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Differentiation of tracheary elements (TEs) is finalized by programmed cell death (PCD) and autolysis. This review integrates TE differentiation, PCD, and autolysis in a biological and evolutionary context.

The problem of packing with items with conflicting time-window dependence on profit considering departure time is studied in the context of consolidation of goods in transport, which is a practical problem in the logistics industry. The objective is to select the loading plan that is most profitable based on the volume and time windows of the items. The time windows of items in the same box must intersect, and the intersection of the items’ time windows affects the box’s departure time and hence the profit-dependent time. The problem is identified as an integer programming model for decision making, and two modeling strategies are proposed to address it by improving the GRASP heuristic. Multi-class examples are used in experiments to confirm that the improved algorithm can solve the problem efficiently, find the near-optimal solution in a shorter time, and enhance customer satisfaction.

Evolutionary, as well as genetic, evidence suggests that vascular development evolved originally as a cell death programme that allowed enhanced movement of water in the extinct protracheophytes, and that secondary wall formation in the water-conducting cells evolved afterwards, providing mechanical support for effective long-distance transport of water. The extant vascular plants possess a common regulatory network to coordinate the different phases of xylem maturation, including secondary wall formation, cell death, and finally autolysis of the cell contents, by the action of recently identified NAC domain transcription factors. Consequently, xylem cell death is an inseparable part of the xylem maturation programme, making it difficult to uncouple cell death mechanistically from secondary wall formation, and thus identify the key factors specifically involved in regulation of cell death. Current knowledge suggests that the necessary components for xylem cell death are produced early during xylem differentiation, and cell death is prevented through the action of inhibitors and storage of hydrolytic enzymes in inactive forms in compartments such as the vacuole. Bursting of the central vacuole triggers autolytic hydrolysis of the cell contents, which ultimately leads to cell death. This cascade of events varies between the different xylem cell types. The water-transporting tracheary elements rely on a rapid cell death programme, with hydrolysis of cell contents taking place for the most part, if not entirely, after vacuolar bursting, while the xylem fibres disintegrate cellular contents at a slower pace, well before cell death. This review includes a detailed description of cell morphology, function of plant growth regulators, such as ethylene and thermospermine, and the action of hydrolytic nucleases and proteases during cell death of the different xylem cell types.

Background Plant secondary cell wall is a renewable feedstock for biofuels and biomaterials production. Arabidopsis VASCULAR-RELATED NAC DOMAIN (VND) has been demonstrated to be a key transcription factor regulating secondary cell wall biosynthesis. However, less is known about its role in the woody species. Results Here we report the functional characterization of Populus deltoides WOOD-ASSOCIATED NAC DOMAIN protein 3 (PdWND3A), a sequence homolog of Arabidopsis VND4 and VND5 that are members of transcription factor networks regulating secondary cell wall biosynthesis. PdWND3A was expressed at higher level in the xylem than in other tissues. The stem tissues of transgenic P. deltoides overexpressing PdWND3A ( OXPdWND3A ) contained more vessel cells than that of wild-type plants. Furthermore, lignin content and lignin monomer syringyl and guaiacyl (S/G) ratio were higher in OXPdWND3A transgenic plants than in wild-type plants. Consistent with these observations, the expression of FERULATE 5-HYDROXYLASE1 (F5H1) , encoding an enzyme involved in the biosynthesis of sinapyl alcohol (S unit monolignol), was elevated in OXPdWND3A transgenic plants. Saccharification analysis indicated that the rate of sugar release was reduced in the transgenic plants. In addition, OXPdWND3A transgenic plants produced lower amounts of biomass than wild-type plants. Conclusions PdWND3A affects lignin biosynthesis and composition and negatively impacts sugar release and biomass production.

In this paper, an unrelated parallel machine scheduling problem with sequence and machine-dependent setup times and makespan minimization is studied. A new makespan linearization and several mixed integer formulations are proposed for this problem. These formulations outperform the previously published formulations regarding size of instances and computational time to reach optimal solutions. Using these models, it is possible to solve instances six times larger than what was previously solved and to obtain optimal solutions on instances of the same size up to four orders of magnitude faster. A metaheuristic algorithm based on multi-start algorithm and variable neighbourhood descent metaheuristic is proposed. Composite movements were defined for the improvement phase of the proposed metaheuristic algorithm that considerably improved the performance of the algorithm providing small deviations from optimal solutions in medium-sized instances and outperforming the best known solutions for large instances.

Wiring a complex brain requires many neurons with intricate cell specificity, generated by a limited number of neural stem cells. Drosophila central brain lineages are a predetermined series of neurons, born in a specific order. To understand how lineage identity translates to neuron morphology, we mapped 18 Drosophila central brain lineages. While we found large aggregate differences between lineages, we also discovered shared patterns of morphological diversification. Lineage identity plus Notch-mediated sister fate govern primary neuron trajectories, whereas temporal fate diversifies terminal elaborations. Further, morphological neuron types may arise repeatedly, interspersed with other types. Despite the complexity, related lineages produce similar neuron types in comparable temporal patterns. Different stem cells even yield two identical series of dopaminergic neuron types, but with unrelated sister neurons. Together, these phenomena suggest that straightforward rules drive incredible neuronal complexity, and that large changes in morphology can result from relatively simple fating mechanisms.

