Antimicrobial Compounds from Eukaryotic Microalgae against Human Pathogens and Diseases in Aquaculture

The search for novel compounds of marine origin has increased in the last decades for their application in various areas such as pharmaceutical, human or animal nutrition, cosmetics or bioenergy. In this context of blue technology development, microalgae are of particular interest due to their immense biodiversity and their relatively simple growth needs. In this review, we discuss about the promising use of microalgae and microalgal compounds as sources of natural antibiotics against human pathogens but also about their potential to limit microbial infections in aquaculture. An alternative to conventional antibiotics is needed as the microbial resistance to these drugs is increasing in humans and animals. Furthermore, using natural antibiotics for livestock could meet the consumer demand to avoid chemicals in food, would support a sustainable aquaculture and present the advantage of being environmentally friendly. Using natural and renewable microalgal compounds is still in its early days, but considering the important research development and rapid improvement in culture, extraction and purification processes, the valorization of microalgae will surely extend in the future.     

Extraction and HPLC analysis of phenolic compounds in leaves, stalks, and textile fibers of Urtica dioica L

In the present study the phenolic composition of leaves, stalks, and textile fiber extracts from Urtica dioica L. is described. Taking into account the increasing demand for textile products made from natural fibers and the necessity to create sustainable "local" processing chains, an Italian project was funded to evaluate the cultivation of nettle fibers in the region of Tuscany. The leaves of two nettle samples, cultivated and wild (C and W), contain large amounts of chlorogenic and 2- O-caffeoylmalic acid, which represent 71.5 and 76.5% of total phenolics, respectively. Flavonoids are the main class in the stalks: 54.4% of total phenolics in C and 31.2% in W samples. Anthocyanins are second in quantitative importance and are present only in nettle stalks: 28.6% of total phenolics in C and 24.4% in W extracts. Characterization of phenolic compounds in nettle extracts is an important result with regard to the biological properties (antioxidant and antiradical) of these metabolites for their possible applications in various industrial activities, such as food/feed, cosmetics, phytomedicine, and textiles.     

DNA- and RNA-derived assessments of fungal community composition in soil amended with sewage sludge rich in cadmium, copper and zinc

Current UK legislation permits the application of sewage sludge to agricultural land provided concentrations of heavy metals in soil do not increase above maximum permissible limits. However, even within the defined limits, we do not know how an increase in soil heavy metal concentrations is likely to affect biological diversity and activity. Here we report on the effects of sewage sludge addition, including sludge rich in the metals cadmium, copper and zinc, on soil fungal community composition using both an rDNA and rRNA DGGE approach. Sewage sludge addition altered fungal ITS-DGGE banding patterns, however, there were no additional effects of an increase in soil heavy metal concentrations. Similar results were obtained for the full range of copper rich sludge treatments even when copper concentrations were well above the maximum permissible limits. Our data therefore demonstrate that although an increase in soil organic matter content alters soil fungal community diversity and composition, increasing soil concentrations of cadmium, copper and zinc up to current legislative limits had little additional effect regardless of whether rRNA or rDNA was analysed. This suggests that current UK limits for these three heavy metals are within a concentration range that the dominant soil fungi at this field site can tolerate.     

Effects of thyroxine administration on the growth and survival of pike silverside (Chirostoma estor) juveniles

The pike silverside has high aquaculture potential despite its slow growth. In this study, thyroxine (T₄) concentrations (0.13, 1.3 and 13 nM), a control with no hormonal supplement and a negative control containing 4.5 mM methimazole (MMI) were tested to evaluate the growth of this species. Juveniles (0.2 g) were exposed by immersion to these treatments for 8 h every second day for 120 days, and growth evaluations were performed monthly over the entire trial period. In addition, tissue samples from each treatment group were assayed for triiodothyronine (T₃) and deiodinase type 2 (D2) activity . The survival rates in all T₄ groups were high, and a significant increase in growth was observed (average of 58%). The MMI treatment caused an increase in mortality and a reduction in the final body weight compared with the control. T₄ administration did not affect the tissue levels of T₃, and it decreased muscular D2 activity only after 30 days of exposure. These results demonstrated that low concentrations of T₄ in the culture environment could improve the growth of this species without affecting tissue hormone levels. The technique may have useful applications for early‐stage aquaculture of this and other economically important species.     

