Confronting collinearity: comparing methods for disentangling the effects of habitat loss and fragmentation

Estimating the relative importance of habitat loss and fragmentation is necessary to estimate the potential benefits of specific management actions and to ensure that limited conservation resources are used efficiently. However, estimating relative effects is complicated because the two processes are highly correlated. Previous studies have used a wide variety of statistical methods to separate their effects and we speculated that the published results may have been influenced by the methods used. We used simulations to determine whether, under identical conditions, the following 7 methods generate different estimates of relative importance for realistically correlated landscape predictors: residual regression, model or variable selection, averaged coefficients from all supported models, summed Akaike weights, classical variance partitioning, hierarchical variance partitioning, and a multiple regression model with no adjustments for collinearity. We found that different methods generated different rankings of the predictors and that some metrics were strongly biased. Residual regression and variance partitioning were highly biased by correlations among predictors and the bias depended on the direction of a predictor’s effect (positive vs. negative). Our results suggest that many efforts to deal with the correlation between amount and fragmentation may have done more harm than good. If confounding effects are controlled and adequate thought is given to the ecological mechanisms behind modeled predictors, then standardized partial regression coefficients are unbiased estimates of the relative importance of amount and fragmentation, even when predictors are highly correlated.     

Production of Lectins from Marine Algae: Current Status,Challenges, and Opportunities for Non-Destructive Extraction

Marine algae are an excellent source of novel lectins. The isolation of lectins from marine algae expands the diversity in structure and carbohydrate specificities of lectins isolated from other sources. Marine algal lectins have been reported to have antiviral, antitumor, and antibacterial activity. Lectins are typically isolated from marine algae by grinding the algal tissue with liquid nitrogen and extracting with buffer and alcohol. While this method produces higher yields, it may not be sustainable for large-scale production, because a large amount of biomass is required to produce a minute amount of compound, and a significant amount of waste is generated during the extraction process. Therefore, non-destructive extraction using algal culture water could be used to ensure a continuous supply of lectins without exclusively disrupting the marine algae. This review discusses the traditional and recent advancements in algal lectin extraction methods over the last decade, as well as the steps required for large-scale production. The challenges and prospects of various extraction methods (destructive and non-destructive) are also discussed.     

Growth and Biochmical Studies of Mrigal Fish (Cirrhinus mrigala) Fed Graded Levels of Oil

A 45-day experiment was carried out to evaluate the growth performance,digestive enzymes activity and biochemical response of Cirrhinus mrigala fed graded levels of oil.Three isonitrogenous purified diets(6%,8%and 10%of oil)were formulated.A total of 108 juveniles of Cirrhinus mrigala(5.95±0.25)g were equally distributed in triplicate groups in nine plastic tanks of 100 L capacity and fed under natural light cycle.Growth performance of the fish significantly reflected the effect of inclusion levels of oil tested but the diet with 8%lipid had the best significant growth performance[%weight gain,Feed Conversion Ratio(FCR)and Specific Growth Rate(SGR)],across different experimental groups.Levels of secretion of digestive enzymes in the fish fed different experimental diets resulted in significant values of(p0.05)amylase and lipase,while Aspartate transaminase(AST),Alanine transaminase(ALT),Lactate dehydrogenase(LDH)and Malate dehydrogenase(MDH)values in the muscle and liver decreased significantly(p0.05)as the levels of oil in the diet increased.However,serum biochemical parameters did not record any significant difference(p0.05)with the exception of the total lipid across diets.The study confirmed the inclusion effect of graded levels of oil in juvenile Mrigal diet,but the inclusion should not be more than 8%to avert growth depression.     

Classification of Dutch and German avian reoviruses by sequencing the sigma C protein

We have amplified, cloned and sequenced (part of) the open reading frame of the S1 segment encoding the sigma C protein of avian reoviruses isolated from chickens with different disease conditions in Germany and The Netherlands during 1980 up to 2000. These avian reoviruses were analysed phylogenetically and compared with sequences of avian reoviruses in the Genbank database. The avian reoviruses could be grouped in 5 different genotyping clusters and this classification was identical when the sequences were compared of the 5' end, the 3' end or the whole open reading frame of the sigma C protein. Therefore sequencing of either part of the gene encoding the sigma C protein seems to be reliable for classification. We were unable to identify a correlation between sigma C sequences of the avian reoviruses and the disease condition they were isolated from. The sequences found in The Netherlands and in Germany are, like those in Taiwan, more dispersed than the known avian reovirus sigma C sequences in the USA and Australia. We did not establish temporal or geographic differences in the avian reoviruses studied.     

Mineralized paraprostatic cyst as a potential contributing factor in the development of perineal hernias in a dog

Perineal hernias almost exclusively affect male dogs (sexually intact or castrated). Factors that may contribute or predispose a dog to perineal hernias include tenesmus, pelvic musculature variations (male vs female), and gonadal hormone influence. In dogs with perineal hernias and tenesmus it is important to include rectal and prostatic diseases, including paraprostatic cysts, in the differential list of potential underlying causes. Surgical correction of the perineal hernia with a perineal herniorrhaphy is indicated. Successful treatment depends on the degree of preexisting neurologic alterations, meticulous surgical technique, and identification and correction of underlying contributing factors. Paraprostatic cysts develop predominantly in sexually intact medium to large breed dogs. These cysts are thin-walled structures often attached to the prostatic dorsal midline. Osseous metaplasia of paraprostatic cysts may occur. Clinical signs of tenesmus often result from compression on adjacent structures (urinary bladder and colon), and tenesmus may contribute to the development of perineal hernias. Preferred treatment of a paraprostatic cyst is surgical removal and castration. This report describes a dog with bilateral perineal hernias and a large mineralized paraprostatic cyst that was identified as a possible contributing factor to the hernias.