scDNA-DNA hybridization studies in Pacific and Caribbean isolates ofDictyosphaeria cavernosa (Chlorophyta) indicate a long divergence

Genomic size and complexity were calculated for the pantropical chlorophyte,Dictyosphaeria cavernosa (Cladophorales). Genome characterization of the Hawaiian material by means of DNA renaturation studies showed highly repetitive (31.3%), middle repetitive (42.7%), and single-copy (25.8%) fractions; and an estimated haploid genome size of 1.79 pg DNA. A G:C content of 43% was calculated from a melting curve of DNA. Pacific and Caribbean isolates of this species were compared using single-copy nuclear DNA-DNA hybridization. Results show a relatively low thermal stability of the hybridized DNA (Δ Tm(e)=10°C) which suggests that these Pacific and Caribbean lineages may have been separated for up to 55 Ma.     

Nutrient limitation and nutrient‐driven shifts in plant species composition in a species‐rich fen meadow

Question: We studied the development and persistence of the effects of nutrient pulses on biomass production and species composition in a fen meadow. Location: Nature reserve, central Netherlands, 5 m a.s.l. Methods: Single pulse fertilization with N and P in a factorial design on an undrained central and a drained margin site in a species‐rich fen meadow (Cirsio dissecti‐Molinietum). Biomass production and species composition were monitored during four years. Results: At the central site, N addition boosted biomass production, but only during one year. The species composition was not changed. P fertilization increased the biomass production and changed the species composition from a vegetation dominated by Carex panicea to a grassland community with abundant Holcus lanatus, but not before the second year. At the margin site, P fertilization changed the species composition in a similar way, but biomass production was not increased. N fertilization had no effect. At both sites the P induced shift in species composition persisted for four years although the P effect declined during the experiment. Conclusions: The biomass responses show that N was limiting in the central site. Another nutrient, besides N and P (probably K) must have been limiting in the marginal site. The fast decline of the N effect on biomass is ascribed to increased denitrification and biomass removal. The delay in the P effect on biomass and species composition and the persistence of the P effect on species composition are ascribed to fast immobilisation and subsequent slow release of fertilizer P in the peat soil. Recurrence of the P pulses is expected to cause permanent changes in species composition.     

When and how did the Mikrotia fauna reach Gargano (Apulia,Italy)?

The time and mode of colonization of Gargano have been a subject of debate. Taking into account the temporal distribution of the ancestors of the Mikrotia fauna, a Late Tortonian age represents the best fit for the time of migration. How these animals reached the island is even harder to decide. In the past some scholars embraced rafting as an important mechanism enabling small mammals to reach the islands, whereas others rejected this hypothesis, considering it an improbable mode of colonization. The recent record of oceanic rafts indicates that rafting is indeed a very plausible method for small-sized animals to reach islands, and the most probable method for the colonization of Gargano. A polyphasic model, as proposed by Masini and colleagues, is rejected in the case of Gargano, as it is based on a misinterpretation of the adaptive radiations within the Mikrotia fauna.     

Nutations in Shoots and in Desmodium Lateral Leaflets, Nyctinastism and Seismonastism in Mimosa pudica. Comparison and Evolution of Morphology and Mechanism

Four plant movements are considered: circumnutation of apeces of Phaseolus, nutations (ultradian movement) of lateral leaflets of Desmodium gyrans, nyctinastim and Mimosa pudica seismonastic movement. The rhythms mechanisms are briefly summarized except for seismonastism: in this case, experimental evidence progressively accumulated, at first indirect and recently direct is described, leading eventually to conclusions about the existence and function of contractile proteins. Indeed, in spite of the nowadays clear evidence, the mechanism has not yet gained total recognition among plant physiologists and it is usually overseen or ignored in a reductionist approach. From these four exemplative cases, an interesting evolutionary organization change is apparent in movement, morphogenesis, chemistry and mechanism.     

Store-operated Ca channels in prostate cancer epithelial cells: function, regulation, and role in carcinogenesis

Ca²⁺ homeostasis mechanisms, in which the Ca²⁺ entry pathways play a key role, are critically involved in both normal function and cancerous transformation of prostate epithelial cells. Here, using the lymph node carcinoma of the prostate (LNCaP) cell line as a major experimental model, we characterize prostate-specific store-operated Ca²⁺ channels (SOCs)—a primary Ca²⁺ entry pathway for non-excitable cells—for the first time. We show that prostate-specific SOCs share major store-dependent, kinetic, permeation, inwardly rectifying, and pharmacological (including dual, potentiation/inhibition concentration-dependent sensitivity to 2-APB) properties with “classical” Ca²⁺ release-activated Ca²⁺ channels (CRAC), but have a higher single channel conductance (3.2 and 12 pS in Ca²⁺- and Na⁺-permeable modes, respectively). They are subject to feedback inhibition via Ca²⁺-dependent PKC, CaMK-II and CaM regulatory pathways and are functionally dependent on caveolae integrity. Caveolae also provide a scaffold for spatial co-localization of SOCs with volume-regulated anion channels (VRAC) and their Ca²⁺-mediated interaction. The TRPC1 and TRPV6 members of the transient receptor potential (TRP) channel family are the most likely molecular candidates for the formation of prostate-specific endogenous SOCs. Differentiation of LNCaP cells to an androgen-insensitive, apoptotic-resistant neuroendocrine phenotype downregulates SOC current. We conclude that prostate-specific SOCs are important determinants in the transition to androgen-independent prostate cancer.