Search

Floral nectar is the main reward offered to pollinators. The behaviour and efficacy of the pollinators themselves are affected by nectar traits, but the latter may vary within the same plant and even the same flower, depending on intrinsic and extrinsic factors (Schaeffer et al. 2016, Palmer‐Young et al. 2019). In this study, we investigated whether the nectar of Buglossoides purpurocaerulae (L.) I.M.Johnst. (Boraginaceae, Lithospermae) changed through functionally different floral stages and after insect visits.B. purpurocaerulea is a self‐incompatible plant relying on pollinators for its sexual reproduction. Flowers show incomplete proterogyny and no hercogamy, thus self‐pollination could potentially occur. The studied population is situated close to Bologna, in the protected area SIC‐ZPS IT4050001. Nectar samples were collected from different floral stages and from both bagged and unbagged flowers. HPLC analyses were performed to investigate amino acid and sugar composition.We found that nectar volume and sugar abundance are affected by floral phenology as well as by insect visitation. When visits are prevented, the older flowers contain more nectar but lower sugar concentration. These results suggest nectar sugar reabsorption in unvisited flowers. At the female stage, nectar shows a lower sugar content but as concentrated as in the other phenological stages. In contrast, the amino acid profile does not change during the flower lifespan, being relatively rich already in the bud. In particular, the high concentration of β‐alanine, which is likely to affect pollinator preference because of its involvement in functional flight muscles, possibly explains why the female stage is already attractive to insects (Bogo et al. 2019)

La quarta edizione di "Botanica sistematica: un approccio filogenetico" esce a 8 anni dalla terza, nell'intento di riportare i progressi compiuti in questa disciplina. "Le nostre classificazioni diventeranno, per quanto possibile, genealogie" affermava Darwin nel saggio sulle specie del 1859 e così è stato: la sistematica biologica, alla luce di un'impostazione evoluzionistica, e superando la staticità di una "scala naturae" di aristotelica memoria, si è sviluppata privilegiando una visione dinamica della diversità degli organismi viventi, cioè la concezione di un'evoluzione non più lineare, ma ramificata, che ha portato alla "consacrazione dell'albero quale immagine della natura", come Giulio Barsanti scrive in "Una lunga pazienza cieca. Storia dell'evoluzionismo". Questo volume si concentra sulla porzione del complesso albero della vita in cui si collocano le piante; focalizzandosi in particolare sulle piante a fiore, gli autori ne delineano le relazioni filogenetiche, riportandole in una classificazione che rifletta il possibile svolgimento della storia evolutiva degli organismi vegetali. Basata tradizionalmente su caratteri morfologici, la botanica sistematica nel tempo ha utilizzato informazioni provenienti da diverse fonti, purché in grado di evidenziare differenze e affinità entro e tra taxa; la classificazione proposta in questo volume è il risultato di analisi comparate di dati non solo morfologici, ma anche biochimici, ultrastrutturali, cariologici, molecolari. Questi ultimi, derivati soprattutto da sequenze nucleotidiche del DNA, si sono aggiunti negli ultimi decenni, permettendo di integrare approcci diversi. Gli alberi filogenetici che vengono proposti sono modellati sui principi rigorosi della cladistica; di conseguenza, da un punto di vista nomenclaturale, ricevono un riconoscimento tassonomico soltanto i gruppi che risultano strettamente monofiletici. Questo significa abbandonare, com'è noto, raggruppamenti tramandati dalla tradizione, come la confortevole dicotomia monocotiledoni/dicotiledoni, giunta fino a noi dai botanici inglesi del 17° secolo, e adeguarsi a raggruppamenti relativamente nuovi (i.e., il clade delle Streptofite, o quello delle Eufillofite) o nuovissimi (i.e., il clade SARP, che trascrivo come sigla, non avendo trovato una traduzione adeguata per "Diaphoretickes"). Quanto ciò possa agevolare la comunicazione tra esperti, o addirittura tra non esperti, che pure dovrebbe essere uno degli scopi della sistematica, è inutile dire. Per contro non si può dubitare sulla validità del metodo oggettivo e riproducibile, e quindi scientifico, adottato dalla cladistica nell'indagare il rapporto causa-effetto tra evoluzione e filogenesi. Lucia Conte