Key messageThe homologs of VASCULAR RELATED NAC-DOMAIN in the peat moss Sphagnum palustre were identified and these transcriptional activity as the VNS family was conserved.In angiosperms, xylem vessel element differentiation is governed by the master regulators VASCULAR RELATED NAC-DOMAIN6 (VND6) and VND7, encoding plant-specific NAC transcription factors. Although vessel elements have not been found in bryophytes, differentiation of the water-conducting hydroid cells in the moss Physcomitrella patens is regulated by VND homologs termed VND-NST-SOMBRERO (VNS) genes. VNS genes are conserved in the land plant lineage, but their functions have not been elucidated outside of angiosperms and P. patens. The peat moss Sphagnum palustre, of class Sphagnopsida in the phylum Bryophyta, does not have hydroids and instead uses hyaline cells with thickened, helical-patterned cell walls and pores to store water in the leaves. Here, we performed whole-transcriptome analysis and de novo assembly using next generation sequencing in S. palustre, obtaining sequences for 68,305 genes. Among them, we identified seven VNS-like genes, SpVNS1-A, SpVNS1-B, SpVNS2-A, SpVNS2-B, SpVNS3-A, SpVNS3-B, and SpVNS4-A. Transient expression of these VNS-like genes, with the exception of SpVNS2-A, in Nicotiana benthamiana leaf cells resulted in ectopic thickening of secondary walls. This result suggests that the transcriptional activity observed in other VNS family members is functionally conserved in the VNS homologs of S. palustre.

Variable machine efficiency (VME) and maintenance activities (MA) are critical factors often unexplored in job scheduling problems. This paper introduces a new problem termed the job-shop scheduling problem with variable machine efficiency and maintenance activities (JSSP-VME-MT), wherein, unlike the traditional JSSP, machine efficiency and maintenance activities are explicitly incorporated into the scheduling process. The study proposes a novel memetic algorithm (MA) underpinned by a variable neighborhood descent (VND) local search strategy to address this complex problem. This methodology demonstrates significant improvements, achieving mean makespan reductions ranging from 2.22% to 5.77% across diverse problem instances with varying numbers of machines and jobs. Key contributions include the development of an encoding scheme to model maintenance activities and machine-specific constraints, along with the design of a hybrid metaheuristic framework combining global exploration and local refinement. This work provides a foundation for future comparative studies, algorithm enhancements, and practical industrial applications. The approach offers a scalable and flexible solution to job-shop scheduling challenges involving dynamic efficiency and planned maintenance activities.

AbstractAll vital processes in plants are regulated by a complex network of transcription factors. The formation of the cell wall, one of the key structures of plant cells that determines plant development and function, is tightly controlled. In particular, the main target genes regulated by transcription factors encode enzymes involved in polysaccharide metabolism, specifically their biosynthesis and modification. The transcriptional network governing secondary cell wall formation comprises the bulk of vascular and mechanical tissues, which together constitute a general component of wood. Despite overlapping main components, secondary cell walls in fibers and vessels are controlled by distinct master regulators. Flax phloem fibers form a tertiary cell wall composed mainly of cellulose and a small portion of pectins, with an absence of xylan and lignin. Formation of the tertiary cell wall requires the deposition of even a thin layer of secondary cell wall. For the first time, a comprehensive revision of VNS genes, belonging to the NAC family of transcription factors, has been performed in flax. The NST group of NAC transcription factors, potentially involved in secondary cell wall formation in both phloem and xylem fibers, has been identified. These genes represent valuable targets for both fundamental studies on cell wall biogenesis and molecular-genetic manipulation aimed at improving plant quality.

Summary Constitutive expression of hypersensitive cell‐death‐inducing effectors secreted by pathogens has proved to be difficult in plants. Herein, xylem‐specific promoters (PVND7 or PVND2) were utilized to express three cell‐death‐inducing proteins (FocSIX1A, FocSIX6 or TvSm1) of fungal origin in banana plants. The regenerated plants were not only healthy but also showed improved resistance to fungal (Foc vcg0124 and Foc vcg0125) infection. These banana plants developed systemic resistance‐like symptoms, including elevated jasmonic acid content, callose depositions, increased xylem wall thickness and expression of several defence‐associated genes. Interestingly, expression of NAC105, a homologue of VND (vascular‐related NAC domain) transcription factor, was elevated in all these transgenic lines. Employing a novel positive‐feedback loop using VND genes, banana lines with thicker xylem walls devoid of any ectopic lignification were developed. Enhanced disease resistance of these lines against Foc strains, increased expression of defence genes, elevated jasmonic acid content and quantitative elevation of phenolic compounds provide evidence that elevation in xylem wall thickness does indeed contribute to systemic resistance by playing a crucial role in regulating immune responses. The current study demonstrates that (a) plants that express cell‐death‐inducing proteins in xylem can be regenerated, (b) these plants are healthy and show enhanced disease resistance and (c) a novel feedback loop involving vascular proteins, which specifically elevates xylem wall thickness without negatively affecting growth, exists in plants.