Reactions of sera from laboratory, domestic and wild animals in Africa with Protein a and a recombinant chimeric Protein AG

An ELISA was developed to determine the reactivity of peroxidase labelled Protein A and a recombinant Protein A + Protein G construct, to sera from a variety of laboratory, domestic and wild animals from Africa. There was variability in the binding capacity of sera from individuals of the same species, but four groups could be recognized. Sera from birds and crocodiles were at most weakly reactive with either Protein A or the chimeric construct. Sera from some domestic animals such as horse, goat and cat, and sera from some wild ungulates including buffalo, wildebeest, waterbuck and impala were reactive with Protein A, but reacted to a much greater degree with the chimeric construct. Sera from larger wild animals such as elephant, rhinoceros and giraffe were strongly reactive with the chimeric protein and moderately reactive with Protein A. Sera from primates and dog, pig, guinea pig and rabbit reacted strongly with both proteins. Chimeric proteins that combine the IgG binding capacities of Protein A and Protein G can be used to detect immunoglobulin from a wide variety of African wild animal species. They may thus be of great value in seroepidemiological investigations of these animal populations.     

Multiple rib fracture in a neonatal foal using a nylon strand suture repair technique

OBJECTIVES: To report rib fracture repair using the Securos Cranial Cruciate Ligament Repair System (SCCLRS; Securos Veterinary Orthopedics, Charlton, MA) in a neonatal foal. STUDY DESIGN: Case report. ANIMALS: A 1-day-old Standardbred foal with fracture of left ribs 2-9. METHODS: Four days after admission the foal was anesthetized and rib fractures were repaired using open reduction and the SCCLRS. RESULTS: Rib fractures were successfully stabilized and the foal was discharged 7 days postoperatively without further complications. CONCLUSIONS: The SCCLRS provided a straightforward, effective method of rib fracture repair in neonatal foals. CLINICAL RELEVANCE: Effective rib fracture repair in neonatal foals can be achieved with the SCCLRS.     

Hemangiosarcoma in 11 young horses

Hemangiosarcoma is a rare neoplasm of horses and hemangiosarcoma in young horses might behave differently than in mature horses. The purpose of this study was to identify the characteristics of hemangiosarcoma occurring in horses < or = 3 years of age. Medical records from 1982 to 2004 were searched for horses < or = 3 years of age with a histopathologic diagnosis of hemangiosarcoma. Eleven records were identified. Thoroughbred and Thoroughbred crosses predominated. Age ranged from 9 days to 3 years. All horses presented with cutaneous or leg swellings or joint effusion. Physical examination findings included tachycardia, fever, and depression. Laboratory abnormalities included anemia (5/11), hyperfibrinogenemia (4/11), hypofibrinogenemia (3/11), thrombocytopenia (2/11), and neutrophilic leukocytosis (1/11). Ultrasonographic and radiographic evaluation was not diagnostic in any case. Antemortem histopathologic diagnosis was obtained in 10 cases. Six of 11 horses were euthanized. Surgical resection was performed in 5 horses, 2 of which were later euthanized. Diagnosis was confirmed histologically at postmortem examination in all euthanized horses. Two cases resolved spontaneously. Early histopathologic diagnosis may allow cure if the mass is localized and amenable to surgical resection. In cases where the horse is medically stable, and masses are not interfering with quality of life, a period of observation may be warranted.     

Relationship between antimicrobial susceptibility of clinical mastitis pathogens and treatment outcome in cows

OBJECTIVE: To determine whether there was any association between results of in vitro antimicrobial susceptibility testing of pathogens isolated from cows with mild or moderate clinical mastitis and outcome of treatment. DESIGN: Observational study. ANIMALS: 133 cows with mild or moderate mastitis in a single quarter. PROCEDURE: Cows were treated by means of intramammary infusion of pirlimycin (50 mg) in the affected quarter once daily for 2 days; additional intramammary treatments with the same product were administered if the milk continued to appear abnormal. Duration of treatment and days until clinical cure were recorded. Bacterial isolates were tested for antimicrobial susceptibility by means of a broth micro-dilution technique. RESULTS: Environmental streptococci, coliforms, and coagulase-negative Staphylococcus spp were the most commonly isolated pathogens. Duration of treatment and days until clinical cure were not significantly different for cows from which pathogens that were susceptible or resistant to pirlimycin were isolated. Bacteriologic cure rates 14 and 21 days after treatment were not significantly different for cows with mastitis caused by susceptible or resistant bacteria. Similar results were found when data only from cows with mastitis caused by gram-positive isolates were analyzed. CONCLUSIONS AND CLINICAL RELEVANCE: In the present study, differences in clinical outcome for cows with mild or moderate mastitis that could be attributed to differences in results of in vitro susceptibility testing were not identified. The use of in vitro susceptibility testing to guide intramammary mastitis treatment cannot be recommended on the basis of results of this study.