Floral and extrafloral angiosperms’ nectar is undoubtedly recognized as a valuable energetic alimentary resource for a large variety of animals. Through nectar consumption insects, small mammals, birds, marsupials and reptiles establish more or less specialized interactions with plants. But according to recent studies, nectar mediates interactions that are much more complex than simply alimentary relations. From the more abundant nectar compounds, i.e. sugars and amino acids mainly responsible for its high alimentary value, attention of scientists is moving towards compounds that are not directly connected with its alimentary importance. Among these, secondary compounds appear to have a special role in regulating interaction with other organisms. Although very few is known about their ecological roles in nectar, recently it was proved that secondary compounds may affect the nectar feeders’ behaviour interacting with their neurobiology. We addressed a special focus on one class of secondary compounds: the non-protein amino acids. Their presence in floral nectar has been reported since long time but their ecological function has not been investigated. Data from several phylogenetically unrelated species indicate that they may represent a consistent part of the total amino acid content of floral nectar (25-45%) and generally the more abundant ones are γ-amino butyric acid (GABA) and β-alanine. The study of nectar chemistry in a restricted taxonomic context (i.e. the tribe Lithospermeae of the Boragniaceae family) revealed that GABA concentration is particularly high in species with specialist bee- and bumblebee-pollination whilst β-alanine increases in species pollinated by flies and passerine birds. This result suggested to test the effect of an artificial diet consisting of 20% sucrose solutions enriched with GABA and β-alanine on some species of Apoidea. Results show that some species of insects increase their mobility, flying activity and survival time when fed with the artificial diet and particularly with the solution enriched with GABA. Although we used high concentration of the non-protein amino acid (20-fold higher than the concentration occurring in nectar), these results push us to further consider the role of GABA in increasing the mobility of insects between flowers and their foraging activity and thus their pollination performances.

Efforts to refine rations for captive rearing are dependent on a clear understanding of gut anatomy and function. Gross anatomic and histological descriptions of the gut of the Siberian sturgeon Acipenser baeri, are provided in this manuscript to serve as a baseline characterization for comparison during basic research and health surveys of Siberian sturgeon populations. Histological evaluations were carried out on 200 individuals (body weight ranging from 50 to 8000 g), using gross anatomy and light microscopy. The most characteristic finding is about pancreas, which has three distinct lobes. The pancreatic duct ends in a papilla between the small intestine and the pyloric caecum. Eosinophilic zymogen granules characterize exocrine cells, and the endocrine cells are grouped together in structures that are similar to mammalian Islets of Langerhans with not homogeneous distribution. Morphometrical evaluation shows that the mean area of the islets is 8.32 mm2×10-3. The Siberian sturgeon pancreas is a morphologically distinct organ functionally and histologically similar to that of mammals.

Olive mill vegetation water (VW) is an olive oil by-product rich in polyphenols has powerful antioxidant effects. In light of the interest on the research of novel natural antioxidants to use in fish feed, the aim of this research was to use VW as a potential substitute for artificial antioxidants in rainbow trout diet as well as checking its effects on the blood chemistry and digestive organ physiology of the fish. The experimental plan was monofactorial, balanced (4×3) and the experimental factor considered was the fish diet. Diets were isoproteic (CP 40%) and isoenergetic (18MJkg-1 DM) with two inclusion levels of VW (1 and 5%: VW1 and VW5) tested against a control diet. A feeding trial was performed on quadruplicate groups of 200 fish (mean body weight: 44.2g) fed experimental diets for 94days. At the end of the trial, the growth performance traits were determined and sampling of blood and different tissues (brain, ovary, stomach, liver, and intestine) were carried out for haematology, endocrinology, histology, and digestive enzyme analysis. The main results of the present experimentation are that VW inclusion in rainbow trout feed slightly affects the productive traits and blood chemistry, while the histological structure of digestive organs and digestive enzyme physiology were not affected.