, mitochondria have also been implicated in the neuroprotective signaling processes of preconditioning. Despite the precise molecular mechanisms underlying preconditioning-induced brain tolerance are still unclear, mitochondrial reactive oxygen species generation and mitochondrial ATP-sensitive potassium channels activation have been shown to be involved in the preconditioning phenomenon. This review intends to discuss how mitochondrial malfunction contributes to the onset and progression of cerebral ischemic stroke and AD and PD, two major neurodegenerative disorders. The role of mitochondrial mechanisms involved in the preconditioning-mediated neuroprotective events will be also discussed. Mitochondrial targeted preconditioning may represent a promising therapeutic weapon to fight neurodegeneration
Indo-Pacific parrotfish exert partner choice in interactions cleanerfish but Caribbean parrotfish do not
Cooperation theory puts a strong emphasis on partner control mechanisms that have evolved to stabilize cooperation against the temptation of cheating. The marine cleaning mutualism between the Indo-Pacific bluestreack cleaner wrasse, Labroides dimidiatus, and its reef fish ‘clients’ has been a model system to study partner control mechanisms and counterstrategies. These cleaners cooperate by eating ectoparasites; however, they can cheat by taking client mucus, which they prefer. Such a conflict may be the exception. For example, Caribbean cleaning gobies, Elacatinus spp., prefer to eat ectoparasites instead of mucus. While partner control mechanisms and counterstrategies seem to be absent in cleaning gobies, no study has directly compared cleaner wrasses and cleaning gobies by using the same methods. We examined systematic differences in cleaning interaction patterns and strategic behaviour exhibited by 12 closely related parrotfish species in the two systems. Parrotfish seeking cleaner wrasses visited them
more often and spent more time with their cleaner than parrotfish seeking cleaning gobies. Moreover, the clients of cleaner wrasses returned more often to the same cleaner following a positive interaction,
whereas the clients of cleaning gobies were less influenced by the outcome of previous interactions. We hypothesize that the higher frequency and repeated nature of interactions observed in the cleaner
wrasse system, combined with the need to resolve conflicts, might have been prerequisites for the development of complex behavioural strategies
Brain levels of nonapeptides in four labrid fish species with different levels of mutualistic behavior
a b s t r a c t There is strong evidence that brain nonapeptides are implicated as modulators of a wide array of social and reproductive behaviors in fishes. However, the question remains, as to whether there is a link between the distribution of active nonapeptides across brain regions and fishes specific behavioral phenotypes. To explore this link we compared the nonapeptides' profile across the brains of fishes representing different degrees of mutualistic behavior (here: cleaning behavior). Herein we studied the quantitative distribution of both nonapeptides, arginine vasotocin (AVT) and isotocin (IT), in the brains of four species of fish belonging to the family Labridae: two are obligatory cleaners throughout their entire life (Labroides dimidiatus and Labroides bicolor), one species is a facultative cleaner (Labropsis australis; juveniles are cleaners and adults are corallivorous), and one is a non-cleaner species, corallivorous throughout its entire life (Labrichthys unilineatus). The biologically available AVT and IT concentrations were measured simultaneously in distinct brain macro-areas: forebrain, optic tectum, cerebellum and brain stem, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We showed that the levels of both AVT and IT varied significantly across species, as measured in the whole brain or in the specific macro-areas. Significantly higher AVT concentrations in the cerebellum which were found in the obligate cleaners seemed to be related to expression of mutualistic behavior. On the other hand, the higher levels of brain IT in the non-cleaner L. unilineatus suggested that these might be linked to the development of sexual dimorphism, which occurs only in this non-cleaner species
A polyalanine peptide derived from polar fish with anti-infectious activities
Due to the growing concern about antibiotic-resistant microbial infections, increasing support has been given to new drug discovery programs. A promising alternative to counter bacterial infections includes the antimicrobial peptides (AMPs), which have emerged as model molecules for rational design strategies. Here we focused on the study of Pa-MAP 1.9, a rationally designed AMP derived from the polar fish Pleuronectes americanus. Pa-MAP 1.9 was active against Gram-negative planktonic bacteria and biofilms, without being cytotoxic to mammalian cells. By using AFM, leakage assays, CD spectroscopy and in silico tools, we found that Pa-MAP 1.9 may be acting both on intracellular targets and on the bacterial surface, also being more efficient at interacting with anionic LUVs mimicking Gram-negative bacterial surface, where this peptide adopts α-helical conformations, than cholesterol-enriched LUVs mimicking mammalian cells. Thus, as bacteria present varied physiological features that favor antibiotic-resistance, Pa-MAP 1.9 could be a promising candidate in the development of tools against infections caused by pathogenic bacteria.National Institute of Allergy and Infectious Diseases (U.S.) (R21AI098701
Human Paraoxonase Gene Polymorphisms and Coronary Artery Disease Risk
Introdução: As doenças complexas como a
doença das artérias coronárias (DAC), a
hipertensão e a diabetes, são usualmente
causadas pela susceptibilidade individual a
múltiplos genes, factores ambientais e pela
interacção entre eles. As enzimas da
paraoxonase humana (PON), particularmente a
PON1, têm sido implicadas na patogenia da
aterosclerose e da DAC. Dois polimorfismos
comuns na região codificante do gene, com
substituição Glutamina (Q) /Arginina (R) na
posição 192 e Leucina /Metionina na posição
55 influenciam a actividade da PON1. Vários
estudos têm investigado a associação entre os
polimorfismos da PON1 e a DAC, com
resultados contraditórios.
Objectivo: 1- Avaliar a associação dos
polimorfismos da PON1 com o risco de DAC.
