Fat storage in Drosophila suzukii is influenced by different dietary sugars in relation to their palatability

The peripheral sensitivity and palatability of different carbohydrates was evaluated and their nutritional value assessed in adult females of D. suzukii by means of an electrophysiological, behavioural and metabolic approach. The electrophysiological responses were recorded from the labellar “l” type sensilla stimulated with metabolizable mono- and disaccharides (glucose and maltose) and a non-metabolizable sugar (sucralose); the response rating and the palatability to the same sugars, evaluated by recording the proboscis extension reflex (PER), was maltose>glucose>sucralose. The nutritional value of carbohydrates was assessed by means of survival trials and fatty acids profile. Flies fed on a diet containing maltose had a longer lifespan than flies on monosaccharides, while flies fed on a diet containing sucralose had a shorter one. In addition, the ability to store fat seems to be influenced by the different sugars in the diet and is in relationship with their palatability. In fact, data showed a higher synthesis of palmitic and palmitoleic acids, most likely derived from de-novo lipogenesis with glucose as precursor, in flies fed with maltose and glucose than with non-metabolizable sucralose. In conclusion, these results suggest that the ability to select different sugars on the basis of their palatability may favour the storage of energy reserves such as fat by de-novo lipogenesis, determining a longer survival capability during prolonged periods of fasting

Fat storage in <i>Drosophila suzukii</i> is influenced by different dietary sugars in relation to their palatability - Fig 1

<p>(A) SEM image of a proboscis hemilabellum of <i>Drosophila suzukii</i> showing the distribution pattern of taste sensilla. (B) Corresponding schematic arrangement of the three sensillum types: small (s_1-9), intermediate (i_1-7) and large (l_1-9).</p

Survival results.

<p>Mean values ± s.e.m. of percentage of flies survived on each feeding substrate after 12, 24, 36 and 48 h fasting. Filled symbols indicate significantly different from control 1 (100% of insects at the end of feeding and start of starvation) (P<0.05; Duncan’s test). Different letters indicate significant differences between sugars at each time check (P<0.0001; Duncan’s test). (*) indicates significant differences from control 2 (starved flies) (P<0.01; Tukey test).</p

Fatty acids profile in experimental groups after feeding for 72h with different sugars and fasting for 36h in alive flies.

<p>Different letters indicate significant differences in nmoles/fly of fatty acids between day 0 and values for the various sugars (P<0.05; Tukey test).</p

Electrophysiological, PER and CAFE results.

<p>A) Mean values ± s.e.m. of spike frequency of “sugar” GRN following stimulation with 100 mM maltose, glucose and sucralose. N = 45–50. B) Mean values ± s.e.m. of PER activity following stimulation of labellar sensilla with 100 mM maltose, glucose and sucralose. N = 33. C) Mean values ± s.e.m. of the amount of maltose, glucose or sucralose intake under double-choice conditions. N = 5. * = P<0.05; ** = P<0.005.</p

Metabolic results.

<p>Mean values ± s.e.m. of percentage of total FA, SAFA, MUFA and PUFA in experimental groups after feeding for 72h with different sugars (A) and fasting for 36h in alive flies (B). Asterisk indicates significant differences from the control (100% = day 0). Different letters indicate significant differences between sugars (P < 0.05; Tukey test or P < 0.05: Duncan’s test subsequent to one-way ANOVA).</p

Characterization of sugar GRN in "l" type sensilla.

<p>Samples of spike discharges and dose-response relationship between spike activity of GRNs of an "l" type sensillum and 1÷100 mM maltose, glucose and sucralose. Mean values ± s.e.m. N = 32–34. Filled symbols indicate significant differences between a concentration and the next lower (P<0.001; Tukey test subsequent to repeated measures ANOVA). Different spike types are indicated by the following symbols: square = "L" spike; triangle = "M" spike; circle = "S" spike.</p

Clinical and pathological factors influencing survival in a large cohort of triple-negative breast cancer patients

Abstract Background To provide further information on the clinical and pathological prognostic factors in triple-negative breast cancer (TNBC), for which limited and inconsistent data are available. Methods Pathological characteristics and clinical records of 841 TNBCs diagnosed between 1994 and 2015 in four major oncologic centers from Sardinia, Italy, were reviewed. Multivariate hazard ratios (HRs) for mortality and recurrence according to various clinicopathological factors were estimated using Cox proportional hazards models. Results After a mean follow-up of 4.3 years, 275 (33.3%) TNBC patients had a progression of the disease and 170 (20.2%) died. After allowance for study center, age at diagnosis, and various clinicopathological factors, all components of the TNM staging system were identified as significant independent prognostic factors for TNBC mortality. The HRs were 3.13, 9.65, and 29.0, for stage II, III and IV, respectively, vs stage I. Necrosis and Ki-67 > 16% were also associated with increased mortality (HR: 1.61 and 1.99, respectively). Patients with tumor histotypes other than ductal invasive/lobular carcinomas had a more favorable prognosis (HR: 0.40 vs ductal invasive carcinoma). No significant associations with mortality were found for histologic grade, tumor infiltrating lymphocytes, and lymphovascular invasion. Among lymph node positive TNBCs, lymph node ratio appeared to be a stronger predictor of mortality than pathological lymph nodes stage (HR: 0.80 for pN3 vs pN1, and 3.05 for >0.65 vs <0.21 lymph node ratio), respectively. Consistent results were observed for cancer recurrence, except for Ki-67 and necrosis that were not found to be significant predictors for recurrence. Conclusions This uniquely large study of TNBC patients provides further evidence that, besides tumor stage at diagnosis, lymph node ratio among lymph node positive tumors is an additional relevant predictor of survival and tumor recurrence, while Ki-67 seems to be predictive of mortality, but not of recurrence