Postmating isolation and genetically variable host use in ecologically divergent host forms of Neochlamisus bebbianae leaf beetles.

Ecological speciation studies have more thoroughly addressed premating than postmating reproductive isolation. This study examines multiple postmating barriers between host forms of Neochlamisus bebbianae leaf beetles that specialize on Acer and Salix trees. We demonstrate cryptic isolation and reduced hybrid fitness via controlled matings of these host forms. These findings reveal host-associated postmating isolation, although a nonecological, 'intrinsic' basis for these patterns cannot be ruled out. Host preference and performance results among cross types further suggest sex-linked maternal effects on these traits, whereas family effects indicate their genetic basis and associated variation. Genes of major effect appear to influence these traits. Together with previous findings of premating isolation and adaptive differentiation in sympatry, our results meet many assumptions of 'speciation with gene flow' models. Here, such gene flow is likely asymmetric, with consequences for the dynamics of future ecological divergence and potential ecological speciation of these host forms.

Symbiont-mediated phenotypic variation without co-evolution in an insect-fungus association.

Recent studies have shown that symbionts can be a source of adaptive phenotypic variation for their hosts. It is assumed that co-evolution between hosts and symbionts underlies these ecologically significant phenotypic traits. We tested this assumption in the ectosymbiotic fungal associate of the gall midge Asteromyia carbonifera. Phylogenetic analysis placed the fungal symbiont within a monophyletic clade formed by Botryosphaeria dothidea, a typically free-living (i.e. not associated with an insect host) plant pathogen. Symbiont isolates from four divergent midge lineages demonstrated none of the patterns common to heritable microbial symbioses, including parallel diversification with their hosts, substitution rate acceleration, or A+T nucleotide bias. Amplified fragment length polymorphism genotyping of the symbiont revealed that within-lineage genetic diversity was not clustered along host population lines. Culture-based experiments demonstrated that the symbiont-mediated variation in gall phenotype is not borne out in the absence of the midge. This study shows that symbionts can be important players in phenotypic variation for their hosts, even in the absence of a co-evolutionary association.

Carcinoid tumours.

Carcinoid tumours offer a diagnostic and therapeutic challenge. Although new biochemical markers and improved methods for tumour detection, including PET and somatostatin receptor scintigraphy, have been developed during the last two decades many patients are still diagnosed at late stages of the disease. This is supported by the fact that the age of diagnosis is about the same today as it was 10 years ago. It is our opinion that plasma chromogranin A levels should be be determined in all patients which are investigated because of symptoms that might be connected to a neuroendocrine tumour. In cases with flushing or diarrhoea, U-5-HIAA should also be determined and these two tumour markers are enough to diagnose most patients with midgut carcinoid tumours. In patients with foregut or hindgut tumours other specific hormones should be included. For the localization procedure conventional radiological techniques including CT, MRI and ultrasound investigations should be supplemented with somatostatin receptor scintigraphy. Endoscopic ultrasound investigations might in the future be relevant for diagnosis of duodenal carcinoids, whereas gastric and rectal carcinoids are diagnosed by endoscopy. A combination of more aggressive surgery combined with medical treatment such as somatostatin analogues and alpha-interferon has significantly increased the survival rates in patients with classical midgut carcinoid tumours. Metastatic foregut and hindgut tumours are still a therapeutic challenge and it is important in the future to classify all carcinoid tumours based on specific tumour biology patterns. Such a tumour biology based treatment is a prerequisite for a more individually based therapy in the future.

Octreotide and interferon alfa: a new combination for the treatment of malignant carcinoid tumours.

24 patients with malignant carcinoid tumours received octreotide and interferon alfa (IFN-alpha). All the patients initially received octreotide 50-100 micrograms, twice daily. When progressive symptoms or increasing biochemical markers were observed, the daily dose was raised to a median 300 micrograms. If the initial dose proved ineffective or if no improvement was seen after escalation, IFN-alpha was added (median 9 MU subcutaneously per week). After the addition of IFN-alpha, 17 of the 22 patients (77%) with elevated urinary 5-hydroxyindoleacetic acid showed a significant (> 50%) reduction. Only 1 patient progressed and 4 had continuously stable biochemical disease. No significant reduction in tumour size was noted; in 5 patients, the tumour continued to grow despite decreasing hormone levels. 18 patients had carcinoid syndrome when IFN-alpha was added in 10 (56%) symptoms ameliorated. Thus, the addition of IFN-alpha is beneficial for patients with malignant carcinoid tumours that progress and/or who do not respond to octreotide.