2-Estudar a interacção destes polimorfismos
com outros situados em genes candidatos
diferentes, na susceptibilidade para o
aparecimento da DAC.
Material e Métodos: Estudámos em 298
doentes coronários e 298 controlos saudáveis,
através de um estudo caso/controlo, o risco de
DAC associado aos polimorfismos da PON1,
192Q/R e 55L/M. Numa segunda fase
avaliámos o risco das interacções polimórficas
PON1 192 RR + MTHFR 1298 AA; PON1
192 R/R + ECA DD; PON1 192 R/R + ECA 8
GG. Finalmente construímos um modelo de
regressão logística (no qual entraram todas as
variáveis genéticas, ambientais e bioquímicas,
que tinham mostrado significância estatística
na análise univariada), para determinar quais
as que se relacionavam de forma significativa e
independente com DAC.
Resultados: Verificámos que o genótipo PON155 MM tinha uma distribuição superior na
população doente mas não atingia significância
estatística como factor de risco para DAC. O
PON1 199 RR apresentou um risco relativo
80% superior relativamente à população que o
não possuía (p=0,04). A interacção da PON1
192 RR e da MTHFR 1298 AA, polimorfismos
sedeados em genes diferentes, apresentou um
risco relativo de DAC de 2,76
(OR=2,76;IC=1,20- 6,47; P=0,009), bastante
superior ao risco de cada polimorfismo isolado,
assim como a associação da PON1 RR + ECA
DD (com polimorfismos também sedeados em
genes diferentes), que apresentou um risco
337% superior relativamente aos que não
possuíam esta associação (OR=4,37;IC=1,47-
13,87; P=0,002). Da mesma forma a associação
entre a PON1 RR e ECA 8 GG, revelou um
risco ainda mais elevado (OR=6;23; IC=1,67-
27,37; P<0,001). Após modelo de Regressão
Logística as variáveis que ficaram na equação
representando factores de risco significativos e
independentes para DAC, foram os hábitos
tabágicos, doença familiar, diabetes,
fibrinogénio, Lp (a) e a associação PON1 192
RR + ECA 8 GG. Esta última associação
apresentou, na regressão logística, um
OR=14,113; p=0,018
Conclusões: O genótipo PON1 192 RR
apresentou, se avaliado isoladamente, um risco
relativo de DAC 80% superior relativamente à
população que não possuía este genótipo. A
associação deste polimorfismo com outros
polimorfismos sedeados em genes diferentes,
codificando para diferentes enzimas e
pertencendo a sistemas fisiopatológicos
distintos (MTHFR1298 AA, ECA DD e ECA 8
GG), aumentou sempre o risco de eclosão da
DAC. Após correcção para os outros factores
de risco clássicos e bioquímicos, a associação
PON1 192 RR + ECA 8 GG, continuou a ser
um factor de risco significativo e independente
para CAD.Background: Complex diseases such as
coronary artery disease (CAD), hypertension
and diabetes are usually caused by individual
susceptibility to multiple genes, environmental
factors, and the interaction between them. The
paraoxonase 1 (PON1) enzyme has been
implicated in the pathogenesis of
atherosclerosis and CAD. Two common
polymorphisms in the coding region of the
PON1 gene, which lead to a glutamine
(Q)/arginine (R) substitution at position 192
and a leucine (L)/methionine (M) substitution
at position 55, influence PON1 activity. Studies
have investigated the association between these
polymorphisms and CAD, but with conflicting
results.
Aims: 1) To evaluate the association between
PON1 polymorphisms and CAD risk; and 2) to
study the interaction between PON1
polymorphisms and others in different
candidate genes.
Methods: We evaluated the risk of CAD
associated with PON1 Q192R and L55M
polymorphisms in 298 CAD patients and 298
healthy individuals. We then evaluated the risk
associated with the interaction of the PON1
polymorphisms with ACE DD, ACE 8 GG and
MTHFR 1298AA. Finally, using a logistic
regression model, we evaluated which variables
(genetic, biochemical and environmental) were
linked significantly and independently with
CAD.
Results: We found that the PON1 55MM
genotype was more common in the CAD population, but this did not reach statistical
significance as a risk factor for CAD, while
PON1 192RR presented an 80% higher
relative risk compared to the population
without this polymorphism. The interaction
between PON1 192RR and MTHFR 1298AA,
sited in different genes, increased the risk for
CAD, compared with the polymorphisms in
isolation (OR=2.76; 95% CI=1.20-6.47;
p=0.009), as did the association of PON1
192RR with ACE DD, which presented a
337% higher risk compared to the population
without this polymorphic association
(OR=4.37; 95% CI=1.47-13.87; p=0.002).
Similarly, the association between PON1
192RR and ACE 8 GG was linked to an even
higher risk (OR=6.23; 95% CI=1.67-27.37;
p<0.001). After logistic regression, smoking,
family history, fibrinogen, diabetes, Lp(a) and
the association of PON1 192RR + ACE 8 GG
remained in the regression model and proved
to be significant and independent risk factors
for CAD. In the regression model the latter
association had OR=14.113; p=0.018.
Conclusion: When analyzed separately, the
PON1 192RR genotype presented a relative
risk for CAD 80% higher than in the
population without this genotype. Its
association with other genetic polymorphisms
sited in different genes, coding for different
enzymes and belonging to different
physiological systems, always increased the
risk for CAD. After correction for other
conventional and biochemical risk factors, the
PON1 192RR + ACE 8 GG association
remained a significant and independent risk
factor for CAD.info:eu-repo/semantics/publishedVersio
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